KR20100133734A - Heat treatment method of abrasion resistant corrosion resistant alloy steel long shaft member and apparatus therefor - Google Patents

Abstract

 Provided is a simple heat treatment method and apparatus for preventing deformation such as bending of abrasion-resistant corrosion resistant alloy steel long shaft member having air-quenchability, which is extremely difficult to bend after heat treatment.

 In the heat treatment method with quenching and tempering operation of the wear-resistant corrosion resistant alloy steel long axis member having an air quenching resistance of Ø18 mm or more, the quenching process involves inserting the long axis member into the pipe jig and placing the pipe jig into the rotary furnace accessory furnace. In the state that the above-mentioned long-axis member ascends below 90 degrees from the lower surface along the pipe jig inner wall and then slides to the lower surface in a state where it is inserted and maintained horizontally, and rotates it while maintaining the heat while rotating horizontally. It is characterized by having a process of air cooling while.

Description

 Heat treatment method and equipment of shaft material with wear resistance, corrosion resistance alloy}

  The present invention relates to a heat treatment including a bending correcting action of a wear resistant corrosion resistant alloy steel long shaft member having air-cooled quenchability, which is difficult to bend correction after heat treatment, particularly in connection with a manufacturing process of a long axis mechanical component such as a wear resistant corrosion resistant alloy steel screw for a plastic extruder / injector. A method and apparatus therefor

 Recent members requiring high hardness before and after HRC60 due to the need for strength / abrasion resistance in long-shaft parts with easy bending properties, such as heat treatment during the manufacturing process of mechanical parts made of special steel with air hardenability, especially screws in plastic extruders / injectors. Since heat treatment such as quenching and tempering is difficult to process a thread after heat treatment, the thread part is widely used in that it is easy to process and advantageous in terms of cost. .

 However, it is very difficult to bend or bend correction in special steels, especially alloy tool steels, among them, KS STD materials and modified steel types. In addition, many bending accidents of the long axis occur in the bending work.

 Conventionally, the bending correction for easily bent products of such hardened quenched long axis members is generally performed at the tempering operation temperature or the temperature before or after the following methods (Existing Example 1) and (Existing Example 2). It has been tempted and enforced.

  (Existing Example 1) How to Use Pit

  As shown in Fig. 3, the long axis member is restrained by the bending correction jig and pulled into the Pit for each jig to be heated / maintained / slowly cooled, and then the bending is corrected several times by comparing it with the target value of the straightness of the long axis member. How to.

  (Existing Example 2) Calibration by Heat Treatment

  The principle of heat treatment utilizes the fact that plastic deformation is significantly promoted when the microstructure changes or changes in precipitation during tempering of the quenching material.

The actual calibration is to press the bent portion by pressing while heating / maintaining the entire part or the bent portion by induction heating, burner heating, etc., as shown in FIG.

 (Existing Example 1) and (Existing Example 2) above have the following problems.

  (Existing Example 1)

(1) This method requires expensive Pit furnace, and it is very expensive because heating / cooling operation operation is repeated several times.

(2) Since the restraining jig may be a jig for correcting the bending deformation and at the same time it may be a standard for checking the amount of bending, the jig should be prepared according to the size according to each major axis, and correction processing is required to maintain the straightness. Additional costs / maintenance costs are high.

(3) In the current example of the calibration of semi-finished screw material of about Ø20 ~ Ø150mm (500L ~ 3000L), even if 3 ~ 5 times of calibration work is performed, the resultant bending amount is about 0.3 ~ 1.0mm (per 1000mm length). The work efficiency drops considerably and the degree after calibration is not so good.

 (Existing Example 2)

(1) In this method, since the part compressing the press corresponds to the local part which starts cooling after heating, a local heterogeneity of the microstructure occurs, thus increasing the frequency of fracture accidents.

(2) It requires a high level of function and experience, and it is cumbersome because it corrects the overall bend while modifying a lot of the complex bending properties of the entire long axis.

In order to bend and correct a large number of workpieces, the facility is complicated and there are many practical problems.

 SUMMARY OF THE INVENTION An object of the present invention is to provide a simple heat treatment method and apparatus for preventing deformation such as bending of an anti-corrosion alloy steel long axis member having air-cooled hardenability which is very difficult to bend after heat treatment in order to solve the above problems. have

 In order to solve the above problems and achieve the object, the present invention uses the following method.

(1) In the heat treatment method of the present invention, in the heat treatment method including the step of quenching and tempering the wear-resistant corrosion resistant alloy steel long axis member having air-cooled quenchability of an outer diameter of Ø18 mm or more, The process of charging and the pipe jig loaded with the long shaft member are mounted in the rotary furnace heating furnace and heated and maintained while rotating in a horizontal state.The pipe jig with the heated and retained long shaft member loaded is removed from the heating furnace. After moving to the rotary device installed separately, it is a heat treatment method of the wear-resistant corrosion-resistant alloy steel long-axis member characterized in that it is subjected to a step of air-cooling separately while rotating in a horizontally maintained state.

(2) In the heat treatment method of the present invention, when the pipe jig loaded with the long axis member described above is rotated, the long axis member charged in the pipe jig rises below 90 degrees from the bottom along the pipe jig inner wall, and then slides downward. It rotates as if repeated, It is a heat processing method of the wear-resistant corrosion resistant alloy steel long-axis member as described in said (1).

(3) The heat treatment method of the present invention is characterized in that the pipe jig described above corresponds to an inner diameter of 1.2 to 5 times the outer diameter of the above-mentioned long axis member, and its straightness is within 1 mm per 1000 mm in length. It is a heat treatment method of the wear-resistant corrosion resistant alloy steel long-axis member described in (1) or (2).

(4) The heat treatment method of the present invention is described in any one of (1) to (3) above, wherein the pipe jig is formed of a heat resistant steel material and is equipped with an axial stopper that prevents the pipe jig from slipping out of the pipe jig of the long axis member. It is a heat treatment method of a wear resistant corrosion resistant alloy steel long shaft member.

(5) The heat treatment method of the present invention is characterized in that the straightness of the long-axis member after the above-described tempering operation step is within 0.1 mm per 1000 mm in length. It is the heat treatment method of wear-resistant alloy steel long shaft member.

(6) The heat treatment apparatus of the present invention has a pipe jig loaded with a wear-resistant corrosion resistant alloy steel long axis member, a heating furnace to which the pipe jig is mounted to maintain the pipe jig horizontally, and a pipe jig mounted in the furnace horizontally. Wear-resistant corrosion-resistant alloy steel long axis with a rotating drive control method for driving the rotating device in such a way that the rotating device rotated in the maintained state and the above-mentioned long axis member charged in the pipe jig rise and slide along the inner wall of the pipe jig. It is a heat treatment apparatus of a member.

(7) The heat treatment apparatus of the present invention is characterized in that the above-mentioned rotary drive method drives the rotating apparatus as the above-mentioned long axis member repeats the operation of sliding down to the lower surface after the above-mentioned long axis member rises below 90 degrees from the lower surface along the inner wall of the pipe jig. It is a heat treatment apparatus of the wear-resistant corrosion resistant alloy steel long-axis member described in 6).

 According to the present invention as described above, by specifying the heat treatment conditions, it is possible to prevent deformation such as bending of the wear-resistant corrosion resistant alloy steel long axis member having air-cooled hardenability, which is very difficult to bend correction after heat treatment through a simple heat treatment method and a heat treatment apparatus.

 Therefore, by using the method and apparatus of the present invention, an expensive facility or a heat treatment method such as a Pit furnace of a deformation correction process, which was previously required in the post-heat treatment process of a long-axis mechanical component such as a wear-resistant corrosion-resistant alloy steel screw for a plastic extruder / injector Since the calibration is unnecessary due to the compression of the back and the like, the manufacturing cost is reduced, and the industrial value is high, such as preventing quality loss caused by the calibration after heat treatment and improving the quality.

 According to the present invention, numerous studies have been conducted to solve the above problems. As a result, in order to prevent deformation such as bending during heat treatment of abrasion-resistant alloy steel long-axis member having air-cooled quenching resistance, the long-axis member processed to a predetermined shape is mounted on a pipe. It was found that it was effective to perform heat treatment such as quenching / tempering while rotating in the inserted state.

 Based on these findings, the present invention inserts an abrasion-resistant corrosion resistant alloy steel long shaft member having an air-quenching quenchability processed into a predetermined shape into a rotary device heating furnace in a state in which it is inserted into a heat-resistant steel pipe jig defining internal diameter and straightness. As long as the long-axis member inserted in the pipe jig rises up to an angle of 90 degrees or less from the bottom surface of the pipe jig while it is kept horizontal, it rotates and heats / cools while rotating by using the rotation drive control method as if the sliding motion is repeated. The present invention has been completed by discovering a simple heat treatment method and apparatus for preventing deformation of the long axis member such as bending.

 That is, according to the present invention, the shape of the charging jig of the long-axis member and the heat treatment conditions are limited to the following ranges, thereby preventing the deformation of the wear-resistant alloy steel long-axis member having air-cooled hardenability, which is difficult to bend correction after heat treatment, and the like. It is possible to provide a heat treatment method and apparatus therefor.

 The following is a description of the reason for limiting the shape of the charging jig of the long-axis member of the present invention and the reason for limiting the heat treatment conditions.

   (1) The shape of the charging jig of the long shaft member

 The heat-resistant steel pipe jig (long-axis member insertion jig) in which the long-axis member of the present invention is charged has an inner diameter of 1.2 to 5 times the outer diameter of the long-axis member, and its straightness is less than 1 mm per 1000 mm in length. The axial stopper which prevents slipping out of the pipe jig of a member is attached.

 By using the heat-resistant forced pipe jig having the inner diameter and the straightness described above, it is possible to prevent deformation such as bending of the long-axis member by operating for the purpose of corrective action in the heat treatment described later.

 That is, when the long-axis member is charged during the heat treatment and rotated by the pipe jig, the long-axis member is repeated along the pipe jig inner wall and then slides downward to prevent deformation such as bending during the heat treatment of the long-axis member. have.

 In the case of the charging jig material, it is possible to use both the general heat-resistant steel (high chromium (Cr) -containing ferritic heat-resistant stainless steel, etc.) or the general pipe, and the steel component is not specifically defined.

 In the case of the long axis member material, all of the chromium (Cr) -molybdenum (Mo) steels (for example, KS D 3753 alloy tool steels such as STD1, STD11, STD61, etc.) having air-quenching quenchability, which are used as general alloy tool steels, are all used. It is possible. The steel component is not particularly limited, but in order to obtain desired strength after wear resistance, corrosion resistance and heat treatment, it is preferable to use steel adjusted to the following component composition ranges.

 Carbon (C): 0.1-1.3%, Silicon (Si): 0.5% or less, Manganese (Mn): 0.6-1.2%, Chromium (Cr): 0.5-1.8%, Molybdenum (Mo): 0.6-3.5%, Vanadium (V): 0.2-1.2%, phosphorus (P): 0.04% or less, sulfur (S): 0.03% or less, nickel (Ni): 0.6-2.2% and metal member containing residual amount of iron (Fe)

 By using a heat-resistant steel pipe jig having the following shape it is possible to provide a wear-resistant corrosion-resistant alloy steel long axis member that can obtain the desired hardness and straightness through air-cooled quenching.

 The long axis member having such a property can be manufactured by the following heat treatment method.

(2) Heat treatment step of the long shaft member

(Heat treatment method)

 A long axis member having an air diameter quenchability of Ø18 mm or more processed into a predetermined shape is charged into a heat-resistant steel pipe jig having an inner diameter and a straightness of the above (1), and the respective pipe jig is inserted into the rotary device part heating furnace. This rotating apparatus is equipped with two motor-driven turning rollers (rotary rollers) as shown in FIG. 1, for example, and is mounted on these two rollers in a state where the long shaft member is loaded in a jig and kept horizontal.

 Next, as shown in Fig. 1, the rotational drive control method for driving the above-described rotating device such that the long-axis member charged in the pipe jig rises below 90 degrees from the bottom along the pipe jig inner wall and then slides down to the bottom. For example, it is heated and maintained while rotating using a motor drive controller or the like.

 Thereafter, the pipe jig is removed from the heating furnace and moved to a separate rotary device (for example, a device having two motor-driven turning rollers) as shown in FIG. After quenching while rotating to quench.

 Subsequently, the pipe jig into which the long-axis member quenched by air cooling was put into the above-mentioned rotary apparatus attached heating furnace once again, and is heated and maintained while rotating in the state maintained horizontally like quenching.

 Thereafter, the pipe jig loaded with the heated and held long shaft member is taken out of the heating furnace and moved to the above-described rotating apparatus installed separately.

   a. Heating temperature and holding time of the quenching process

   In order to obtain a desired heat treatment hardness (HRC: 50-65) according to the air cooling quenching, it is preferable to heat the long-axis member at 1000 to 1050 캜 for 30 to 360 minutes.

 When the heating temperature exceeds 1050 ° C., the crystal grains become large and sufficient hardness cannot be obtained, and the toughness deteriorates and easily bends or breaks. On the other hand, if it is less than 1000 degreeC, a hardening effect cannot be acquired by austenitization and the lack of carbide solid solution.

 In addition, when the holding time is less than 30 minutes, carbides are not sufficiently dissolved so that the desired hardness cannot be obtained. The upper limit of the holding time is 240 minutes so as not to impair productivity.

   b. Pipe jig rotation operation of heating and holding process (quenching process)

   When the long-axis member is inserted into the pipe jig and rotated in a horizontal state for the purpose of a corrective action during heat treatment, the long-axis member slides to the bottom surface after rising up to 90 degrees or less from the bottom along the inner wall of the pipe jig as shown in FIG. Rotate the falling motion repeatedly. If the ascending angle exceeds 90 degrees, the long axis member may fall out of the pipe inner wall and the machining shape may change, so the upper limit is 90 degrees.

 By repeating such an operation, heat treatment (heating and holding) is performed to perform deformation correction action such as bending of the long axis member during heat treatment, thereby preventing deformation.

   c. Cooling Rate and Cooling Stop Temperature in Quenching Process

   In this invention, since the long-axis member which has air-cooled hardenability is used, the cooling rate after heat-and-hold is good as long as it does not impair productivity, and it shall be 15 degree-C / min or more which is more than an air-cooling rate as much as possible. At this time, in order to improve productivity, air may be forced into the furnace by spraying air into the furnace using a nozzle or a fan to adjust the cooling rate.

   Cooling stop temperature shall be 50 degrees C or less as much as possible. This is to secure the desired hardness as unmodified austenite after heating and maintenance as hard martensite. When the cooling stop temperature exceeds 50 ° C., the martensite transformation does not proceed sufficiently, so that the desired hardness cannot be secured.

   d. Pipe jig rotation operation of cooling process (quenching process)

   It carries out similarly to the pipe jig rotation operation of the heating and holding process mentioned above, and stops rotation at cooling stop temperature 50 degrees C or less as much as possible, and then removes a long-axis member from a pipe jig.

   e. Heating temperature and holding time of tempering operation process

   It is preferable to heat a long-axis member to 150-650 degreeC, and to hold for 15 to 360 minutes. This is because toughness and ductility can be improved by tempering the martensite in the transformation state.

 If the tempering operation temperature is lower than 150 ° C., the toughness cannot be sufficiently recovered. If the tempering operation temperature is higher than 650 ° C., some ferrite-> austenite transformation occurs and the toughness cannot be recovered.

 If the holding time is less than 10 minutes, the toughness cannot be sufficiently recovered. The upper limit of the holding time is 360 minutes so as not to impair productivity.

  f. Pipe jig rotation operation of heating and holding process (tempering operation process)

   Same as the reason for limiting the above quenching process.

  e. Pipe jig rotation operation of cooling process (tempering operation process)

   Same as the reason for limiting the above quenching process.

 The heat treatment as described above prevents deformation such as bending of the wear-resistant corrosion resistant alloy steel long-axis component having air-quenchability, which is very difficult to bend after heat-treatment, thereby improving the straightness of the long-axis member after the tempering operation process: 0.1 mm per 1000 mm. It can be suppressed within.

 And in the case of a tempering operation process, you may abbreviate | omit the said rotation operation for the purpose of corrective action, and may perform general tempering operation process.

 Moreover, when annealing is performed as needed, such as internal stress removal and crystal structure adjustment, it is good to adjust cooling rate after heat holding and to cool slowly (for example, furnace cooling etc.). Also in this case, the desired straightness can be obtained by rotating the same as in the above heat treatment method.

 The following is an embodiment of the present invention, which demonstrates the effect of the present invention.

Chemical composition of the wear-resistant, corrosion-resistant alloy steel screw member (about 80% finished semi-finished product) for plastic extruders / injectors, dimensions, materials, straightness, D / d (d: screw outer diameter, D: pipe jig inner diameter) and heat treatment conditions were changed to quench / temper heat treatment of the screw member to prepare a long-axis member (A, B: invention steel, C ~ 0.45: comparative steel ). Table 3 summarizes the results of the presence or absence of surface defects (scratches, cracks, etc.), Rockwell hardness (by HRC, KS B 5526), and straightness (deformation dimensions per 1000 mm length) of the long-axis member.

 When the heat treatment conditions of the present invention are used as shown in the present invention steels A and B of Table 3, there are no surface defects, and a hardness of 50 to 54 can be obtained in HRC, and the length is reduced to a straightness within 0.1 mm per 1000 mm. Can be obtained.

 On the other hand, all of the comparative steels C to 0.45 that did not meet the heat treatment conditions of the present invention did not satisfy desired characteristics in surface defects, strength, and straightness.

River
No. Chemical composition (% by weight) Remarks C Si Mn Cr Mo W V P S A 0.39 5.21 1.38 1.1 STD61 B 0.52 0.88 0.91 0.41 SKT4 C 0.40 0.72 1.12 0.22 SM45C

River
NO. screw Pipe fuzz Remarks Dimension (mm) Dimension (mm) material Straightness (mm) D / d A
B
C Outer Diameter: 50X Total Length 1250L Inner diameter Ø200 × thickness 2t × full length 1500L STS304 4.0
Inventive Example
Inventive Example
Comparative example

River
No. Quenching condition Tempering operation condition Surface defect Hardness (HRC)
Straightness (mm) Remarks Heating temperature
(℃)
Retention time
(minute)
Cooling rate
(° C / min)
Cooling stop
Temperature
(℃)
Rotating operation Heating temperature
(℃)
Retention time
(minute)
Cooling rate
(° C / min)
Cooling stop
Temperature
(℃)
Rotating operation heating Cooling heating Cooling A 1040 60 16.5 50 U U 500 180 7.5 50 U U radish 54 0.008 Inventive Example B radish 0.016 Inventive Example C ^{＊ ＊} radish radish 0.3 ^＊ Comparative example ^＊

Note) * indicates that it is excluded from the scope of the present invention.

 1 is an explanatory diagram of a heat treatment method (heating and holding step) according to an embodiment of the present invention.

 2 is an explanatory diagram of a heat treatment method (cooling step) according to the embodiment of the present invention.

 3 is an explanatory diagram of a bending correction method using a conventional Pit furnace.

 4 is an explanatory diagram of a bending correction method by a conventional heat treatment method.

 5 is an explanatory diagram of the steel shaft member and the jig device;

 6 is an explanatory view of the heat treatment of the steel shaft member.

Claims (7)

 In the heat treatment method of quenching and tempering the wear-resistant corrosion resistant alloy steel long axis member having an outer diameter of Ø18 mm or more, at least the above-mentioned quenching process is performed by inserting the long axis member into the pipe jig and the pipe jig loaded with the long axis member. The process of heating and holding while rotating in the rotating furnace attached to the rotary device and maintaining it horizontally, and the pipe jig loaded with the heated and retained long shaft member are removed from the heating furnace and moved to a separately installed rotary device, and maintained horizontally. A heat treatment method for a wear-resistant corrosion resistant alloy steel long shaft member, characterized by comprising a step of air cooling while rotating in a state.  When rotating the pipe jig loaded with the above-mentioned long-axis member, the long-axis member charged in the pipe jig is rotated as it repeats the sliding motion to the lower surface after rising below 90 degrees from the lower surface along the inner wall of the pipe jig. The heat treatment method of the wear-resistant corrosion resistant alloy steel long shaft member according to claim 1.  The pipe jig mentioned above has an inner diameter of 1.2 to 5 times the outer diameter of the above-mentioned long shaft member, and its straightness is within 1 mm per 1000 mm in length, and the wear resistant corrosion resistant alloy steel described in claim 1 or 2 above. Heat treatment method of a long axis member.  The aforementioned pipe jig is formed of a heat resistant steel material and has a axial stopper which prevents slipping out of the pipe jig of the long axis member. The heat treatment method of the wear-resistant corrosion resistant alloy steel long axis member according to any one of claims 1 to 3.  A method for heat treatment of the wear-resistant corrosion resistant alloy steel long axis member according to any one of claims 1 to 4, wherein the straightness of the long axis member after the aforementioned tempering operation step is within 0.1 mm per 1000 mm in length.  After the pipe jig loaded with the wear-resistant corrosion resistant alloy steel long axis member and the pipe jig equipped with the rotating device rotated while the pipe jig is kept horizontal and the above-mentioned long axis member loaded in the pipe jig are raised along the inner wall of the pipe jig, Heat treatment apparatus of wear-resistant corrosion-resistant alloy steel long shaft member with a rotation drive control method for driving the rotating device as if the sliding motion is repeated.  The above-mentioned rotation drive method is characterized in that the wear-resistant corrosion resistant alloy steel long-axis member according to claim 6, which drives the rotating device as described above, repeats an operation in which the long-axis member rises below 90 degrees from the bottom along the pipe jig inner wall and then slides down to the bottom. Heat treatment device.

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