CN116426818B - A fast spheroidized medium carbon steel bar and its manufacturing method - Google Patents
A fast spheroidized medium carbon steel bar and its manufacturing method Download PDFInfo
- Publication number
- CN116426818B CN116426818B CN202310241369.0A CN202310241369A CN116426818B CN 116426818 B CN116426818 B CN 116426818B CN 202310241369 A CN202310241369 A CN 202310241369A CN 116426818 B CN116426818 B CN 116426818B
- Authority
- CN
- China
- Prior art keywords
- steel
- less
- equal
- rolling
- temperature
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
- C21D1/32—Soft annealing, e.g. spheroidising
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/06—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
- C21D8/065—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires of ferrous alloys
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/04—Making ferrous alloys by melting
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/003—Cementite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/004—Dispersions; Precipitations
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D2211/00—Microstructure comprising significant phases
- C21D2211/005—Ferrite
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Heat Treatment Of Steel (AREA)
Abstract
The invention relates to a quick spheroidizing medium carbon rod steel and a manufacturing method thereof, wherein the steel comprises, by mass, 0.30-0.60% of C, less than or equal to 0.40% of Si, 0.50-0.90% of Mn, less than or equal to 0.020% of P, less than or equal to 0.030% of S, less than or equal to 0.30% of Cr, less than or equal to 0.25% of Cu and Ni, micro-alloy elements such as B can be added for adjusting performance, one or more refined grain elements such as Al, nb and N can be added for ensuring grain size, and the balance is Fe and unavoidable impurity elements. The steel is subjected to smelting, continuous casting, heating, ultralow-temperature rolling and rapid spheroidization, the total spheroidization time is 5.5-6.5 h, and the total spheroidization time is equivalent to softening annealing and is far lower than that of the traditional spheroidization annealing process. The obtained material structure is punctiform spheroidized body, ferrite and a small amount of lamellar cementite. The hardness is less than or equal to 160HBW, the elongation is more than or equal to 30 percent, the upsetting rate is 80 percent, and the cold forging has no cracking, thereby being beneficial to cold forming processing with large deformation. Realize the environment-friendly and high-quality production with high modernization precision, energy conservation and emission reduction.
Description
Technical Field
The invention belongs to the field of special steel smelting, and particularly relates to a high-toughness mine disc saw blade steel plate and a manufacturing method thereof.
Background
The steel part processing technology is gradually changed day by day, and the cold forming processing technology gradually replaces the original hot forming technology so as to improve the surface quality and the dimensional accuracy of the forging piece, improve the yield, reduce the subsequent turning and grinding processing amount, reduce the production energy consumption, reduce the emission, reduce the production cost and the like. Taking automobile parts as an example, the proportion of cold forming is over 20%, and the trend is to increase year by year.
The plastic deformation capability of the steel is poor in a cold state compared with that of the steel in a hot state austenitizing state, and the steel is usually required to be subjected to heat treatments such as rolling control and cooling control, off-line softening annealing, spheroidizing annealing and the like during production, so that the hardness of the material is reduced, and the cold deformability is improved. The general rule is that the higher the content of alloy elements mainly containing carbon is, the higher the hardness and the poorer the plasticity and cold forging performance of the steel are. Taking carbon steel as an example, when the carbon content is less than 0.2%, the hot rolled steel has better plasticity, can be directly subjected to cold forming with smaller deformation, and can be subjected to cold forming with larger deformation and more complexity if the steel is subjected to spheroidization, and the plasticity is obviously improved. However, the low-carbon steel has lower strength, is limited in application, and has obviously improved strength along with the increase of carbon content, and is widely applied to industry, for example, 45 steel.
The 45 hot-rolled steel bar is suitable for cold forming of parts with small deformation such as shafts and the like due to higher pearlite content proportion and lower plasticity, and the 45 steel bar is suitable for cold forming after heat treatment along with the complex parts and the increase of the deformation. A typical heat treatment process is to perform off-line softening annealing (5-6 hours) on cold-processed parts with small deformation after hot rolling, and to perform off-line spheroidizing annealing (usually 12-24 hours) on steel materials to improve the plasticity of the steel materials after the deformation is increased, otherwise, cold forming cracks are easy to generate. Although the conventional heat treatment before cold forming can effectively solve the problem of cold forming cracks, the heat treatment time is longer, the energy consumption is higher, and the method is not suitable for modern green and double-carbon modern manufacture.
In conclusion, the invention is suitable for large-deformation cold forming processing and can rapidly spheroidize the medium carbon steel bar, so that the processing period is shortened, the processing flow is simplified, the production efficiency is improved, the production cost is reduced, the energy consumption is saved, the emission is reduced, and the invention has great economic and social values.
Disclosure of Invention
The invention aims to solve the technical problem of providing a manufacturing method of a medium carbon steel bar which is applicable to large-deformation cold forming processing and can be rapidly spheroidized, and the medium carbon steel bar manufactured by the method has the advantages of good plasticity, applicability to large-deformation cold forming processing, short processing time, consumption reduction and emission reduction.
The technical scheme adopted by the invention for solving the problems is that the quick spheroidizing medium carbon steel bar is represented by 45 steel, wherein the series of steel comprises, by mass, 0.30-0.60% of C, less than or equal to 0.40% of Si, 0.50-0.90% of Mn, less than or equal to 0.020% of P, less than or equal to 0.030% of S, less than or equal to 0.030% of Cr, and the balance of Fe and unavoidable impurity elements.
The residual elements Cu and Ni of the material designed by the invention are usually less than or equal to 0.25%, microalloying elements such as B, ti and the like can be properly added for adjusting the performance, and one or more refined grain elements such as Al, nb, N and the like can be added for preventing abnormal growth of grains in subsequent heat treatment of the part.
The mechanical property of the steel material meets the requirement that in order to be suitable for cold forming processing with large deformation, the plasticity of the material at normal temperature is a key index, the cold upsetting rate without cracking is generally represented by the cold upsetting rate without cracking, the limit upsetting rate without cracking is more than or equal to 80 percent, namely, the material has no cold upsetting cracking phenomenon when the cold upsetting rate is 80 percent. The elongation rate of the steel is more than 30 percent, and the reference hardness of the steel is less than or equal to 160HB.
The core method of the quick spheroidizing medium carbon steel bar is that cementite of a pearlite sheet of rolled steel is broken by ultralow-temperature rolling, a large amount of dislocation energy distortion energy is arranged in the rolled steel, the rolled steel is quickly put into a furnace for quick spheroidizing after being cut off, the total spheroidizing time is about 6 hours, and the total spheroidizing time is equivalent to that of common softening annealing and is far lower than that of the traditional spheroidizing annealing method. The steel material has good cold formability, and has no cracking when the cold heading rate is 80 percent. The steel has a structure of point spheroidized body and ferrite or point spheroidized body and ferrite and a small amount of sheet cementite (the sheet cementite accounts for less than 10% of the total cementite and is distributed in a dispersion shape).
The design principle of each main element of the steel of the invention is as follows:
0.30-0.60% of C. The steel grade of the invention is essentially medium carbon series steel, and the C content mainly determines the proportion of cementite phase in the material, thereby affecting the strength of the material. The lower the cementite phase ratio is, the material strength is not ensured, and the higher the C content is, the higher the cementite phase ratio is, so that the cold formability and the toughness of the steel are reduced. The content of C in the steel material is set to be 0.30-0.60%.
Si is less than or equal to 0.40 percent. Si is usually solid-dissolved in ferrite, and can play a solid-solution strengthening role, remarkably improve the strength of ferrite, but at the same time, reduce the plasticity and toughness of ferrite, and Si element can promote the segregation of some impurity elements and embrittle grain boundaries. Si is added to steel as a common deoxidizing element during smelting. The steel material of the present invention is suitable for cold forming, and in view of the above characteristics, the Si lower limit is set to 0.40% or less, more preferably 0.25% or less.
Mn is 0.50-0.90%. Mn is also one of common deoxidizing elements, is one of the most effective and economical elements for coordinating the strength of the steel, and a proper amount of Mn can obviously improve the strength of the steel without obviously affecting the plasticity of the steel. When S is contained in the steel, mn and S form MnS with good plasticity, and the cutting performance of the steel is improved. The Mn content of the steel is set to be 0.50-0.90%.
P is less than or equal to 0.020 percent. In addition to certain special purpose steel grades P being added as alloying elements to the steel, the general steel grades P are typically detrimental elements which increase the brittleness of the steel. In terms of performance, the lower the P content in the steel material of the present invention is, the better the requirements are, but the more stringent the requirements are, the smelting cost of the steel material is increased, and in summary, the P content of the steel material of the present invention is set to be less than or equal to 0.020%.
S is less than or equal to 0.030 percent. The S element can improve the cutting performance of the steel, when the S content in the steel is proper and Mn generates MnS with good deformability, no obvious influence is caused on the cold formability of the steel, and when the S content is too high and the strip-shaped MnS in the steel is too much along with the rolling deformation of the steel, the variability of the steel can be caused, and the transverse performance of the steel is reduced. The S content range of the steel is set to be less than or equal to 0.030 percent.
Cr is less than or equal to 0.30 percent. Cr is also one of the elements effective and economical in coordinating the strength of the steel, but the steel of the present invention is a medium carbon series steel. Cr is increased, the structure transformation curve of the steel is obviously affected, the performance of the steel is transformed, and the spheroidization principle and method are changed. The Cr content of the steel is set to be less than or equal to 0.30 percent.
The residual elements Cu and Ni of the material designed by the invention are generally less than or equal to 0.25%, microalloying elements such as B and the like can be properly added for adjusting the performance, and one or more grain refining elements such as Al, nb, ti, N and the like can be added for preventing abnormal growth of grains in subsequent heat treatment of the part.
The invention relates to a medium carbon series steel. After the chemical components are controlled, innovative process control is needed in the subsequent rolling and heat treatment processes, so that the aim of no cracking during large-deformation cold-formability processing is fulfilled, the surface quality and the dimensional accuracy of the cold-formed part are finally improved, the turning or grinding quantity of the part is reduced, the yield is improved, the heat treatment before forming is omitted, and the like.
The invention also aims to provide a manufacturing method of the quick spheroidizing medium carbon rod steel, which is also a key control point of the steel, and mainly comprises the following specific procedures:
smelting, continuous casting, heating rolling and rapid spheroidizing
The chemical components, especially P, of the series of steel types need to be controlled during smelting, when the converter or the electric furnace is used for smelting, slag needs to be produced quickly, the fluidity of the slag is increased, meanwhile, the temperature in the furnace is controlled to be less than or equal to 1670 ℃, and the temperature is too high to be unfavorable for dephosphorization, because the dephosphorization process is not carried out in the steel production flow from tapping. Once the phosphorus exceeds the control target, it cannot be saved. Meanwhile, the purity of molten steel needs to be controlled, and large-particle inclusions in the steel, especially large-particle inclusions on the surface and under the skin, are easy to crack during cold heading.
The purity of steel is further controlled during continuous casting, the fluctuation of the liquid level is controlled to be less than or equal to +/-5 mm by means of on-line automatic monitoring of the liquid level of a crystallizer, and once the liquid level fluctuates, covering slag is easily involved in the phenomenon that the covering slag is caught by a blank shell to produce subcutaneous inclusions. The superheat degree is controlled at the middle lower limit, the target temperature is 10-25 ℃, the cooling water quantity of the crystallizer is controlled at the middle upper limit, and the high-strength cooling of the primary green shell is ensured at the two points, so that the thickness of the reinforced equiaxed fine crystal structure is increased, the surface quality of a casting blank and a subsequent rolled material is increased, the occurrence of surface microcracks is reduced, and the microcrack expansion during cold forming is avoided.
Rolling after continuous casting is one of the core processes of the present invention. Realize ultralow temperature rolling, make cementite fracture of rolling steel pearlite lamellar, increase the distortion energy of rolling the inside of steel of lower line, be favorable to cementite fast fracture, dissolution and spheroidization to separate out during the follow-up spheroidization.
The casting blank is heated in a step-by-step heating furnace, the temperature of a preheating section is 650-750 ℃, the temperature of a heating section is 850-950 ℃, the temperature of soaking forging is 950-1020 ℃, and the total heating time is more than or equal to 180min in order to ensure that the components of the blank are heated uniformly. In the heating process, soaking forging temperature control is very important, the steel is rolled at ultralow temperature, the temperature of a soaking section is as low as possible in the rolling capacity range, if the heating temperature is high, the surface temperature of the steel can be reduced in a limited way through subsequent rolling control and cooling control, but the core temperature of the steel is difficult to control, and particularly when the rolling specification is more than or equal to phi 60mm, the technical problem of uneven temperature of the controlled rolling and cooling section is more difficult to solve. And (3) after the billet is discharged from the heating furnace, performing high-pressure water descaling, wherein the initial rolling temperature after descaling is 880-950 ℃. And then adopting 25 tandem rolling units to carry out tandem rolling, wherein the 25 rolling machines are respectively 6 roughing machines, 10 middle rolling machines, 4 pre-finishing machines and 5 finishing machines. The middle rolling mill, the pre-finishing mill and the finishing mill group are all provided with water passing through the water passing tank for water cooling, so that the rolling and cooling control can be realized. During controlled rolling and cooling, the total process design thought is that more distortion energy is stored in the rolling process of steel, so that cementite is easier to fuse in the subsequent spheroidization. And (3) carrying out controlled cooling by sequentially arranging at least four sections of spray water tanks during and after rolling, carrying out spray cooling by distributing No.1 water tanks after the rolling, distributing No.2 and No. 3 water tanks after the pre-finish rolling, and distributing No. 4 water tanks after the three-roll finish rolling, and carrying out alternating cooling on steel, wherein the No.1 water tanks adopt the opening degree of 45-85%, carrying out strong cooling, the No.2 and No. 3 water tanks carry out weak cooling, the opening degree of cooling water is 5-15%, the incoming material temperature of a finishing mill group is controlled to be 730-840 ℃, and two-phase zone rolling is carried out. After the material is discharged from the finishing mill group, the cooling intensity is properly increased, the opening degree of cooling water is increased to 40-60%, and the temperature of the material on a cooling bed is ensured to be 720-800 ℃. By the above rolling method, the steel material is ensured to have the highest possible internal distortion energy. And after rolling, the steel is quickly put on a cooling bed and sheared or cut off.
After the steel is taken off line and bundled, a rapid annealing furnace is used for rapid spheroidizing annealing treatment, and rapid spheroidizing is also one of the core procedures of the invention. Because the steel is rolled at ultralow temperature, a large amount of distortion energy exists in the rolled steel, the cementite sheets in pearlite are in a metastable state, fusing is easy to occur during reheating, the down-line bar steel is directly put into an annealing furnace for heat preservation, the heat preservation temperature is 710-760 ℃, the spheroidizing heat preservation temperature is a sensitive process, the temperature interval of the optimal process effect is very narrow, the temperature is too low, the cementite sheets are not suitable for fusing, the temperature is too high, a large amount of cementite is dissolved in austenite, and is re-separated out during the subsequent transformation, so that spheroidization is also not facilitated. The target value of the heat preservation temperature is adjusted according to the steel components so as to achieve the optimal effect. In order to avoid that a large amount of cementite sheets are dissolved into austenite during heat preservation, the heat preservation time is not suitable to be too long, and the heat preservation time is 120-150 min. And then cooling to 670-720 ℃ at the speed of 1 ℃ per minute for isothermal transformation, preserving heat for 150-180 minutes, and discharging from the furnace for natural cooling. The whole spheroidizing treatment time is 5.5-6.5 hours, which is equivalent to the common softening annealing process, but the softening annealing is of lamellar pearlite structure, which is unfavorable for cold forming processing with large deformation. Compared with the traditional spheroidizing annealing process (12-24 h), the treatment time is greatly shortened, and the energy consumption is greatly reduced.
Compared with the prior art, the invention has the advantages that:
the rapid spheroidized steel structure obtained by the invention is punctiform spheroidized body and ferrite or punctiform spheroidized body and ferrite and a small amount of lamellar cementite (the lamellar cementite accounts for less than 10 percent of the total cementite and is in dispersive distribution).
The rapid spheroidizing medium carbon rod steel realizes tissue spheroidization, reduces steel hardness, greatly improves cold forming performance and is beneficial to cold forging of complex parts by specific chemical component design, low-temperature heating, controlled rolling and cooling, ultralow-temperature finish rolling, rapid spheroidizing and other processes.
Drawings
FIG. 1 is a microstructure of a rapidly spheroidized medium carbon steel bar according to example 1 of the present invention.
FIG. 2 is a microstructure of a rapidly spheroidized medium carbon steel bar according to example 2 of the present invention.
FIG. 3 is a microstructure of a rapidly spheroidized medium carbon steel bar according to example 3 of the present invention.
Detailed Description
The present invention is further illustrated by the following examples.
Examples 1 to 3
The following procedure was used to manufacture a rapidly spheroidized medium carbon steel bar according to examples 1-3 of the present invention:
1) Smelting, namely, carrying out external refining after smelting in a 100-ton steel-smelting furnace (converter or electric furnace), and carrying out vacuum degassing treatment on molten steel, wherein the mass percentages of all chemical elements are strictly controlled according to requirements.
2) Continuous casting, namely continuously casting into square billets with the thickness of 240mm multiplied by 240mm, controlling the superheat degree of a tundish to be 10-25 ℃, reinforcing water cooling of a crystallizer, and ensuring the thickness of an equiaxed fine crystal layer region of a casting blank. And advanced terminal electromagnetic stirring and advanced equipment and process under continuous casting and soft reduction are adopted in continuous casting. The chemical composition percentages of the obtained continuous casting billets are shown in the following table 1:
table 1 (wt.%), the balance being Fe and other unavoidable impurity elements
3) Heating, namely heating the blank in a step heating furnace, wherein the heating furnace comprises a preheating section, a heating section and a soaking section, the temperature of the preheating section is controlled to be 650-750 ℃, the temperature of the heating section is controlled to be 850-950 ℃, the temperature of the soaking section is controlled to be 950-1020 ℃, and the total heating time is more than 180 min.
4) And hot rolling, namely rolling at the initial temperature of 880-950 ℃ and the final temperature of 710-790 ℃ at ultralow temperature in a two-phase region, so as to ensure that a large amount of distortion energy is stored in the hot rolled steel, and be beneficial to fusing, dissolving and separating out of the subsequent cementite.
5) And (3) performing rapid spheroidization, namely performing rapid annealing furnace after hot rolling offline, preserving heat at 710-760 ℃ for 120-150 min, cooling to 670-720 ℃ at 1 ℃ per min, preserving heat for 150-180 min, and discharging and air cooling to room temperature.
Specific process parameters of a rapid spheroidizing medium carbon steel bar in the above examples are shown in table 2 below:
TABLE 2 important process parameters for continuous casting, heating, rolling, spheroidization, etc
Relevant tests were carried out on the rapidly spheroidized medium carbon steel bars of examples 1 to 3, and the mechanical properties are shown in Table 3 below:
As can be seen from Table 3, the hardness in the examples meets the target requirement of 160HBW or less, the tensile strength after rapid spheroidization is 545-582 MPa, the elongation after rapid spheroidization is 32-35.5%, and the specific heat rolling state is remarkably improved. The 80% cold heading process has no cracking phenomenon. The steel in the embodiment has good plasticity and structure, and is very beneficial to cold forming processing.
FIGS. 1-3 show the microstructure of the rapidly spheroidized medium carbon steel bars of examples 1-3. As can be seen from FIGS. 1 to 3, the microstructure of the steel is a punctiform spheroid + ferrite + a small amount of lamellar cementite. The proportion of the lamellar cementite is less than 10%, and the tissue is very favorable for large-deformation cold forming processing.
While the preferred embodiments of the present invention have been described in detail, it is to be clearly understood that the same may be varied in many ways by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (4)
1. A manufacturing method of a quick spheroidizing medium carbon rod steel is characterized in that the steel comprises, by mass, 0.30-0.60% of C, less than or equal to 0.40% of Si, 0.50-0.90% of Mn, less than or equal to 0.020% of P, less than or equal to 0.030% of S, less than or equal to 0.30% of Cr, less than or equal to 0.25% of Cu and Ni, and the balance of Fe and unavoidable impurity elements;
The method comprises the following steps:
1) Smelting
When molten steel conforming to the chemical components of steel is smelted in a converter or an electric furnace, slag is required to be produced quickly, the fluidity of the slag is increased, meanwhile, the temperature in the furnace is controlled to be less than or equal to 1670 ℃, the purity of the molten steel is controlled, and large-particle inclusions in the steel are reduced;
2) Continuous casting
Further controlling the purity of steel during continuous casting, controlling the fluctuation of the liquid level to be less than or equal to +/-5 mm, controlling the superheat degree to be at a middle lower limit, and controlling the cooling water quantity of a crystallizer to be at a middle upper limit at the target temperature of 10-25 ℃;
3) Heating
Heating the blank in a step-by-step heating furnace, controlling the temperature of a preheating section to be 650-750 ℃, controlling the temperature of a heating section to be 850-950 ℃, and controlling the temperature of a soaking section to be 950-1020 ℃, wherein the blank is heated fully and uniformly, and the total heating time is more than 180 min;
4) Rolling
After the billet leaves the heating furnace, performing high-pressure water descaling, wherein the initial rolling temperature after descaling is 880-950 ℃, and the final rolling temperature is controlled to be 710-790, so that two-phase zone final rolling is realized, and after rolling, the steel is rapidly fed into a cooling bed and sheared or cut off;
The rolling process adopts 25 continuous rolling units to carry out continuous rolling, wherein the 25 rolling units are respectively 6 roughing mills, 10 middle rolling mills, 4 pre-finishing mills and 5 finishing mills;
Spray cooling is carried out on a water tank 1 after middle rolling, water tanks 2 and 3 are distributed after pre-finish rolling, a water tank 4 is distributed after three-roller finish rolling, and steel is cooled alternately in strength and weakness, wherein the water tank 1 adopts the opening degree of 45-85%, the opening degree of cooling water of the water tank 2 and 3 is 5-15%, the feeding temperature of a finishing mill group is controlled to be 730-840 ℃, two-phase zone rolling is carried out, the opening degree of cooling water of the water tank 4 is 40-60%, and the temperature of the material on a cooling bed is 720-800 ℃;
5) Rapid spheroidization
And after the steel is taken off line and bundled, performing rapid spheroidizing annealing treatment by a rapid annealing furnace, wherein the whole spheroidizing treatment time is 5.5-6.5 h.
2. The method of claim 1, wherein the steel has a non-cracking limit upset rate of 80% or more, a steel elongation of 30% or more, and a steel reference hardness of 160HB or less.
3. The method of claim 1, wherein the steel structure is punctiform spheroidization body + ferrite or punctiform spheroidization body + ferrite + a small amount of lamellar cementite, wherein lamellar cementite accounts for less than 10% of total cementite and is distributed in a dispersive manner.
4. The method of claim 1, wherein the rapid spheroidizing process is characterized in that the steel bars which are taken off line are directly put into an annealing furnace for heat preservation, the heat preservation temperature is 710-760 ℃, the heat preservation time is 120-150 min, the steel bars are cooled to 670-720 ℃ at a speed of 1 ℃ per minute for isothermal transformation after heat preservation, and the steel bars are taken out of the furnace for natural cooling after heat preservation for 150-180 min.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310241369.0A CN116426818B (en) | 2023-03-14 | 2023-03-14 | A fast spheroidized medium carbon steel bar and its manufacturing method |
| PCT/CN2023/115134 WO2024187688A1 (en) | 2023-03-14 | 2023-08-28 | Rapid-spheroidization medium carbon bar steel and manufacturing method therefor |
| JP2024553450A JP2025532729A (en) | 2023-03-14 | 2023-08-28 | Rapidly spheroidized medium carbon steel bar and its manufacturing method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310241369.0A CN116426818B (en) | 2023-03-14 | 2023-03-14 | A fast spheroidized medium carbon steel bar and its manufacturing method |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN116426818A CN116426818A (en) | 2023-07-14 |
| CN116426818B true CN116426818B (en) | 2025-03-11 |
Family
ID=87078684
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310241369.0A Active CN116426818B (en) | 2023-03-14 | 2023-03-14 | A fast spheroidized medium carbon steel bar and its manufacturing method |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JP2025532729A (en) |
| CN (1) | CN116426818B (en) |
| WO (1) | WO2024187688A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116426818B (en) * | 2023-03-14 | 2025-03-11 | 江阴兴澄特种钢铁有限公司 | A fast spheroidized medium carbon steel bar and its manufacturing method |
| CN117327983B (en) * | 2023-10-10 | 2025-12-12 | 上海方隆金属材料有限公司 | Alloy materials for medium and high carbon rivet wire |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103966411A (en) * | 2013-01-24 | 2014-08-06 | 宝山钢铁股份有限公司 | Manufacturing method for medium-carbon cold forging steel rods and wires |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100543155C (en) * | 2006-09-27 | 2009-09-23 | 马鞍山钢铁股份有限公司 | An on-line spheroidizing rolling process for medium carbon steel |
| JP5576785B2 (en) * | 2010-12-28 | 2014-08-20 | 株式会社神戸製鋼所 | Steel material excellent in cold forgeability and manufacturing method thereof |
| WO2013183648A1 (en) * | 2012-06-08 | 2013-12-12 | 新日鐵住金株式会社 | Steel wire rod or bar steel |
| WO2014030327A1 (en) * | 2012-08-20 | 2014-02-27 | 新日鐵住金株式会社 | Round steel material for cold forging |
| CN104805258B (en) * | 2014-06-27 | 2017-02-01 | 河北工程大学 | 42CrMo steel fast spheroidizing annealing method |
| CN112981228A (en) * | 2021-01-20 | 2021-06-18 | 江阴兴澄特种钢铁有限公司 | Steel bar with good cold forging performance for transmission gear shaft and manufacturing method |
| CN112981233B (en) * | 2021-01-21 | 2022-04-29 | 江阴兴澄特种钢铁有限公司 | Low-silicon medium-carbon gear steel suitable for cold forging processing and manufacturing method thereof |
| CN113789478B (en) * | 2021-09-16 | 2022-12-30 | 湖南华菱湘潭钢铁有限公司 | Production method of cold heading steel bar |
| CN114134411B (en) * | 2021-10-12 | 2022-07-29 | 江阴兴澄特种钢铁有限公司 | Spheroidized annealed steel for low-temperature-resistant high-strength ball screw and manufacturing method thereof |
| CN114892071B (en) * | 2022-04-07 | 2023-10-24 | 江阴兴澄特种钢铁有限公司 | High-temperature carburized gear steel for new energy vehicle and manufacturing method |
| CN116426818B (en) * | 2023-03-14 | 2025-03-11 | 江阴兴澄特种钢铁有限公司 | A fast spheroidized medium carbon steel bar and its manufacturing method |
-
2023
- 2023-03-14 CN CN202310241369.0A patent/CN116426818B/en active Active
- 2023-08-28 WO PCT/CN2023/115134 patent/WO2024187688A1/en active Pending
- 2023-08-28 JP JP2024553450A patent/JP2025532729A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103966411A (en) * | 2013-01-24 | 2014-08-06 | 宝山钢铁股份有限公司 | Manufacturing method for medium-carbon cold forging steel rods and wires |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2025532729A (en) | 2025-10-03 |
| WO2024187688A1 (en) | 2024-09-19 |
| CN116426818A (en) | 2023-07-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN112981235B (en) | Hardened and tempered steel plate with yield strength of 420MPa grade for building structure and production method thereof | |
| CN110184525B (en) | High-strength Q500GJE quenched and tempered steel plate for building structure and manufacturing method thereof | |
| CN105839003B (en) | A kind of 180~200mm thickness EH36 steel plates of normalizing state delivery and preparation method thereof | |
| CN111424219B (en) | Method for manufacturing gear shaft steel capable of being directly subjected to cold forging | |
| CN104264064B (en) | A kind of special think gauge Q690 high strength structure plate and manufacture method thereof | |
| CN101768698A (en) | Low cost yield strength 700MPA level non-tempering processing high strength steel plate and manufacturing method thereof | |
| CN107604248B (en) | A kind of high intensity Q500GJD quenched and tempered state steel plate for building structure and its manufacturing method | |
| CN106939391A (en) | A kind of Ca microalloyings easy-cutting high strength fractured connecting rod steel and manufacture method | |
| CN115449703B (en) | Isothermal annealing gear steel bar applicable to cold forging and manufacturing method thereof | |
| CN116426818B (en) | A fast spheroidized medium carbon steel bar and its manufacturing method | |
| CN111647800A (en) | Preparation method of hot-rolled round steel capable of being directly cut | |
| CN114959420A (en) | Preparation method of non-quenched and tempered steel for cylinder of plastic molding machine for producing round billet | |
| CN116727437A (en) | Method for improving rolling rhythm of steel plate with yield strength of 690MPa | |
| CN118374733A (en) | Cold drawn steel wire suitable for 10.9-grade non-adjustable cold heading type fastener and manufacturing method thereof | |
| CN102418047B (en) | Non-quenched and tempered fatigue-resistant steel plate and manufacturing method thereof | |
| CN115522135A (en) | Method for regulating strength, toughness and uniformity of non-quenched and tempered steel with super-large section by cooperation of multi-stage precipitation and controlled rolling and controlled cooling | |
| CN114807750A (en) | Thin 500 MPa-grade low-yield-ratio high-toughness bridge steel plate and manufacturing method thereof | |
| CN117070853B (en) | Economical 550MPa grade hot-rolled steel plate and its elongation stability control method | |
| CN114990290B (en) | Ultrahigh-strength steel plate with yield strength not less than 1.30GPa and production method thereof | |
| CN114737136B (en) | Production method of high-strength high-toughness hot continuous rolling thin steel plate with Brinell hardness of 400HBW | |
| CN106222557B (en) | A kind of high efficiency, low cost 610MPa water power steel and its production method | |
| CN110938771A (en) | Hot-rolled steel plate for wheel with tensile strength of 630MPa and manufacturing method thereof | |
| CN115537678A (en) | Steel for high-temperature carburization gear and manufacturing method thereof | |
| CN105177426A (en) | Normalizing rolling high-temperature-resistant capacitor plate and production method thereof | |
| CN113957357A (en) | Hot-rolled wear-resistant steel and production method thereof |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |