WO2000073529A1 - Aluminum alloy hollow material, aluminum alloy extruded pipe material for air conditioning piping and method of manufacturing it - Google Patents

Abstract

An aluminum alloy hollow material manufactured by port-hole-extruding or port-hole-extruding and extraction-drawing an aluminum alloy ingot containing at least 0.3 to 1.5 wt.% of Mn, wherein differences in electric conductivity between sections in a lengthwise direction of the hollow material are less then 1.0 IACS % and a preferential corrosion at deposited portions during port-hole-extrusion can be prevented; and a method of manufacturing the hollow material.

Description

 Description Aluminum alloy hollow material, aluminum alloy extruded tube material for air conditioner piping, and method for producing the same

 The present invention relates to a high corrosion resistant Mn-containing aluminum alloy hollow material useful as a building material and the like, which is manufactured by using a porthole extrusion method, and a method for manufacturing the same.

 Furthermore, the present invention relates to an aluminum alloy extruded pipe for air conditioner piping suitable for a metal pipe portion such as a refrigerant pipe of an automobile cooler, and a low-cost manufacturing method of the extruded pipe. Background art

 BACKGROUND ART Aluminum alloy hollow materials such as hollow hollow materials having a square cross section used for building materials and tubes having a circular cross section for refrigerants have been conventionally manufactured by a porthole extrusion method.

 Port hole extrusion methods include JIS 100 series (pure A 1 series), 3 000 series (A 1-M n series), 600 000 series (A l-M g-Si series), It is used for the production of relatively soft aluminum alloy hollow materials such as 700-based (Al-Zn-Mg-based) that do not contain copper.

In the above port hole extrusion, an extrusion billet is formed from a predetermined aluminum alloy into a gunshot mass by a normal DC manufacturing method (semi-continuous vertical manufacturing method) or a hot-top manufacturing method. Then, the lumps are subjected to a homogenization treatment to reduce segregation, and the lumps are cut into a predetermined length to produce the lumps. Thereafter, the extruded billet is reheated by a low-frequency induction furnace (induction heater) or a gas heating furnace and hot extruded into a hollow material. The reheating temperature is determined in the range of 370 to 530 ° C in consideration of the extrudability and the quality of the extruded material, and is often determined in the temperature range of 400 to 500 ° C.

 The above-mentioned porthole extruded hollow material may be subjected to drawing processing in order to reduce dimensional accuracy and diameter. There are two methods of drawing: a method of pulling out a short extruded hollow material with a drawing bench, and a method of drawing out a long extruded hollow material with a continuous drawing machine using a floating plug. The hollow material after the drawing process is subjected to a solution treatment, an aging treatment, an annealing treatment, etc., depending on the intended use, to thereby impart strength and workability.

 On the other hand, aluminum alloy tubes have been used for heat exchanger piping in automobiles for the purpose of weight reduction.

 For example, refrigeration piping for automobile coolers is made of JIS6063 alloy (representative composition A1-0.5 wt% M), which has corrosion resistance to the external environment and strength enough to withstand refrigerant pressure and vibration of engines and compressors. g-

0.35 vt% S i) _Ν or JIS ₃₀₃ alloy (representative composition Al — 1.

0 vt% M n-0.1 wt% Cu-0.1 wt% Si (0.4 wt% Fe) is widely used.

 The JIS 603 alloy is used for piping, particularly so-called flex hose, which is required to withstand vibration fatigue resistance.The JIS 603 alloy is widely used for metal piping such as automobile coolers. Have been.

 The pipe made of the JIS 003 alloy is a circular pipe having an outer diameter of about 6 to 19 mm and a wall thickness of about 0.8 to 1.2 mm, and is manufactured by, for example, the following process.

First, the JIS 3003 alloy was rounded by a DC semi-continuous vertical manufacturing method. Gun into chunks. Next, in order to eliminate segregation of alloy components and impurities, the round bar 銪 is heated at a high temperature and homogenized. After cutting to a predetermined length, the extruded billet is reheated, and the extruded tube is extruded by mandrel extrusion. The extruded pipe is drawn into a pipe having a desired shape by drawing and then annealed to remove processing strain and impart appropriate workability.

 In the conventional manufacturing method, in order to ensure productivity, large billets with an outer diameter of 14 inches or more are extruded into a large-diameter, thick-walled extruded tube by mandrel extrusion, and the continuous drawing machine is used. Therefore, a method of performing multi-pass drawing is adopted.

 By the way, since the homogenization treatment of the lump affects the quality of the final product, the conditions are economical factors such as alloy components, ease of extrusion, required characteristics of the product, energy cost required for homogenization treatment, and time. Determined in consideration of factors.

 The homogenization conditions (holding temperature and holding time) for practical aluminum alloys subjected to hot extrusion are generally as follows.

 J I S 1 0 5 0 alloy: 52 0 ~ 5 6 0 ° (, 410 hr

J I S 11 0 0 Alloy: 5 2 0 5 6 0 ° C, 4 10 h r

J I S 3 0 3 Alloy: 57 0 6 10 ° C, 4 10 h r

JIS 304 alloy: 530 580 ° C, 410 hr JJ II SS 66 00 66 33 alloy gold: 520580. C, 410 hr

J I S 7 N 0 1 Alloy 450 0 490. C, 410 hr Here, cooling from the holding temperature to room temperature is performed by air cooling with a fan, cooling down, water sprinkling using a sprinkler, or the like.

The pipe manufactured in this manner is further subjected to end processing and bending processing, and is used as an automotive cooler pipe or the like. Various types of beads (joint parts) are formed by a combination of pipe expansion, contraction, and rolling, etc., in the end processing of the piping material. However, higher reliability is required for beads. A new method called shaft seal bead has been widely adopted. Due to the complicated shape of this shaft seal bead, higher workability is required for the tube material.

 In addition, automotive air conditioner piping must have good brazing properties and maintain high quality even when subjected to brazing heat.

In addition, aluminum tubing for cooler piping is required to have sufficient strength to withstand vibration and plastic workability, and an appropriate balance between strength and ductility is desired. For example, mandrel extruded JIS 3 0 0 3 alloy - drawing -. Mechanical properties of the pipes produced in the annealing step, the tensile strength of 9 5 ~ 1 2 5 N / mm 2, 0 2%耐Ka 3 5 N / mm ² or more and elongation 30% or more.

 In addition, corrosion resistance and formability are required for the outer surface of automotive piping. As for formability, dimensional accuracy of fine crystal grains, outer diameter, wall thickness, etc., and brazing properties, etc. are required so that roughening does not occur during processing.

 In order to reduce costs, the method of manufacturing aluminum alloy pipes for automotive pipes has been changed from mandrel extrusion to porthole continuous extrusion, and porthole extruded pipes are used directly as heat exchanger pipes and drawn. A method for simplifying the process, which omits the annealing step, is being studied.

 By the way, the port hole extrusion method is an extrusion method in which an extruded material is divided into a plurality of port holes and these are welded and integrated at an outlet of the port hole. A weld is formed.

That is, in the case of four-port extrusion, the aluminum alloy is once divided into four parts, which are welded together in the welding chamber of the extrusion die, and pass through the clearance between the die bearing part and the mandrel. Pressing the desired shape There are a plurality of welds that are continuous in the longitudinal direction to become a material, which remains after drawing.

 However, there is a problem that when the JIS 003 alloy tubing manufactured by the porthole extrusion method is exposed to a corrosive environment, the welded portion is significantly corroded (hereinafter referred to as preferential corrosion of the welded portion).

 For example, as shown in Fig. 1, the preferential corrosion of tubing obtained by the porthole extrusion method with four portholes is not only caused by pitting corrosion on the non-welded part, but also by the longitudinal Directionally continuous corrosion occurs preferentially.

 This preferential corrosion of the welded portion has a very high corrosion rate, and a through hole is formed in a short period of time. For example, when a 1 mm thick automotive air conditioner pipe is subjected to the CASS test, the pitting corrosion at the non-welded part does not penetrate after elapse of 400 hr, whereas the pitting corrosion at the welded part is less than 20 Ohr. Penetrate.

 This preferential corrosion tends to corrode more on the front end (first half) of the extrusion than on the rear end (second half). Therefore, securing the corrosion resistance of the welded portion over the entire length of the extruded material in the longitudinal direction has been an important technical issue.

 This preferential corrosion of the welded portion is likely to occur in the A1-Mn alloy, and occurs when the Mn content is 0.3 wt% or more, and rapidly progresses when the Mn content exceeds 0.8 wt%. Since Mn increases deformation resistance and lowers extrudability, the upper limit of the Mn content in porthole extrusion is about 1.5 wt%.

A1—Mn-based alloys have excellent strength and corrosion resistance, so JIS 300 (Mn content 1.0 to 1.5 wt%), JIS 3203 (Mn content 1.0 to 1.5 wt%) Alloys such as JIS 7 N 01 (Mn content 0.2 to 0.7 wt) are widely used. However, porthole extruded hollow materials have the problem of preferential corrosion described above, so their use has often been refrained from applications where corrosion resistance is important. In addition, various defects such as poor hue and gloss appearance occur between the welded portion and the non-welded portion.

 In addition, there are many longitudinal microscopic streaks (clearly identified as grooves in enlarged observation) formed by drawing in conventional aluminum alloy tubing for automotive air conditioner piping. Since this streak defect impairs the sealing performance and causes damage to the sealing ring rubber, a drastic solution to the defect is desired.

 An object of the present invention is to provide an A1-Mn-based alloy hollow material manufactured using a porthole extrusion method and having improved preferential corrosion of a welded portion. Another object of the present invention is to provide a method for producing the A1-Mn-based alloy hollow material.

 Another object of the present invention is to provide an aluminum alloy extruded tube for air-con piping having improved corrosion resistance and surface fine streaks. Another object of the present invention is to provide a method for producing the aluminum alloy extruded tube for air conditioner piping at a low cost.

 The above and other objects, features and advantages of the present invention will become more apparent from the following description. BRIEF DESCRIPTION OF THE FIGURES

 Fig. 1 is an explanatory diagram of preferential corrosion of the welded part of a pipe manufactured by the porthole extrusion method.

 FIGS. 2 (A), 2 (B), 2 (C) and 2 (D) are illustrations of end processing types A, B, C and D of extruded tubing for air conditioner piping.

FIG. 3 (A) shows the type B shown in FIG. 2 (B), and FIG. 3 (B) shows the type B shown in FIG. FIG. 4 (c) is an explanatory view of a process of processing each end of type C shown in FIG.

 Fig. 4 (A) is an SEM photograph of a current pipe, and Fig. 4 (B) is an SEM photograph of a type B end portion of each of the pipes of the present invention. Disclosure of the invention

 The present inventors have investigated the preferential corrosion in detail.

 As a result, it was found that a large amount of the Mn-containing compound was extruded during the extrusion process, but that the difference in the amount of deposition between the welded part and the non-welded part caused preferential corrosion of the welded part. We found that pre-precipitation of the Mn-containing compound by homogenization of the lumps prior to extrusion can reduce preferential corrosion of the welded part, and further research to complete the present invention It led to.

 The present invention provides the following means.

 (1) An aluminum alloy hollow material manufactured by porthole extruding an aluminum alloy lump containing at least 0.3 to 1.5 wt% of Mn or by porthole extrusion and drawing. An aluminum alloy hollow material, wherein the difference in electrical conductivity in each part in the longitudinal direction of the hollow material is 1.0 IACS% or less.

(2) Homogenize aluminum alloy ingot containing at least 0.3 to 1.5 wt% of Mn, and then extrude the ingot through porthole or porthole extrusion and drawing. In the method for producing a hollow material, the homogenization treatment is carried out at a predetermined temperature of 500 to 60 ° C for 0 to 24 hours, and then at a cooling rate of 100 ° C / hr or less. Cool to a specified temperature of 0-500 ° C, hold at this temperature for 4 to 48 hr and apply The method for producing a hollow aluminum alloy material according to the above (1), characterized in that:

(3) A homogenizing treatment is performed on an aluminum alloy ingot containing at least 0.3 to 1.5 wt% of Mn, and then the ingot is subjected to porthole extrusion or porthole extrusion and drawing. In the method for producing a hollow material by heating, the homogenization treatment of the lump is maintained at a predetermined temperature (T i) of 500 to 60 ° C. for 0 to 16 hours, and then the temperature is reduced from the T i temperature by 10 to 10 hours. 0 ° and cooled to C / hr in the following cooling speed _{3 5 0 ° C (T 2} ), the time up to the arrival after T ₂ temperature I \ temperature and 1 0~ 4 8 hr, T ₂ The method for producing an aluminum alloy hollow material according to the above (1), wherein the method is carried out by cooling from a temperature to a room temperature at an arbitrary cooling rate.

 (4) Homogenize aluminum alloy ingot containing at least 0.3 to 1.5 wt% Mn, and then extrude this ingot through porthole or porthole extrusion and drawing. The method for manufacturing a hollow material, wherein the homogenization treatment of the lump is maintained at a predetermined temperature of 400 to 500 ° C. for 12 to 48 hours, and then cooled to room temperature. The method for producing a hollow aluminum alloy material according to the above (1).

(5) Homogenize aluminum alloy ingot containing at least 0.3 to 1.5 wt% Mn, and then extrude this ingot through porthole or porthole extrusion and drawing. In the method for producing a hollow material, the homogenization treatment of the mass is maintained at a predetermined temperature of 400 to 500 ° C. for 0.5 to 4 hours, and then the temperature is maintained at 550 to 63 ° C. After the temperature is raised to the specified temperature and maintained at that temperature for 0.5 to 4 hours, it is cooled to 350 ° C at a cooling rate of 100 ° C / hr or less, and any cooling from 350 ° C The aluminum alloy according to the above (1), wherein the cooling is performed at room temperature at a speed. Manufacturing method of hollow metal alloy.

 (Hereinafter, the hollow material described in (1) and the production method described in (2) to (5) are collectively referred to as a first invention of the present invention.)

 (6) Mn 0.8-1.5 wt%, Fe 0.1-0.7 wt%, Sio03-0.6 wt%, CuO.0.0-0 4.5 wt%, Mg 0.0-0.3 wt%, Cr 0.0-0.3 wt%, Ti 0.0-0.1 wt% ZnO.0-0.5 Aluminum alloy lump containing one or more of wt%, Zr 0.0-0.3 wt%, Ni 0.0-0.3 wt%, and the balance Al and unavoidable impurities Is an aluminum alloy extruded tube for air conditioner piping manufactured by a porthole type continuous hot extrusion method, wherein the extruded tube has a conductivity of 39.0 IACS% or more (preferably 39.5 IACS). %), And a difference in electrical conductivity in each part in the longitudinal direction of the extruded tubing is 1.0 IACS% or less.

(7) Mn 0.8-1.5 wt%, Fe 0.1-0.7 wt%, Sio03-0.6 wt%, CuO0.0-0-0 45 wt%, MgO .0 to 0.3 wt%, Cr 0.0 to 0.3 wt%, TiO .0 to 0.1 wt.ZnO .0 to 0.5 aluminum alloy lump containing one or more of wt%, Zr 0.0-0.3 wt%, NiO0.0-0.3 wt%, the balance being Al and unavoidable impurities A method for producing an aluminum alloy extruded tube for air conditioner piping, in which a homogenization treatment is performed on the aluminum alloy, and this is extruded into a tube by a port-hole continuous hot extrusion method. After maintaining the temperature at a predetermined temperature of up to 630 ° C for 0 to 24 hours, it is cooled to a predetermined temperature of 400 to 500 ° C at a cooling rate of 100 ° C / hr or less, and this temperature is Air for 4 to 48 hours A method for manufacturing extruded aluminum alloy pipes for piping.

(8) A method for producing an aluminum alloy extruded tube for air-con piping, in which the aluminum alloy lump described in the above (7) is subjected to homogenization treatment and extruded into a tube by a porthole continuous hot extrusion method. The homogenization treatment of the mass is maintained at a predetermined temperature (T) of 500 to 60 ° C. for 0 to 48 hours, and then cooled from 1 temperature to 100 ° C./hr or less. 3 was cooled to 5 0 ° C (T ₂₎ at a rate, the time up to the arrival after T ₂ temperature T i temperature was 1. 2 to 4 8 hr, to room T ₂ temperature at any cooling rate A method for producing an aluminum alloy extruded tube for air conditioner piping, which is cooled and applied.

 (9) A method for producing an aluminum alloy extruded tube for air conditioning piping, wherein the aluminum alloy lump described in the above (7) is subjected to a homogenization treatment and extruded into a tube by a porthole continuous hot extrusion method. Wherein the homogenization treatment of the lump is performed at a predetermined temperature of 400 to 500 ° C. for 12 to 48 hr, and then cooled to room temperature. Manufacturing method of extruded aluminum alloy tube.

(10) The aluminum alloy ingot described in (7) above is subjected to homogenization treatment and extruded into a pipe by a porthole continuous hot extrusion method. A method of manufacturing, wherein the homogenization treatment of the mass is maintained at a predetermined temperature of 400 to 500 ° C. for 0.5 to 4 hours, and then is performed at a predetermined temperature of 550 to 63 ° C. After the temperature is raised to the temperature and maintained at that temperature for 0.5 to 4 hours, it is cooled to 350 at a cooling rate of 100 ° (/) 1> or less, and any cooling rate from 350 ° C A method for producing an aluminum alloy extruded tube for air-con pipes, wherein the tube is cooled to room temperature. (Hereinafter, the extruded tube material described in the above item (6) and the production method described in the above items (7) to (10) are collectively referred to as a second invention of the present invention.)

 Here, unless otherwise specified, the present invention means the first and second inventions.

 According to the method described in the above (2) to (5), the aluminum alloy ingot containing a predetermined amount of Mn is subjected to a specific homogenization treatment, whereby the aluminum alloy ingot is formed by port hole extrusion. The hollow member according to the above (1), which does not cause preferential corrosion of the welded portion, can be manufactured. This hollow material is suitable as a building material or the like.

 Further, according to the method described in the above (7) to (10), alloy components other than Mn are also specified in place of the aluminum alloy lumps used in the method described in the above (2) to (5). The above-mentioned (6), which does not cause preferential corrosion in the welded portion by subjecting the aluminum alloy ingot to homogenization treatment similar to the method described in the above (2) to (5). The extruded tubing described can be manufactured. This pipe is suitable for air conditioner piping. BEST MODE FOR CARRYING OUT THE INVENTION

 First, the alloy components of the hollow material and the extruded tube material of the present invention will be described.

Mn is an element that contributes to strength improvement without deteriorating corrosion resistance. In the first invention, if the content is less than 0.3 wt%, the effect cannot be sufficiently obtained, and if the content exceeds 1.5 wt%, the effect is saturated, and the deformation resistance during hot working increases. As a result, port hole extrudability decreases. Therefore, its content should be 0.3-1.5 wt% (preferably 0.5-: L.3 w t%).

 In the second invention, if the content of Mn is less than 0.8 wt%, the effect is small, and if it exceeds 1.5 wt%, the effect is saturated, and the deformation resistance during hot working increases. As a result, port hole extrudability decreases. Therefore, its content is set to 0.8 to 1.5 wt% (preferably 0.9 to 1.2 wt%).

 Hereinafter, in the second invention, each of the alloy components including Mn is determined in consideration of the strength, corrosion resistance, workability, and the like required for the material for automotive air conditioner piping, and that porthole extrusion is easy. .

Fe and Si are forces ^s contained in general aluminum alloys in a small amount, and these elements reduce the amount of solid solution of Mn and simultaneously form A 1 and an intermetallic compound during fabrication, This has the effect of refining the recrystallized structure, and it is desirable that Fe and Si be appropriately contained. However, if the content exceeds 0.7 wt% in 6 and 0.6 wt% in 3%, a huge intermetallic compound is formed, and the formability and corrosion resistance are reduced. Therefore, the contents of Fe and Si are respectively 0.1 to 0.7 wt% (preferably 0.2 to 0.6 wt%) and 0.3 to 0.6 wt% (preferably 0.3 to 0.3 wt%)

 Cu contributes to improvement in strength. Cu dissolved in the substrate enhances the spontaneous potential and slightly improves the corrosion resistance. However, when the content exceeds 0.45 wt%, the compound containing Cu is selectively precipitated at the crystal grain boundaries during the extrusion process and the like, and the intergranular corrosion increases and the port hole extrudability decreases. . Therefore, the content of Cu is set to 0.0 to 0.45 t% (preferably 0.0 to 0.25 wt%).

Although Mg contributes to solid solution and contributes to strength improvement, it significantly reduces hot deformation resistance. If the Mg content exceeds 0.3 wt% in addition to the Mn content, the porthole extrudability decreases. Therefore, the content of Mg should be 0.0 to 0.3 wt% (preferably 0.0 to 0.3 wt%).

 Cr is a force that is effective in refining the crystal structure. If its content exceeds 0.3 wt%, a coarse A1-Cr compound is formed and the formability is impaired. Therefore, the Cr content is 0.0. To 0.3 wt% (preferably 0.0 to 0.05 wt%).

 Ti refines the crystal structure with a small amount of Ti. If its content exceeds 0.1 wt%, extrudability will be reduced and a giant intermetallic compound harmful to moldability will be produced. Therefore, the content of Ti is set to 0.0 to 0.1 wt% (preferably 0.0 to 0.05 wt%).

 Although Zn is expected to have a slight strength-improving effect, a large amount of Zn induces a decrease in corrosion resistance. Therefore, the content of Zn is set to 0.0 to 0.5 wt% (preferably 0 to 0. lwt%).

 Zr is effective in refining the crystal structure, but a large amount of it decreases extrudability and formability. Therefore, the content of Zr is set to 0.0 to 0.3 wt% (preferably 0.0 to 0.05 wt%).

 Ni has a slight strength-improving effect, but the addition of a large amount reduces extrudability and formability. Therefore, the content of Ni is set to 0.0 to 0.3 wt% (preferably 0.0 to 0.05 wt%).

 Here, that the content of the alloy component is 0 wt% means that the alloy component is not contained at all.

The aluminum alloy used for the extruded tube material of the second invention contains Cu, Mg, Cr, Τi, Ζη, in addition to containing the aforementioned predetermined amounts of Mn, Fe, and Si. Selected from the group consisting of Ζ r and Ν i One or two or more, and the balance consists of A1 and unavoidable impurities.

 The aluminum alloy composed of the above components can be sufficiently extruded into an air-conditioner piping material having a predetermined shape by a port hole extrusion method. In addition, the aluminum alloy has a uniform fine recrystallized structure, strength and ductility similar to those obtained by annealing a drawn tube in the extrusion process (immediately after leaving the die).

 In the present invention, the electrical conductivity of the extruded tubing is defined as the electrical conductivity of each part along the entire length in the longitudinal direction of the extruded tubing, and the electrical conductivity difference in the longitudinal direction of each extruded tubing (the maximum value of the electrical conductivity) in the second invention The difference between the minimum value and the minimum value is specified in order to avoid preferential corrosion of the weld.

 The present inventors have obtained the following knowledge about the cause of preferential corrosion at a welded portion.

 In the DC or hot-top construction, most of Mn is in solid solution in the aluminum solid phase because it is immediately cooled with water and solidified immediately after solidification.均質 In the homogenization treatment applied to the lump, Mn does not precipitate much because it is maintained at a high temperature close to the solidus temperature for the purpose of eliminating micro-segregation, separating crystallized matter, spheroidizing, etc. . Also, in the cooling step after holding at a high temperature, Mn hardly precipitates here because the cooling rate is relatively high. Here, regardless of the presence or absence of homogenization, the lump is subjected to the next reheating and extrusion process.

 As the Mn-containing compound, Al—Mn-based compounds, Al— (Fe, Mn) -based compounds, A1- (Fe, Mn) -Si-based compounds, etc. are known. Put out.

Normally, the extrusion temperature is about 400 to 500 ° C. This temperature range is the temperature at which the supersaturated solid solution of Mn tends to precipitate. And during extrusion The study by the present inventors has revealed that the precipitation rate of the steel is remarkably large because the precipitation is promoted by the processing.

 In other words, in the process in which a large strain is continuously applied as in the case of extrusion, the diffusion of alloy elements is remarkably accelerated, and as a result, compound precipitation is accelerated.

 For example, the extrusion time of a billet having a length of about several tens of cm is several minutes at most, and precipitation progresses remarkably in these few minutes. Here, since the rear end of the billet is subjected to distortion for a long time, the amount of precipitation is larger than that of the front end of the extrusion. If the same heating is performed for several minutes without processing, the Mn-containing compound hardly precipitates.

 Originally, the diffusion rate of transition metal such as Mn in A1 is extremely low, but the precipitation of Mn (dynamic precipitation phenomenon) remarkably progresses due to the continuous application of strain.

 The fact that the precipitation of the Mn-containing compound is large in the latter half of the extrusion can be confirmed by both observation with a transmission electron microscope and measurement of conductivity. That is, the conductivity increases as the amount of precipitation increases, and the conductivity of the Mn-containing extruded aluminum alloy tends to increase from the front end to the rear end, and the difference is usually at least 2 IACS% or more. is there.

As described above, the precipitation of the Mn-containing compound proceeds more at the rear end side of the extruded tubing material.However, when extruding multiple billets continuously, the welding mechanism is formed by the following mechanism. Difference between the non-welded portion and the non-welded portion. In other words, in the continuous extrusion process of an aluminum alloy using a porthole die, after the first billet has been extruded, the first billet remaining in the space created by the die hole and the welding chamber (chamber) is formed. In the aluminum alloy, the precipitation of Mn progressed most at the end of extrusion, and the Mn solid solution A second billet with a high degree is placed adjacent by extrusion. In this state, extrusion of the second billet is started, but at the beginning of the extruding of the second billet, the aluminum alloy of the first billet remaining in the welding chamber and the port hole is discharged. As a result, the aluminum alloy of the second billet is discharged to the non-welded portion, and the portion occupied by the second billet gradually increases.

 As described above, in the exchanging portion of the billet, in the extruded tube material, the welded portion is formed of the aluminum alloy at the rear end of the preceding billet, and the non-welded portion is formed of the aluminum alloy of the succeeding billet. You. This configuration continues until the end of extrusion of the subsequent billet while the width of the welded portion is narrowed.

 As described above, due to the progress of precipitation during extrusion, the deposition proceeds in the non-welded portion in the latter half of extrusion, and the difference in the deposition state between the welded portion and the non-welded portion becomes smaller. This configuration is the same even if the number of extrusions increases.

 As described above, a pattern in which the Mn-containing compound is largely deposited in the welded portion and the Mn solid solubility is relatively high in the non-welded portion becomes prominent at the extrusion tip side. Comparing the electrochemical properties of the two, the welded part where the precipitation of the Mn-containing compound has progressed has a lower potential, and the welded part is sandwiched between non-welded parts with a noble potential. In a corrosive environment, the welded part is preferentially corroded in a corrosive environment, causing corrosion problems.

 In order to prevent preferential corrosion of the welded portion, the present inventors have made it effective to reduce the difference in solid solution amount of Mn between the front end side and the rear end side of the extruded billet before extrusion. Thus, the present invention has been completed.

The present inventors have found that it is effective to precipitate a Mn-containing compound during the homogenization treatment in order to reduce the difference in the amount of solid solution of Mn. That is, in the lump in which the precipitation of the Mn-containing compound has already progressed, excessive precipitation does not progress in the extrusion process. And adjust the homogenization conditions If the Mn-containing compound is precipitated appropriately, there is no large difference in conductivity between the front and rear ends of the extruded tubing, and between other parts, and corrosion of the welded portion is not caused. Dramatically suppressed.

 In the second invention, in the extruded material in which the effect of suppressing preferential corrosion of the welded portion is clear, the electrical conductivity of each part of the extruded material is 39.0 IACS% or more, preferably 39.5 IACS% or more. . In other words, preferential corrosion of the weld cannot be sufficiently suppressed unless all the longitudinal parts of the extruded material achieve 39.0 IACS% or more.

 Ideally, the precipitation state of the Mn-containing compound in the extruded tubing material is exactly the same from the extruded tip to the extruded end. However, in practice, if the difference is small, there is almost no selective corrosion of the weld. As described above (the above (1) and (6)), if the difference in conductivity is 1.0 IACS% or less, preferably 0.6 IACS% or less, higher reliability for corrosion resistance is obtained. Property is obtained.

 In the present invention, the difference in the electrical conductivity of each part of the hollow material or the extruded tubular material is a difference between the maximum value and the minimum value of the electrical conductivity of all samples obtained by cutting the hollow material or the tubular material in the longitudinal direction.

 By the way, in the extruded billet in which a large amount of the Mn-containing compound is finely precipitated, since the fine precipitate is dissolved in the base material at an extremely early stage of the extrusion, the precipitate must be coarsely precipitated. . In order to control the precipitation of the coarse Mn-containing compound, the homogenization treatment conditions are described in the above items (2) to (5) and (7) to (10).

In the method described in the above (2) or (7), first, a relatively high predetermined temperature of 500 to 63 ° C. is maintained for 0 to 24 hours, and then 100 ° C./hr Cool at the following cooling rate. Temperature rise process in this heat treatment The Mn-containing compound that precipitates during the holding process grows relatively coarsely during the cooling process. Here, when the cooling rate is set to be higher than 100 ° C./hr, a large amount of new precipitates are deposited. However, the precipitates are so fine that they are easily dissolved again as described above. Also, higher cooling rates are difficult in furnace cooling and are not practical from an industrial point of view. A cooling rate of 50 ° C / hr or less is particularly preferred. Thereafter, the temperature is maintained in the temperature range of 400 to 500 ° C. In this temperature range, the Mn-containing compound is most easily precipitated in the A 1 -Mn-based alloy, and the amount of precipitation is further increased during this holding process. Increase. The holding time at the above temperature is required to be 4 hours or more for the purpose of increasing the amount of precipitation, and if it exceeds 48 hours, the precipitation effect is saturated and uneconomical, so the upper limit is 48 hours. The method described in the above (2) or (7) is a method in which an appropriate precipitation state is revealed by gradually cooling after maintaining at a high temperature, and thereafter, the precipitation amount is further increased by maintaining the temperature in the range where precipitation is most easily performed. On the other hand, the method described in the above (3). (8) is a method in which precipitation proceeds only in a slow cooling process from a high temperature. The reason for setting the cooling rate to 100 ° C./hr or less by this method is the same as the reason in the above (2) and (7). Ί reason for defining the T ₂ at slow cooling process, from (5 0 0~ 6 3 0 ° C) to T ₂ to 3 5 0 ° C is 3 5 0 ° Do precipitated M n containing compound mostly less than C This is because there is no point in specifying the cooling rate. In this process conditions, to influence the deposition amount and deposition state, mainly from 5 0 0~ 6 3 ◦ ° C when us (Ί) down to _{3 5 0 ° C (T 2} ) This is a process. If the time of this process is short, it is difficult to obtain a desired precipitation state, and if it is too long, the effect is saturated and uneconomical. Therefore, the time from reaching the T i temperature to reaching the T ₂ temperature is defined as 12 to 48 hr.

The method according to the above (4) or (9), wherein the precipitation proceeds most 400 This is a method of increasing the amount of precipitates by maintaining the temperature at 5500 ° C. for a long time.

 When a highly supersaturated gunshot mass is maintained in this temperature range, fine precipitates are initially deposited, and then the precipitates are coarsened.

 If the treatment time is less than 12 hr, most of the precipitates are fine and easily re-dissolved. If the treatment time is more than 48 hr, the increase in the amount of precipitates is saturated and uneconomical. Therefore, the retention time is defined as 12 to 48 hr.

 In the method described in the above (5) and (10), a large number of fine precipitates are deposited while maintaining the temperature at a predetermined temperature of 400 to 500 ° C., and then, 550 to 630. (This is a method of coarsening the fine precipitates in the process of gradually cooling to 350 ° C. after maintaining at a predetermined temperature.

 Since the purpose of maintaining the predetermined temperature of 400 to 500 ° C. is to form fine precipitates, the holding time is set to a short time of 0.5 to 4 hr. Holding at a predetermined temperature of 550 to 63 ° C, if held for a long time, will cause the fine precipitates, which are nuclei, to disappear, so the holding time is also specified as a short time of 0.5 to 4 hr. I do.

 The cooling rate after maintaining at a predetermined temperature of 550 to 63 ° C shall be 100 ° C / hr or less, which is effective for expanding the size of existing precipitates. The reason for limiting the cooling rate to cooling to 350 ° C is that precipitation hardly occurs below 350 ° C.

According to the present invention, it is possible to obtain an aluminum alloy hollow material in which there is no difference in the structure (such as the amount of precipitated Mn) between a welded portion and a non-welded portion in porthole extrusion and preferential corrosion of the welded portion is prevented. The hollow material can be easily manufactured by subjecting a lump to a predetermined homogenization treatment to precipitate Mn in a coarse compound. Further, according to the present invention, it is possible to obtain an aluminum alloy porthole extruded pipe material for air conditioner piping in which preferential corrosion of a welded portion is improved, and the extruded pipe material is subjected to a predetermined homogenization treatment for a lump to reduce the alloy element. It can be easily manufactured by precipitating the compound containing Mn coarsely. Example

 Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

 (Example 1)

 Alloy Nos. 1 to 8 having the compositions shown in Table 1 were formed into a 6-inch outer diameter extruded round bar by the DC forming method, of which alloys Nos. After heating at ° C for 4 hr, the furnace was cooled to 350 ° C at a cooling rate of 30 C / hr, then taken out of the furnace and sprinkled with a sprinkler. The alloy ingots of Nos. 6 and 7 were heated at 585 ° C for 4 hours, cooled to 350 ° C at a cooling rate of 30 ° C / hr, then taken out of the furnace and sprinkled with a sprinkler.

 (Example 2)

 Alloy Nos. 1 to 8 having the compositions shown in Table 1 were formed into a 6-inch outer diameter round rod for extrusion by DC fabrication, and the resulting alloy was obtained at 530 ° C. Heating was performed for 6 hours, and then the furnace was cooled to 350 ° C at a cooling rate of 30 ° C / hr, then taken out of the furnace, and cooled with a sprinkler.

 (Comparative Example 1)

Alloy Nos. 1 to 8 having the compositions shown in Table 1 were made into a 6-inch outer diameter extruded round bar by using the DC method, and alloy Nos. 1 to 5 and 8 were After heating at 600 ° C for 16 hours, it was quickly transferred out of the furnace, sprinkled with a sprinkler, and cooled at a rate exceeding 100 ° C / hr. The alloy ingots of Nos. 6 and 7 were heated at 585 ° C for 8 hours, quickly transferred out of the furnace, sprinkled with a sprinkler, and cooled at a rate exceeding 100 ° C / hr.

 The lump produced in the steps of Examples 1 and 2 and Comparative Example 1 was cut into a predetermined length to obtain an extruded billet, which was obtained by a porthole extrusion method with a side of 12.0111111 and a wall thickness of 1.4. It was extruded into a hollow rectangular section with a square cross section of 0 mm. The number of extruded hollow sections was one, the port holes were two, and the welds were at the centers of the opposite sides. The extruded billet was reheated to 44 ° C using an induction heater, and the extruded material was forcibly air-cooled with a fan. Three extruded billets were prepared for each alloy and extruded continuously.

 For various evaluations, a hollow section corresponding to the third extrusion billet was provided.The section up to 5 m from the head of this hollow section was excluded because many subsequent billets were mixed in, and the remaining sections were excluded. Sampled from the part. The conductivity of each sample was measured by the four-terminal method, and the conductivity difference ΔE C between the front end side and the rear end side of the hollow profile was obtained.

The sample was subjected to a CASS test (JIS-H-86861) for 200 hours, and the state of preferential corrosion of the welded portion after the test was visually observed and evaluated on a three-point scale (A: no preferential corrosion, B: Some preferential corrosion, C: preferential corrosion). When there was a difference between the front end and the rear end of the hollow section, the one with the worse corrosion was evaluated. Table 2 shows the results. table 1

(Note) Unit: wt%.

Table 2

(Note) A: No preferential corrosion occurs at the welded part Example of dispensing application 2 Table 2 (Continuing Homogenization treatment conditions Extrusion end rear end Conductivity difference of preferential corrosion

No IAC S% CASS

Book 530 ° C 0.7 A

 X 6 hr heating and furnace cooling

 → 350 ° C water spray cooling

 20.5 A

30.5 A

40.4 A

0.8 A

0.7 A

7 0.7 A

8 0.6 A

(Note) A: No preferential corrosion occurs at the welded part Table 2 (continued)

 (Note) B: Some preferential corrosion is observed at the weld.

C: Priority corrosion evident in welds From Table 2, it can be seen that in all of the examples of the present invention, ΔΕ is 1.0 IACS% or less, and the precipitation amount of Mn is hardly different between the front end side and the rear end side of the hollow material. The conductivity was higher on the rear end side than on the extrusion front end side of each billet in each case, and no preferential corrosion was observed in the welded portion of any material.

 This is because Mn was coarsely precipitated during the homogenization of the lump. In contrast, in each of the comparative examples, the value of Ec exceeded 1.0 IACS%, and the conductivity was higher on the rear end side than on the front end side.

 This is because a material in which a large amount of Mn was dissolved was extruded, and there was a difference in the amount of Mn precipitated at the front and rear ends of the extrusion.

 Table 2 shows the results of the evaluation of the tip part where the degree of corrosion is severe in the CASS test.

 In the case of rank C, the corrosion of the welded portion was found to penetrate even though the wall thickness was as thick as 1.4 mm.

 (Example 3)

 Alloy No. 2 having the composition shown in Table 1 was formed into a 6-inch outer diameter extruded round bar by DC fabrication, and the alloy was heated at 610 ° C for 8 hours. The furnace was cooled to 350 ° C at a cooling rate of 25 ° C / hr, then transferred outside the furnace and sprinkled with a sprinkler.

 (Example 4)

 Alloy No. 2 having the composition shown in Table 1 was formed into a 6-inch outer diameter extruded round bar by DC fabrication, and this alloy was heated at 450 ° C for 36 hr. Then, it was transferred outside the furnace and allowed to cool.

 (Example 5)

Alloy No. 2 having the composition shown in Table 1 was prepared by a DC The extruded round bar was made into a lump, heated at 580 ° C for 6 hours, cooled in a furnace at a cooling rate of 40 ° C / hr to 420 ° C, and cooled to 420 ° C. After heating at ° C for 18 hr, it was transferred outside the furnace and allowed to cool.

 (Comparative Example 2)

 No. 2 alloy was formed into a 6-inch outer diameter round bar for extrusion by DC forming, and the obtained block was homogenized at 6100 ° C for 16 hours. Was transported out of the furnace, cooled for a short time by a fan, and then sprinkled by a sprinkler at a cooling rate of 16 CTCZhr or more.

 Each lump obtained in Examples 3 to 5 and Comparative Example 2 was cut into a predetermined length to obtain an extruded billet, which was heated to 450 ° C. by an induction heater. Hot-extruded into a tube with an outer diameter of 18.6 mm and a wall thickness of 2.3 mm (hereinafter referred to as 18.6 πιπι 0 χ 2.3 ιηιη), and the extruded product was fan-shaped. More air cooled.

 Extrusion was performed using a 4-port die with two extruded products and welds formed at four locations in the circumferential direction. Five extrusion billets were prepared for each alloy, and these were continuously extruded.

 For the sample, the third extruded billet part is extruded tubing, and the fourth and fifth extruded billets are each subjected to one-pass and two-pass drawing after extrusion, followed by one-pass drawn tubing and two-pass. The drawn tube material was collected and subjected to various evaluations.

The one-pass drawn tube material, 1 8. 6 mm <zi X 2. 3 a Paiiotaiotaita ^iota extruded tube material 1 6. O mm x 2. Drawing process to O mm (processing rate 2 5.3%), and the The two-pass drawing tubing was produced by further drawing the above-mentioned one-pass drawing tubing to 13.8 mm ^ 1.75 mmt (processing rate 25.0%). The total drawing rate of 2-pass drawn tubing is 44.0%. Said A draw bench was used for the drawing process.

 The extruded tubing and the extraction tubing obtained in this way were the same as in Examples 1 and 2, except for 5 m from the front end, and the remaining front end, rear end, and the middle part Samples were taken from locations.

 The conductivity at the front end and the rear end of this sample was measured by the four-terminal method, and Δ 求 め C was obtained in the same manner as in Example 1.

 The corrosion resistance of the sample at the front end, middle, and rear end was examined by a 200 hr CASS test. The appearance after the test was visually observed and evaluated according to the same criteria as in Example 1.

 Table 3 shows the results. Table 3

(Note) The lower row shows the CASS test results for the front end / middle / rear end. As is clear from Table 3, the examples of the present invention (Examples 3, 4.5) had an EC of less than 1.0 IACS% for both the extruded tube and both drawn tubes, and the CASS test results were all ranked A. No preferential corrosion of the weld was observed. There was no particular difference between the one-pass drawn material and the two-pass drawn material.

 In contrast, in Comparative Example (2), which was homogenized by the conventional method, ΔEC exceeded 1.0 IACS% for both the extruded tubing and both drawn tubing. In the middle part, severe preferential corrosion was observed at the weld.

 The mechanical properties of the extruded hollow sections produced in Examples 1 and 2 and the extruded pipes or drawn pipes produced in Examples 3 to 5 were examined, all of which have the required properties such as tensile strength and elongation. Met.

 (Example 6)

Alloy A having the composition shown in Table 4 was formed into a 6-inch outer diameter round bar for extrusion by DC forming, and the obtained block was subjected to the homogenization treatment shown in Table 5 and homogenized. The electrical conductivity of the lumps after the chemical treatment was measured. Table 5 shows the results. In the homogenization treatment, as an example of the present invention, the temperature was maintained at 600 ° C. for 8 hours, and then cooled in a furnace at a cooling rate of 50 ° C./hr to 450 ° C., followed by 450 ° C. C for 24 hours, air cooling to room temperature after holding at 450 ° C, and as a comparative example 3, quickly remove the lump from the furnace after holding for 8 hours at 600 ° C Water cooling (cooling rate> 100 ° C / hr) to normal temperature with an ink clarifier, and as a comparative example 4, after holding at 600 ° C for 24 hours, use a sprinkler at room temperature as in Comparative Example 3. Cooling in three ways. Table 4 l σ C r 7 _n i 2 _r N j Δ 1 fi In 手 π ηα 0, 36 0.12 1.07 0.00 o oo 0, 00 0.01 0.00 o.00

R 6 Γ / h Ψ ο.10 0.37 0.i 1 1.oc 0, 00 0.00 0.01 0 01 0.00 0.00 c 0 2 0 | 2 1 07 0.00 0.00 o.00 0.01 0.00 0.00 π υ υ. Υ υ n ij 0. Ofi 0 Ofl u 0.00 00 0.00 0 01 Q 00 o. Oo

 ρ 手 ο οο 0. 0.0.12 J.02 0.00 0.00 0.00 0.01 00 0.00

 6 in ί 0.05 0.43 0.06 0.97 0.00 0.00 0.00 0.01.0.00 o.oo

6 inches 0.09 0.3? 0.11 1.08 0.01 0.00 0.01 0.01 0 00 0.00

11 π oq 0.39 0.12 0 go 0.00 0.00 o oo 0.01 o oo o.00 r l 6 inches ώ 0.11 0.40 0, 12 s 03 0.30 0.00 o.oo 0.01 o.oo 0.00 Remaining

J 6 inch 0.45 0.15 0.45 1.11 0.00 0.00 0.00 0.01 0.000 0.00

 K 6ί> ί 0.17 0.3 0.13 1.05 0.00 0.00 0.20 0.01 0.00 0.00 and 6 inches φ 0.10 0.38 0.I I 0.5! 0.00 0.00 0.00 0.01 0.00 0.00 Remaining

U 0.09 0.38 0.12 1.33 0.00 0.00 0.00 0.01 0 00 0.00

 N 6 Φ 0.I I 0.37 0.13 1.55 0.00 0.00 0.00 0.01 0.00 0.00

 0 6 H 0.10 0.34 0.14 1.09 0.48 0.00 0.00 0.01 () .00 0.00

P 0.28 0.30 0.55 1.08 0.00 0.00 0.00 0 01 0.00 0.00

Table 5

 Conductivity measurement after homogenization

Item Homogenization conditions Conductivity Extrusion

 Number between front and rear end Front end side Middle end Rear end side

 EG difference (N-th) (No.1) (No.4) (No.7) AEC

3 冃 40. 7 40. 7 4 1. 2. 0.5

60 O 8hr + 45 O x 24hr sky

Wood invention example (600-450: Cooling rate 50 ° C / hr) 39.3S1ACS 5 |; 1 40.8 40.8 4 1.4 0.6

 3 pieces 39.1 39.4 40.3 1.2 Comparative example 3 60 O: x 8 hours after holding the sprinkler losing ifr 36.6¾IACS 5 pieces S 39.1 39.4 40.2 1.1

3 pieces 40.1 40.3 4 1.4 1.3 Comparative example 4 6001CX Sprinkler after holding for 24 hours ¾Water cooling 37.7¾IACS Fifth piece 39.7 40.3 40.9 1.2

As is clear from Table 5, the lump treated in the present invention has higher conductivity than the lump treated in Comparative Examples 3 and 4, and the precipitation of the Mn-containing compound is progressing. Compared with the conductivity (36.5 IACS%) before the homogenization treatment, in Comparative Examples 3 and 4, precipitation hardly progressed from the solid state. The lump cut into a predetermined length was homogenized under each condition, and then hot-extruded continuously into 5 mm each of 8 mm 0 x 1.0 mm tube using a 4-port hole die. . There were four welds in the extruded tube in the circumferential direction and continuous in the longitudinal direction. The billet was heated to 420-460 ° C using an induction heater. The extrusion speed of the tubing was 60 m / min. The tube immediately after extrusion was water-cooled, the adhering water droplets were removed by blowing, and the tube was wound up with an in-line coiler.

 The coiled extruded material was cut to a fixed length of about 6 m, stretched (remanufactured), and the required parts were sampled.

 For the third and fifth parts of the continuous extrusion billet, sampling was performed at seven locations every 30 m from the tip end to the rear end of the extrusion, and the conductivity, mechanical performance, and corrosion resistance were investigated. did. The conductivity was measured by a four-terminal method.

 The workability of the second and fourth parts of the continuous extrusion billet was investigated in consideration of application to air conditioner piping. The results are shown in Table 5.

 As is evident from Table 5, in all cases, the conductivity tends to increase after extrusion than after homogenization and further from the extrusion front end to the extrusion rear end.

In order to compare the conductivity of the extruded tubing in the longitudinal direction, the difference between the conductivity of the extruded tubing at the front end and the rear end (denoted as AEC) is also shown in Table 5. △ The EC exceeded 1% in Comparative Example 34, and remained at 0.50.6% in Examples of the present invention.

 This indicates that the phenomenon in which precipitation proceeds in the extrusion process and the amount of precipitation increases in the latter half is suppressed by the homogenization treatment in the present invention.

 Next, the tensile properties were investigated.

 For the sample near the center in the longitudinal direction of the extruded tubing, the tensile strength (T S), 0.2% strength (Y S), and elongation (E 1) were measured. Table 6 shows the results.

 Table 6

As is clear from Table 6, there is no difference in the tensile properties between the present invention example and the comparative example, and both satisfy the tensile properties required for the current pipe material. Therefore, desired properties and workability can be obtained with the tube material of the present invention as with the existing materials. Next, we focused on the corrosion of the welded part, which is a concern in porthole extruded tubing, and investigated the corrosion resistance of this part. For all materials, the corrosion test was performed for 240 hours using the CASS test method specified in JIS-H-8681. Assuming automotive air conditioner piping, only external corrosion resistance is a problem, so the end of the test tube was sealed to prevent corrosion from inside the tube.

 As a result of washing and visual observation of the sample after the corrosion test, the non-welded portion (the portion other than the welded portion) exhibited pitting corrosion that did not lead to penetration. No particular difference was observed between the example and the comparative example. This pitting condition was at a level comparable to that of the current tubing (3003 alloy manufactured through the extrusion, drawing and annealing processes) that was separately tested. The preferential corrosion of the weld was evaluated by classifying the degree into five levels.

 Table 7 shows the results.

 C A S S test: 240 h

 Evaluation of preferential corrosion> ◎ No corrosion

 Slightly shallow corrosion (shallower than pit depth) Corrosion less than 10% of total length

 Corrosion in 10 to 50% of all

Corrosion in more than 50% of As is evident from Table 7, for all of the materials, the preferred corrosion of the deposits was significant at the tip end of the extrusion, and hardly occurred at the end of the extrusion. However, the occurrence degree of preferential corrosion is remarkably different between the present invention example and the comparative example.In other words, the comparative example exhibits preferential corrosion in many samples, whereas the present invention example shows the preferential corrosion at the extrusion tip side. Limited to a part.

 The materials marked with ▲ or X often have through holes in the preferentially corroded part of the welded part. From this point, when the pipe material of the comparative example is applied to automobile air-con pipes, it is not desirable because corrosion may cause early leakage due to corrosion. On the other hand, the tube material of the present invention example can be sufficiently used except for a very small part on the side of the extrusion tip.

 Next, the bending workability and end workability required for automotive air conditioner piping were examined.

 The bending workability was tested using an NC bending machine at two levels of bending angles of 45 degrees and 90 degrees and a bending radius of 25 mm.

Samples of the extruded tubing of the present invention and comparative examples 3 and 4 were 30 cm in length from the seven places at three equal intervals in the longitudinal direction. A sample was taken. Table 8 shows the results.

Table 8

 〇: no abnormality X: -normal As can be seen from Table 8, in each of the present invention, Comparative Examples 3 and 4, stable bending was performed without generating cracks, dents, and rough skin. did it.

 As described above, the conventional 0.3-alloy annealed tubing of Eve and the tubing of the present invention have the same characteristics, but the elongation value of the tubing of the present invention exceeds 30% and the crystal structure further increases. Is uniform and fine.

 Next, the terminal workability will be described.

End processing of type B in Fig. 2 (B) and type C in Fig. 2 (C) This is a new type of bead processing called shaft seal bead, whose use is remarkable. That is, as shown in Fig. 3 (A), type B is processed by punching (combination of pipe expansion and contraction) in the entire process, and type C is processed as shown in Fig. 3 (B). Punching is performed partway, and finally rolling is performed to form a groove.

 Table 9 shows the samples of the extruded tubing material of the present invention, each of which had a length of 2 cm and a length of 20 cm, respectively. The result of performing a processing test is shown. The terminal addition was indicated by the presence or absence of abnormalities in the sample after the test.

Table 9

〇: No abnormalities X: Always present As shown in Table 9, any position in the longitudinal direction of the extruded material (from the front end to the middle to the rear end) can be obtained for the end pipes of any of the types A to D according to the present invention. ) However, it can be seen that sound processing can be performed without causing problems that are particularly problematic in dimensions and appearance.

 Since the dimensional accuracy of the end processed portion is greatly affected by the dimensional variation of the extruded tubing, the variation of the outer diameter and wall thickness of the extruded tubing was examined using the tubing of the present invention.

 As a result, the dimensions of the extruded tubing are as follows: the maximum outer diameter is 8.05 mm, the minimum is 7.92 mm, the maximum wall thickness is 1.04 mm, and the minimum is 0.97 mm. It is almost the same as. In addition, if the tube material dimensions are at this level, the extruded tube material of the present invention can be sufficiently used as an air conditioner pipe for an automobile.

 Next, the surface condition of the processing end part of type B (in Fig. 2 (B), indicated by 1; the pipe part that has not been affected is indicated by 2) was examined by a scanning electron microscope (SEM). I was more informed and compared with the existing tubing.

 As shown in the photo of Fig. 4 (A), the processing end (1) of the current pipe has a longitudinal line due to minute streaks (groove-like defects) formed on the surface of the pipe during drawing. A significant number of streaks were inevitably present. On the other hand, as shown in the photograph of FIG. 4 (B), the processing end portion (1) of the tube material of the present invention exhibited an extremely smooth surface state without such fine streaks.

 Next, the surface condition of the end processed part of type C (in Fig. 2 (C), indicated by 3; the pipe part that has not been affected is indicated by 4) was compared with the existing pipe material. At the processing end (3) of the existing pipe material, a large number of stripped pieces of aluminum material were generated in the groove (5) formed by rolling. It is presumed that this rolling peeling is affected by streak defects and minute streaks during drawing.

On the other hand, the end portion (3) of the pipe material of the present invention is not It had a beautiful and beautiful processed surface.

 As described above, similar results were obtained not only when the tube was extruded at an extrusion speed of 60 m / min, but also when extruded at a high speed of 100 m / min.

 As described above, the extruded tubing material of the present invention has the strength performance, corrosion resistance, bending / end workability, extrudability, etc. to be provided as automotive air-con piping, and is a material suitable for automotive air-conditioning piping. It is.

 Regarding mechanical properties and workability, there is a problem with the force and corrosion resistance that do not have any problems even with conventional porthole extruded tubing, because preferential corrosion occurs at the welded portion. On the other hand, in the porthole extruded pipe material of the present invention, problems such as preferential corrosion do not occur by performing a predetermined homogenization treatment on the ingot.

 INDUSTRIAL APPLICABILITY The pipe material of the present invention does not require drawing and annealing, simplifies the process and reduces manufacturing costs, and has good surface quality, and is suitable for automotive air conditioner piping materials.

 (Example 7)

Alloy B having the composition shown in Table 4 was formed into a 6-inch OD extruded round bar by DC sintering, kept at 600 ° C for 4 hours, and then cooled at 50 ° C / The mixture was cooled in a furnace at 450 ° C. for hr, kept at 450 ° C. for 24 hr, and air-cooled to room temperature after keeping at 450 ° C. for homogenization.切断 After cutting the lump to a predetermined length, heat it by induction heating to 44 to 460 ° C, and use a 4-port or 3-port port hole die, each with 8 mm ø X 1 mm ' thin tubing or 1 2. 7 mm ø 1. 2 πι πι the ^ι the large diameter tube material which it by five extrusion rate of tube material was continuously extruded in 4 0 m / min.

The extruded material was fan-cooled immediately after extrusion, cut and stretched as it was straight. Conducted on the obtained round bar and lump and extruded tube material.Similar to row 6. 銪 The conductivity of the lump, the difference in conductivity between the extruded tube material and the rear end of the extruded part, tensile properties, corrosion resistance, Various properties of the preferential corrosion property and workability of the welded part were examined. As a result, a result similar to that of Example 6 was obtained.

 (Example 8)

 Alloys having the compositions shown in Table 4 (:, D were made into a 9-inch outer diameter extruded round bar by the DC manufacturing method, and alloys E and F were manufactured by the DC manufacturing method. Extrusion rods with a diameter of 6 inches were extruded into a lump and kept at 600 ° C for 4 hours, then cooled in a furnace at a cooling rate of 50 ° C / hr to 450 ° C, and then cooled. The temperature was maintained at 450 ° C for 10 hours, and after the temperature was maintained at 450 ° C, air-cooling was performed to room temperature to perform a homogenization process.

 After the homogenization treatment, each piece was cut into a predetermined length to form an extruded billet, and each piece was extruded continuously by a porthole extruder five by five.

 The 9 inch pellets were extruded into 16 mm <^ xl. 2 mm 'thick tubing or 8 mm x 1 mm' thin tubing. In this extrusion, four products were simultaneously extruded at three welded parts.

 The 6-inch billet was extruded into a large-diameter tube of 12.7 mm x 1.2 mm 'or a small-diameter tube of 8 mm 0 x lmm' different in size from the 9-inch bottle. This extrusion is a two-piece extrusion and has three welds.

The billet was heated during extrusion using a gas burner type reheating furnace for 9-inch materials and induction heating for 6-inch materials. The billet heating temperature was set at 44 to 48 ° C. The extrusion speed was 25 m / min for a tube material of 8 mm outside S in the case of 9 inches, and 40 m / min for the others. The material immediately after extrusion was cooled with a fan, cut straight, without coiling, and stretched. For the obtained rods and extruded tubing, various performances required for automobile air-conditioning piping, such as the electric conductivity of the lump, the conductivity of the extruded tubing, the difference in conductivity between the rear end of the extruded part, and the tensile properties , Corrosion resistance, preferential corrosion at welds, and end workability were investigated.

 In addition, prototypes of pipes were manufactured with only the homogenization treatment conditions changed, and various investigations were conducted in the same manner. One of the changes in the homogenization treatment conditions was that the cooling rate to 450 ° C after holding at 600 ° C was set to 25 ° C / hr. The retention time at ° C was set to 4 hr or 16 hr.

 As a result, a result similar to that of Example 6 was obtained.

 (Example 9)

 It will be explained that the tubing of the present invention has sufficient corrosion resistance against preferential corrosion of the welded portion, which is the most problematic when applying the porthole extruded tubing to automotive air conditioner piping.

 Alloy G having the composition shown in Table 4 was formed into a 6-inch outer diameter round bar for extrusion by the DC casting method, and the electrical conductivity of the gunshot after the homogenization treatment was measured. The results are shown in Table 10.

 In the homogenization treatments of the invention examples 1 to 4, after first maintaining at a relatively high temperature, the furnace was cooled to 450 ° C. to 420 ° C. to a temperature at which the most Mn-containing compound was precipitated. Then, the mixture was kept at the same temperature, and then air-cooled to room temperature.

 In Examples 5 to 9 of the present invention, after maintaining at a relatively high temperature, the furnace was cooled to 350 ° C at a cooling rate of 30 ° C / hr, and furnace cooling or air cooling was performed at 350 ° C or less.

In Example 10 of the present invention, at the initial stage, the temperature was maintained at 450 ° C. where precipitation is likely to proceed for 2 hours to precipitate fine precipitates, and then the temperature was raised to 600 ° C. It was carried out with the intention of increasing the diameter of the precipitate by holding the temperature and holding for a short time and then cooling the furnace at 30 ° C / hr.

 In Example 11 of the present invention, the progress of the precipitation was aimed at by maintaining the temperature at around 450 ° C. where the precipitation is most easily performed for a relatively long time.

Of the comparative examples in Table 10, Comparative Examples 5 and 6 were held at a high temperature under the same or similar conditions as the homogenization treatment often used for A1_Mn-based alloys, and 560 in Comparative Example 7. After holding at 3 ° C for 3 hours, both were cooled by water cooling or air cooling at a high cooling rate (> 100 ° C / hr).

Table 10

Item Rate of homogenization condition after homogenization process (IACSX)

6 1 0t: x 4hr + 450 ^o Cx 2 Ohr air cooling

 1 (610 te 450 te: 30 te / hr) 4 1. 1

58 Ot: x 4hr + 450 ° CX 2 Olir air cooling

 2 (580 te 450 te: 30 / hr) 4 1.3

6 1 O'CX 4fir + 420 te x 2 Ofir air cooling

 3 (610 te 450 te: 3 (TC / hr) 41.4 525 te X 2 hr + 450 te X 12 tir air cooling

 4 (525t: -450 ': 30 ° C / hr) 43.7 Departure 55 CC 1 2hr furnace cooling

 5 (550t:-* T: 30 / iir) 42. 0 Description.

 6 (550 ° C-350 ° C: 30r / hr. 35 (TC or less air-cooled) 41.9 Example 550 T: 6 rini ^

 7 (550 ° C-350 ° C: Air cooling below 30 ° C / hr. 350 ° C) 4 1.7

525 x 8 fir furnace cooling

 8 (525 te 350 te: 30 te / hr, air cooling below 350) 42.5

600 ° C X 4 hours furnace cooling

 9 (600 ^ -35013: 30t: / hr. Air cooling below 350) 41.0

4 50T: X 2hr + 6 00 ° C X 2 rip½

 10 (450-600: 50 / hr, Γ> 00Χ: -ΚΤ: 30t: / hr) 4 1.1

4 50 "x 6hr? Ίϊ

 11 46. 2

6 1 0 T X 6hr¾Water ¾】

Ratio 5 (Water-cooling: 鐯 Take the lump out of the furnace and water by the stiffener) 36.8 铰 60 O X 12hr air cooling

 6 37.6 Example

 560 te X 3hrf¾ (water cooled

7 (Water cooling: ^ Lump is taken out of the furnace and water-cooled by a shrinkler) 38. 9 Each extruded billet was cut after homogenization, and hot extruded using a porthole die on a tube of 12.7 mmφX1.2 mmt in three pieces each. In each case, the pellets were extruded by heating the billet to a temperature in the range of 43 to 47 ° C by induction heating. In each case, the characteristics of the extruded tubing were evaluated for the third product. Evaluation samples were taken at six locations at equal intervals from the entire length of the extruded tubing. The conductivity of the collected sample was measured. Table 11 shows the results.

Table 11 shows the measurement results of the front end (No. 1), which has the lowest conductivity, and the rear end (No. 6), which has the highest conductivity, and the difference (Δ Ε 〇) between the two. Was.

Table 11

 Ratio measurement result Material

 Front end rear end side Front and rear end EC g (No. (No. 6) difference ()

510 te X4hr + 450 X20tir2 cold

 1 42. 0 42. 6 0.6

580 X4hr + 450i: x20hr air cooling

(C58O ^< → ^c 0 ^r ^ 30 / hr) 42.2 42.7 0.5

6iO ° CX4hr ÷ 420T; x20hr¾ ^

0 42. 2 42. 5 0. 3 pcs 52S ^< xr + 50t: xi hr ^^

 J 41. 0 41. 0 0. 0

550 ° C XL r Furnace cooling

 1 42. 2 43. 1 0.9 m 550 at Xl2hr

 0, 42. 1 42. 9 0.8

55 (TCx6hr furnace ^

 7

 11 1 41. 6 42. 5 0.9

525 ° C x 8hr furnace cooling

 Q, r 41. 3 42. 31.0

600 times X4hr furnace cooling

 Q 4 1-8 42.5 0.7

45 (TC x Zhr + 600 to 2hr ^ cold

 10 ~ * fi0O ": bo u nr.. Ji} ./nr 41. 7 42. 4 0.7

450 ° CX36hr air cooling

 42. 0 42. 6 0.6

610 * Cx6hr¾Water! ^ Reject

Ratio 5 38. 6 40. 2 1.6 Comparison 600t: x I2hr air cooling

 6 38. 9 40. 8 1. 9 Example

 5i5 (CX3tiriS water cooling

F 39.0 40.8 1.8 According to Table 11, in the present invention example, the conductivity was included in the conductivity of about 41 to 43 IACS%, and the conductivity difference AEC at the front and rear ends was 1 IACS% or less in all cases. This is because precipitation was already progressing in the homogenization stage, and precipitation in the extrusion stage was suppressed.

 On the other hand, in the comparative example, due to precipitation during extrusion, the conductivity tends to increase from the front end side to the rear end side, and the AEC became a value close to 2 IACS% from 1.6 IACS%. .

 Next, Table 12 shows the results of a corrosion resistance test after a CASS test (test time: 200 hr).

At this time, preferential corrosion of the weld was observed and the degree of corrosion was evaluated.

Table 12

tLS: The evaluation of the S diet prior to S In any of the materials, there is no abnormality in the pitting corrosion state in the non-welded portion.

 In the examples of the present invention, the corrosion state of the welded portion was ◎ (no corrosion at the welded portion) or 〇 (slightly pitted pits), indicating extremely excellent corrosion resistance. In 〇, the welded part has a tendency to corrode, but the corrosion progresses slower than the non-welded part, and there is no practical problem.

 On the other hand, in each of the comparative examples, remarkable preferential corrosion of the welded portion occurred, and in particular, a through-hole was formed at the point X.

 As a result, when the homogenization treatment conditions were appropriately adjusted and the difference in the electrical conductivity (precipitation state difference) in the longitudinal direction of the extruded tubing caused by precipitation during extrusion was suppressed to 1 IACS% or less, as in the present invention, It can be seen that the corrosion resistance of the weld can be ensured.

As a result of investigating the mechanical performance, it was found that each of the pipes of Example 1 of the present invention 1 and the pipe of Comparative Example 3 had a tensile strength of 99-: L 08 N / mm ² , 0.2% yield strength 38--4 In the range of 5 mm / πιπι and elongation of 38 to 43%, the same tensile properties as the current material were shown.

 In addition, it was confirmed that both the bending property and the shaft seal bead property (B type shown in FIG. 2 (B)) of the pipe material of the present invention were excellent.

 (Example 10)

Alloys H to P having the compositions shown in Table 4 were formed into a 6-inch outer diameter extruded round bar by DC forming, and the obtained block was homogenized in the same manner as in Example 8. (600 ° C x 4 hr + 450 ° C x 0 hr air cooling: 600 ° C → 450 ° C cooling rate 50 ° (: ^// ] 1]?) Then, the lump is cut into extruded billets, and a 12.7 mm ø1.2 mm t tube (three welded portions) is formed by a porthole extrusion method of two co-extrusions. Extruded. The extruder was heated to a heating temperature of 450 to 480 ° C by induction heating. The extrusion speed was set at 50 m / min as the target speed, or it was impossible to extrude at that speed depending on the material. Table 13

As is evident from Table 13, alloys H to M could be extruded at a predetermined extrusion speed, but alloys N and P had extremely low extrusion speeds of about 5 m / min. At the stage, it was not extrudable, and alloy 0 was not extrudable at all. This is M n or Cu for alloys N and P respectively. Is excessively added, and hot deformation resistance is high. In alloy 0, Mg, which increases deformation resistance most, is added excessively.

 Therefore, these alloys are not suitable for extrusion of relatively thin small-diameter pipes used in automotive air-conditioning piping.

 Next, with respect to the extruded extruded tubing, the electrical conductivity was measured for each longitudinal portion of the extruded tubing. Table 13 shows the values of ΔEC for the front end side (No. 1) and the rear end side (No. 6). The conductivity difference AEC in the longitudinal direction of all materials was 1.0 IACS% or less. I got it.

Tensile properties, corrosion resistance, and workability of materials H to M that can be extruded at a predetermined extrusion speed were investigated. The results are shown in Table 14.

Table 14

 Tensile performance * fi'J corrosion (CASS200I)) Workability (ke, t,) Alloy 1 out W

TSYSE 1 Non-weld welded f weld [1 IJ burring-processing (N / (N / rara ² ) (%) Example of present invention H possible 9 7 3 7 4 0 〇 〇 〇 〇 〇 〇 〇 II 1 1 8 9 9 〇 允 允 允 允 允 允 1 O 1 1 2 44 4 3 〇 〇 O 〇 Invented JK Yes 1 0 2 40 4 1 〇 〇 〇 O

 Slightly rough skin

L Possible 8 9 2 8 4 5 〇 ¾ ¾ ¾ Yes Present example possible 1 1 6 4 4 4 2 〇 〇 〇 O Comparative example N Not possible Comparative example O Not possible Comparative example P Not possible

 9 5 ~

Current material Possible 1 2 5 3 5 or more 30 or more 〇 O 〇

According to Table 14, the tensile properties of each test example of the present invention other than the alloy L (comparative example) were equal to or higher than those of the current pipe material. Since the alloy L has a small amount of Mn, both the tensile strength (TS) and the 0.2% strength (YS) were low.

 The corrosion resistance of each sample in the longitudinal direction of the extruded tubing was evaluated by a 200-hour CAS test. As a result, no particularly problematic corrosion state occurred in the welded and non-welded parts of any of the extruded tubing materials of alloys H to M. In the welds, ΔE C was all lower than 1 IACS%, and in any case, there was no or no problem with preferential corrosion of the welds.

 The bending workability and end workability (shaft seal bead workability: type B in Fig. 2 (B)) were investigated for each piece. Except for alloy L, it could be processed soundly. For Alloy L, rough surface during bending and out-of-dimension during edge processing occurred. This indicates that the tubing is somewhat soft and unsuitable for automotive air conditioning piping.

 As described above, the porthole extruded tubing after subjecting the alloys H to K and M of the present invention to the homogenization treatment of the present invention has the characteristics and workability required for automotive air conditioner piping, and is suitable for automotive air conditioning piping. It is fully applicable.

 On the other hand, the alloys L, N, 0, and P of the comparative examples are not practical because porthole extrusion is impossible or only low-speed extrusion is possible. Industrial applicability

The hollow material of the present invention has no difference in the structure (such as the amount of precipitated Mn) between the welded portion and the non-welded portion in porthole extrusion, preferential corrosion of the welded portion is prevented, and is used as a building material. It is suitable. Hollow of the present invention The method for producing the material is suitable as a method for easily producing the hollow material by subjecting the ingot to a predetermined homogenization treatment to precipitate Mn in a coarse compound. Things.

 Further, the extruded tubing of the present invention is suitable as an aluminum alloy porthole extruded tubing for air conditioning piping in which preferential corrosion of a welded portion is improved. In the method for producing an extruded tube material of the present invention, the extruded tube material is easily produced by subjecting a lump to a predetermined homogenization treatment to coarsely precipitate a compound containing the alloy element Mn. This is a suitable method for performing the above. Although the present invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified, but rather the spirit and scope of the invention as set forth in the appended claims. It should be interpreted broadly without violating the scope.

Claims

Sought 1. An aluminum alloy hollow material manufactured by porthole extruding an aluminum alloy lump containing at least 0.31.5 wt% of Mn, or by performing a lottery process with porthole extrusion. of  11- An aluminum alloy hollow material characterized in that the difference in electrical conductivity in each part in the longitudinal direction is 1.0 IACS% or less.  2. Homogenize aluminum alloy ingot containing at least 0.3 to 1.5 wt% of Mn, and then extrude this ingot through porthole or draw through with porthole extrusion. In the method for producing a material, the homogenization treatment is carried out at a predetermined temperature of 500 to 63 ° C. for 24 hours, and then at a cooling rate of 100 ° C./hr or less. 2. The method for producing a hollow aluminum alloy material according to claim 1, wherein the aluminum alloy hollow material is cooled to a predetermined temperature of 00 ° C. and kept at this temperature for 448 hours. 3. Homogenize aluminum alloy ingot containing at least 0.311 · 5 wt% Mn, and then extrude this ingot through porthole or porthole extrusion and drawing to obtain hollow material. In the method for producing, the homogenization treatment of the mass is maintained at a predetermined temperature (Ti) of 550 ° C for 0.16 hr, and then from the Ti temperature to 100 ° C / hr. Cooling to 350 ° C (T ₂ ) at the following cooling rate: 後 After reaching temperature Τ Time until reaching temperature _{2 is} assumed to be 1048 hr, and at any cooling rate from T ₂ temperature 2. The method for producing a hollow aluminum alloy material according to claim 1, wherein the method is performed by cooling to room temperature. 4. Aluminum containing at least 0.31.5 wt% Mn In a method for producing a hollow material by subjecting an ingot of alloy to homogenization, and then extruding the ingot by porthole, or extruding with porthole and drawing, the homogenization of the ingot is performed by 400 2. The method for producing an aluminum alloy hollow material according to claim 1, wherein the aluminum alloy hollow material is kept at a predetermined temperature of up to 500 ° C. for 12 to 48 hours and then cooled to room temperature.  5. Homogenize aluminum alloy ingot containing at least 0.3 to 1.5 wt% of Mn, and then extrude the ingot through porthole or porthole extrusion and drawing. In the method for producing a hollow material, the homogenization treatment of the lump is maintained at a predetermined temperature of 400 to 500 ° C for 0.5 to 4 hours, and then the temperature is maintained at 550 to 63 ° C. After the temperature is raised to the specified temperature and maintained at that temperature for 0.5 to 4 hours, it is cooled to 350 at a cooling rate of 100 / hr or less, and the room temperature is cooled from 350 ° C at any cooling rate. 2. The method for producing an aluminum alloy hollow material according to claim 1, wherein the aluminum alloy is cooled.  6.Mn 0.8-1.5 wt%, Fe 0.1-0.7 wt%, Sio03-0.6 wt%, CuO. 45 wt%, Mg 0.0-0.3 wt%, Cr 0.0-0.3 wt%, Tio.0-0.l wt% -ZnO.0-0.5 Aluminum alloy containing one or more of wt%, Zr 0.0-0.3 wt%, Ni 0.0-0.3 wt%, and the balance of Al and unavoidable impurities An aluminum alloy extruded tube for air conditioner piping produced by continuous hot extrusion of a lump by a porthole method. The extruded tube has a conductivity of 39.0 IACS% or more, and the extruded tube has a longitudinal section. Aluminum alloy extruded tubing for air conditioner piping characterized in that the difference in conductivity is 1.0 IACS% or less. 7 .Mn 0.8 to 1.5 wt%, Fe 0.1 to 0.7 wt%, Sio. 0.3 to 0.6 wt%, CuO.0.0 to 0.45 wt%, Mg 0.0 to 0.3 wt%, Cr 0.0 to 0.3 wt%, 0 to 0.5 wt% -ZnO.0 to 0.5 wt%, Zr0.0 to 0.3 wt%, Ni0.0 to 0.3 wt% Aluminum alloy containing one or more types and the balance of A1 and inevitable impurities A lump is subjected to homogenization treatment and then extruded into tubing by a porthole continuous hot extrusion method. A method of manufacturing an extruded tubing material, comprising: maintaining the mass of the lumps at a predetermined temperature of 500 to 63 ° C. for 0 to 24 hours, and then cooling the same to 100 ° C./hr or less. A method for producing an aluminum alloy extruded tube for air-conditioning piping, comprising cooling to a predetermined temperature of 400 to 500 ° C. at a speed and maintaining the temperature at this temperature for 4 to 48 hours. 8.Mn 0.8-1.5 wt%, Fe 0.1-0.7 wt%, Sio.0.3-0.6 wt%, CuO.0.0-0 4.5 wt%, Mg 0.0-0.3 wt%, Cr 0.0-0.3 wt%, Tio.0-0.l wt% .ZnO.0-0. Aluminum containing one or more of 5 wt%, Zr 0.0-0.3 wt%, NiO.0.0-0.3 wt%, with the balance being A1 and unavoidable impurities A method for producing an aluminum alloy extruded tube for air conditioner piping in which a homogenized alloy is subjected to a homogenizing treatment and extruded into a tube by a porthole type continuous hot extrusion method. After maintaining at a predetermined temperature (T) of 500-630 ° C for 0-48 hr, 350 ° C (T 2) at a cooling rate of 100 ° C / hr or less from the T temperature air conditioning and cooling, the time up to the arrival after T ₂ temperature T i temperature was 1. 2 to 4 8 hr, characterized that you performed by cooling to room temperature T ₂ temperature at any cooling rate Al for piping A method of manufacturing extruded tubing for minium alloys. 9 .Mn 0.8 to 1.5 wt%, Fe 0.1 to 0.7 wt%, Si 0.03 to 0.6 wt%, CuO.0.0 to 0 4.5 wt%, Mg 0.0-0.3 wt%, Cr 0.0-0.3 wt%, Ti 0.0-0.1 wt% .ZnO. Aluminum alloy containing one or more of 5 wt%, ZrO.0-0.3 wt%, Ni0.0-0.3 wt%, and the balance Al and unavoidable impurities. A method for producing an aluminum alloy extruded pipe for air conditioner piping in which a lump is subjected to a homogenization treatment and extruded into a pipe by a porthole type continuous hot extrusion method, wherein the homogenization treatment of the lump is performed by 40%. A method for producing an aluminum alloy extruded tubing for air conditioner piping, wherein the extruded aluminum alloy is maintained at a predetermined temperature of 0 to 500 hrs for 12 to 48 hours and then cooled to room temperature.  8 to 1.5 wt%, FeO. 1 to 0.7 wt%, Si0.03 to 0.6 wt%, CuO. 0.45 wt%, Mg 0.0-0.3 wt%, Cr 0.0-0.3 wt%, TiO.0-0.l wt%, ZnO.0-0 .5 wt%, ZrO.0-0.3 wt%, Ni0.0-0.3 wt%, containing one or more of them, with the balance being A1 and unavoidable impurities This is a method for manufacturing aluminum alloy extruded tubing for air-conditioning piping by extruding aluminum alloy lumps into tubing by a port-hole continuous hot extrusion method. After maintaining at a predetermined temperature of 400 to 500 ° C for 0.5 to 4 hours, the temperature is raised to a predetermined temperature of 550 to 63 ° C, and the temperature is increased to 0.5 to 4 hours. After being held, it is cooled to 350 ° C at a cooling rate of 100 ° C / hr or less, and then cooled from 350 ° C to room temperature at an optional cooling rate. For Method for producing a Miniumu alloy extruded tube material,