Production method for controlling blanking sound cracks and stamping cracks of bearing steel for wagon balance

Abstract

The invention discloses a production method for controlling blanking cracking and stamping cracking of bearing steel for a wagon balance, which comprises the following steps of: removing stress in a manner of controlling continuous casting parameters and putting small-specification bearing steel into a pit for heat preservation after rolling, reducing cracking when the bearing steel enters a heating furnace, reducing the risk of bearing steel fracture when H is high, and reducing an annealing process; internal defects of casting blanks during processing of bearing manufacturers are reduced; the center porosity of the bearing steel casting blank is effectively controlled, the center density of the casting blank is obviously improved, and the problem of casting blank cracking is solved without adding annealing treatment. The main chemical components of the bearing steel comprise, by mass, 0.95%-1.05% of C, 0.15%-0.35% of Si, 0.25%-0.45% of Mn, 1.40%-1.65% of Cr, smaller than or equal to 0.075% of As, Sn and Pb and the like. By means of the bearing steel, the induction heating time of bearing machining of bearing manufacturers can be shortened to 6-9 s from original 13-20 s.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and relates to a production process and a processing technology of a high-density square billet continuous casting billet, and specifically to a production method for controlling the cracking and stamping cracking of bearing steel for weighbridges. Background Art

[0002] Bearing steel has the properties of fatigue resistance, wear resistance, high rigidity and certain corrosion resistance. It is mainly used to manufacture balls, rollers and bearing rings. GCr15 steel is one of them. Due to the high carbon content and alloy content of bearing steel, the temperature change in the solidification zone is large, which leads to a long solidification gap length. Therefore, serious center segregation or looseness will form during the solidification process. Center segregation or looseness has little effect on parts such as rollers and rings, but it is very harmful to the balls on the working surface. In addition, bearing steel has to withstand great pressure and friction, so there are strict requirements on the quality of its ingots and rolled products. In particular, the center density of the ingots and rolled products must be guaranteed, otherwise it will be difficult to ensure the safety and quality of bearing steel. Therefore, eliminating the center looseness of the ingot and improving the center density of the ingot are crucial to the production of high-quality bearing steel.

[0003] In the prior art, the patent application number CN201510788995.7, "A method for controlling the center looseness of a large-section heavy rail steel ingot", is mainly aimed at large-section heavy rail steel and has certain benefits for improving the quality of heavy rail steel. However, since the carbon content and alloy content of GCr15 bearing steel and heavy rail steel are very different, this patent is not suitable for GCr15 bearing steel with high carbon and alloy content. The patent application number 201610173116.4, "A method for controlling the center looseness of 30CrMo round tube steel ingot", is mainly aimed at round tubes and has certain benefits for improving the quality of 30CrMo round tube steel ingots, but some key technologies for controlling the center looseness and density of bearing steel continuous casting ingots are not involved. Summary of the invention

[0004] In order to solve the above-mentioned bottleneck problems existing in the prior art, the purpose of the present invention is to control the continuous casting parameters and the small-sized bearing steel after rolling into the pit for insulation, so as to finally realize the quality control of the steel for continuous casting square billet scale based on the existing process flow, and to remove stress and reduce the cracking when entering the heating furnace and the risk of bearing steel fracture when H is high by slowly cooling the small-sized bearing steel into the pit, thereby reducing the risk of annealing process and reducing the internal defects of the billet during processing by the bearing manufacturer, and to solve the billet quality problem by controlling the heating temperature and extending the time.

[0005] The present invention provides a method for improving the central density of a bearing steel ingot, so that the central looseness of the bearing steel ingot can be effectively controlled and the central density of the ingot can be significantly improved; at the same time, the problem of cracking of the ingot is solved without adding annealing treatment; in addition, the bearing steel obtained by adopting the technical solution of the present invention can reduce the induction heating time of bearing manufacturers in processing bearings from the original 13 to 20 seconds to 6 to 9 seconds.

[0006] In order to achieve the above-mentioned invention object, the present invention provides a production method for controlling the cracking and stamping cracking of bearing steel for weighbridges, and the production method includes the following technical solutions:

[0007] ① During the continuous casting process, the casting machine pulling speed is controlled at 1.0-1.1 m / min, the superheat of the tundish steel liquid is controlled at 20℃-25℃, and the pulling speed is maintained constant during the production process; the light pressure reduction method is adopted at the end of solidification, and the light pressure reduction amount is 11-13 mm.

[0008] Furthermore, the crystallizer vibration parameters: adopt sinusoidal vibration mode, crystallizer water volume control: 130~150m 3 / h.

[0009] Furthermore, the secondary cooling water specific water volume control is: total water volume 91.0~92.0L / min, specific water volume 0.26~0.28L / kg.

[0010] Furthermore, the crystallizer electromagnetic stirring parameter control is: 340-360A, 1-3Hz, without crystallizer center magnetic induction intensity ≥950GS;

[0011] Electromagnetic stirring parameter control at the end of the casting: 390~410A, 6~8Hz, without the magnetic induction intensity of the center of the crystallizer ≥1000GS;

[0012] Stirring method: alternating (10s~3s~10s).

[0013] Furthermore, the casting billet pressing parameters are controlled as follows: 1-2 mm, 2-3 mm, 2-3 mm, 4-5 mm, 1-2 mm, a total of 12 mm;

[0014] Insulation parameter control of insulated billet: insulated billet offline temperature ≥550℃, insulation time ≥30h.

[0015] ② Heating process: high temperature diffusion temperature 1200℃~1230℃, high temperature diffusion time 2.4~2.6h, total heating time 3~5h, furnace temperature 1190℃~1210℃.

[0016] ③Rolling process: The steel billet needs to be descaled by high-pressure water before rolling after leaving the heating furnace. The pressure range of high-pressure water descaling is 24~29MPa. After rolling, it is put into the insulation pit for insulation. The slow cooling of small bars off the line is divided into seasons. In summer, the slow cooling specifications of small bars are φ55mm~φ82mm, and in winter, the slow cooling specifications of small bars are φ50mm~φ82mm. The temperature of the cooling bed under the small bars is required to be 300℃~400℃.

[0017] Furthermore, the chemical composition mass content of the bearing steel is C: 0.95% ~ 1.05%, Si: 0.15% ~ 0.35%, Mn: 0.25% ~ 0.45%, Cr: 1.40% ~ 1.65%, Mo ≤ 0.10%, Ni ≤ 0.25%, Cu ≤ 0.25%, Alt ≤ 0.05%, P ≤ 0.025%, S ≤ 0.02%, O ≤ 0.0012%, Ti ≤ 0.005%, As ≤ 0.04%, Sn ≤ 0.04%, Pb ≤ 0.002%, As + Sn + Pb ≤ 0.075%, and the rest is Fe and unavoidable impurities.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides a production process for highly homogeneous continuous casting billets for bearing scales. By controlling the composition, continuous casting process parameters and heating parameters, rolling and post-rolling insulation technology nodes, a continuous casting billet for bearing scales with uniform composition and dense center is finally obtained. Among them, the center looseness rating below level 1 reaches 100%, and the shrinkage rating level 0 reaches 100%. In addition, because induction heating is mostly used during bearing processing, small-sized bearing steel cannot be annealed. After rolling, insulation measures are adopted in insulation pits to eliminate stress. On the one hand, it ensures the use of downstream users, and on the other hand, it also saves energy for steel mills; the induction heating time of bearing manufacturers is reduced from the original 13 to 20 seconds to 6 to 9 seconds.

[0020] In addition, the specifications and temperatures for slow cooling of small rods are specified according to the seasons, providing a technical reference for people in the same industry. The specifications for slow cooling of small rods in summer are φ55mm~φ82mm, and those in winter are φ50mm~φ82mm. The temperature of the cooling bed for small rods is required to be 300℃~400℃. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a low-magnification picture of the continuous casting slab obtained in Example 1;

[0022] Figure 2 This is a low-magnification picture of the continuous casting ingot produced in Example 2. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with specific examples, but the present invention is not limited in any way. To avoid redundant description, the raw materials in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.

[0024] A production method for controlling the cracking and stamping cracking of bearing steel for weighbridges, the method comprising the following technical solutions:

[0025] ① During the continuous casting process, the casting machine is controlled to have a constant pulling speed of 1.0-1.1 m / min, and the superheat of the tundish steel liquid is 20℃-25℃; a light reduction method is used at the end of solidification, with a reduction of 11-13 mm;

[0026] ② Heating process: high temperature diffusion temperature 1200℃~1230℃, high temperature diffusion time 2.4~2.6h, total heating time 3~5h, furnace temperature 1190℃~1210℃;

[0027] ③Rolling process: The billet is rolled after being descaled from the heating furnace. The descaling high-pressure water pressure is 24-29MPa. After rolling, it is placed in a holding pit for insulation. The temperature of the cooling bed under the small bar is required to be 300℃~400℃.

[0028] The chemical composition mass content of the bearing steel is C: 0.95% ~ 1.05%, Si: 0.15% ~ 0.35%, Mn: 0.25% ~ 0.45%, Cr: 1.40% ~ 1.65%, Mo ≤ 0.10%, Ni ≤ 0.25%, Cu ≤ 0.25%, Alt ≤ 0.05%, P ≤ 0.025%, S ≤ 0.02%, O ≤ 0.0012%, Ti ≤ 0.005%, As ≤ 0.04%, Sn ≤ 0.04%, Pb ≤ 0.002%, As + Sn + Pb ≤ 0.075%, and the rest is Fe and unavoidable impurities.

[0029] The matters not described in the following embodiments are the same as the description of the above specific implementation methods.

[0030] Example 1

[0031] A production method for controlling the cracking and stamping cracking of bearing steel for weighbridges, the production method comprising the following technical solutions:

[0032] ① During the continuous casting process, the casting machine pulling speed is controlled at 1.0m / min, the superheat of the tundish steel liquid is controlled at 20℃, and the pulling speed is maintained constant during the production process; the light pressure reduction method is adopted at the end of solidification, and the light pressure reduction amount is 11mm.

[0033] Crystallizer vibration parameters: Sinusoidal vibration mode, crystallizer water volume control: 130m 3 / h.

[0034] Secondary cooling water specific water volume control: total water volume 91.0L / min, specific water volume 0.26L / kg.

[0035] Crystallizer electromagnetic stirring parameter control: 340A, 1Hz, without crystallizer center magnetic induction intensity 950GS; ingot end electromagnetic stirring parameter control: 390A, 6Hz, without crystallizer center magnetic induction intensity 1000GS; stirring mode: alternating (10s~3s~10s).

[0036] Billet pressing parameters control: 1, 2, 3, 5, 1mm, a total of 12mm;

[0037] Insulation parameter control of insulated billet: insulated billet offline temperature 550℃, insulation time 30h.

[0038] ② Heating process: blank shape 210mm×210mm, high temperature diffusion temperature 1200℃, high temperature diffusion time 2.4h, total heating time 3h, furnace temperature 1190℃.

[0039] ③Rolling process: The steel billet needs to be descaled by high-pressure water before rolling after leaving the heating furnace. The pressure range of high-pressure water descaling is 24MPa. After rolling, it is put into the insulation pit for insulation. The slow cooling of small bars off the line is divided into seasons. In summer, the slow cooling specifications of small bars are φ55~φ82, and in winter, the slow cooling specifications of small bars are φ50~φ82. The temperature of the cooling bed under the small bars is required to be 300℃.

[0040] The size of the billet produced in Example 1 is 210*210 mm square billet, and a low-magnification billet image of the continuous casting billet is obtained, as shown in FIG. Figure 1 As shown; the chemical composition mass content of the bearing steel is C: 0.95%, Si: 0.15%, Mn: 0.25%, Cr: 1.40%, Mo: 0.10%, Ni: 0.25%, Cu: 0.25%, Alt: 0.05%, P: 0.020%, S: 0.018%, O: 0.0011%, Ti: 0.005%, As: 0.04%, Sn: 0.03%, Pb: 0.002%, As+Sn+Pb: 0.072%, and the rest is Fe and unavoidable impurities. By controlling the composition, continuous casting process parameters and heating parameters, rolling and post-rolling insulation technical nodes through the above production method, 210 cubic continuous casting billets with uniform composition and dense center for bearing scales are finally obtained; among them, the center porosity rating below level 1 reaches 100%, and the shrinkage rating level 0 reaches 100%; the induction heating time of the bearing manufacturer using this bearing steel is reduced from the original 13 to 20s to 6 to 9s.

[0041] Example 2

[0042] A production method for controlling the cracking and stamping cracking of bearing steel for weighbridges, the production method comprising the following technical solutions:

[0043] ① During the continuous casting process, the casting machine pulling speed is controlled at 1.05m / min, the superheat of the tundish steel liquid is controlled at 23℃, and the pulling speed is maintained constant during the production process; the light pressure reduction method is adopted at the end of solidification, and the light pressure reduction amount is 12mm.

[0044] Crystallizer vibration parameters: Sinusoidal vibration mode, crystallizer water volume control: 140m 3 / h.

[0045] Secondary cooling water specific water volume control: total water volume 91.7L / min, specific water volume 0.27L / kg.

[0046] Crystallizer electromagnetic stirring parameter control: 350A, 2Hz, without crystallizer center magnetic induction intensity 960GS; ingot end electromagnetic stirring parameter control: 400A, 7Hz, without crystallizer center magnetic induction intensity 1010GS; stirring mode: alternating (10s~3s~10s).

[0047] Billet pressing parameters control: 1, 2, 3, 5, 1mm, a total of 12mm;

[0048] Insulation parameter control of insulated billet: insulated billet offline temperature 560℃, insulation time 32h.

[0049] ② Heating process: blank shape 210mm×210mm, high temperature diffusion temperature 1220℃, high temperature diffusion time 2.5h, total heating time 4h, furnace temperature 1200℃.

[0050] ③Rolling process: The steel billet needs to be descaled by high-pressure water before rolling after leaving the heating furnace. The pressure range of high-pressure water descaling is 27MPa. After rolling, it is put into the insulation pit for insulation. The slow cooling of small bars off the line is divided into seasons. In summer, the slow cooling specifications of small bars are φ55~φ82, and in winter, the slow cooling specifications of small bars are φ50~φ82. The temperature of the cooling bed under the small bars is required to be 350℃.

[0051] The size of the billet produced in Example 2 is 210*210 mm square billet, and a low-magnification billet image of the continuous casting billet is obtained, as shown in FIG. Figure 2As shown; the chemical composition mass content of the bearing steel is C: 1.0%, Si: 0.25%, Mn: 0.35%, Cr: 1.50%, Mo: 0.08%, Ni: 0.20%, Cu: 0.21%, Alt: 0.03%, P: 0.021%, S: 0.010%, O: 0.0010%, Ti: 0.004%, As: 0.03%, Sn: 0.03%, Pb: 0.001%, As+Sn+Pb: 0.061%, and the rest is Fe and unavoidable impurities. By controlling the composition, continuous casting process parameters and heating parameters, rolling and post-rolling insulation technical nodes through the above production method, 210 cubic continuous casting billets with uniform composition and dense center for bearing scales are finally obtained; among them, the center porosity rating below level 1 reaches 100%, and the shrinkage rating level 0 reaches 100%; the induction heating time of the bearing manufacturer using this bearing steel is reduced from the original 13 to 20s to 6 to 9s.

[0052] Example 3

[0053] A production method for controlling the cracking and stamping cracking of bearing steel for weighbridges, the production method comprising the following technical solutions:

[0054] ① During the continuous casting process, the casting machine pulling speed is controlled at 1.1m / min, the superheat of the tundish steel liquid is controlled at 25℃, and the pulling speed is maintained constant during the production process; the light pressure reduction method is adopted at the end of solidification, and the light pressure reduction amount is 13mm.

[0055] Crystallizer vibration parameters: Sinusoidal vibration mode, crystallizer water volume control: 150m 3 / h.

[0056] Secondary cooling water specific water volume control: total water volume 92.0L / min, specific water volume 0.28L / kg.

[0057] Crystallizer electromagnetic stirring parameter control: 360A, 3Hz, without crystallizer center magnetic induction intensity 970GS; ingot end electromagnetic stirring parameter control: 410A, 8Hz, without crystallizer center magnetic induction intensity 1020GS; stirring mode: alternating (10s~3s~10s).

[0058] Billet pressing parameters control: 1, 2, 3, 5, 1mm, a total of 12mm;

[0059] Insulation parameter control of insulated billet: insulated billet offline temperature 570℃, insulation time 34h.

[0060] ② Heating process: blank shape 210mm×210mm, high temperature diffusion temperature 1230℃, high temperature diffusion time 2.6h, total heating time 5h, furnace temperature 1210℃.

[0061] ③Rolling process: The billet needs to be descaled by high-pressure water before rolling after leaving the heating furnace. The pressure range of high-pressure water descaling is 29MPa. After rolling, it is put into the insulation pit for insulation. The slow cooling of small bars off the line is divided into seasons. In summer, the slow cooling specifications of small bars are φ55~φ82, and in winter, the slow cooling specifications of small bars are φ50~φ82. The temperature of the cooling bed under the small bars is required to be 400℃.

[0062] The size of the ingot produced in Example 3 is a square ingot of 210*210 mm. The chemical composition mass content of the bearing steel is C: 1.05%, Si: 0.35%, Mn: 0.45%, Cr: 1.65%, Mo: 0.06%, Ni: 0.15%, Cu: 0.19%, Alt: 0.02%, P: 0.022%, S: 0.014%, O: 0.0009%, Ti: 0.003%, As: 0.02%, Sn: 0.02%, Pb: 0.002%, As+Sn+Pb: 0.042%, and the rest is Fe and unavoidable impurities. By controlling the composition, continuous casting process parameters and heating parameters, rolling and post-rolling insulation technical nodes through the above production method, 210 cubic continuous casting billets with uniform composition and dense center for bearing scales are finally obtained; among them, the center porosity rating below level 1 reaches 100%, and the shrinkage rating level 0 reaches 100%; the induction heating time of the bearing manufacturer using this bearing steel is reduced from the original 13 to 20s to 6 to 9s.

[0063] For any technician familiar with the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent embodiments with equivalent changes. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention should still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A production method for controlling the cracking and stamping cracking of bearing steel for weighbridges, characterized in that: The method comprises the following technical solutions: ① During the continuous casting process, the casting machine is controlled to have a constant pulling speed of 1.0-1.1 m / min, and the superheat of the tundish steel liquid is 20℃-25℃; a light reduction method is used at the end of solidification, with a reduction of 11-13 mm; ② Heating process: high temperature diffusion temperature 1200℃~1230℃, high temperature diffusion time 2.4~2.6h, total heating time 3~5h, furnace temperature 1190℃~1210℃; ③Rolling process: The billet is rolled after being descaled from the heating furnace. The descaling high-pressure water pressure is 24-29MPa. After rolling, it is placed in a heat preservation pit for heat preservation. The temperature of the cooling bed under the small billet is required to be 300℃~400℃. The chemical composition mass content of the bearing steel is C: 0.95% ~ 1.05%, Si: 0.15% ~ 0.35%, Mn: 0.25% ~ 0.45%, Cr: 1.40% ~ 1.65%, Mo ≤ 0.10%, Ni ≤ 0.25%, Cu ≤ 0.25%, Alt ≤ 0.05%, P ≤ 0.025%, S ≤ 0.02%, O ≤ 0.0012%, Ti ≤ 0.005%, As ≤ 0.04%, Sn ≤ 0.04%, Pb ≤ 0.002%, As + Sn + Pb ≤ 0.075%, and the rest is Fe and unavoidable impurities.

2. The production method according to claim 1, characterized in that Step ① During the continuous casting process, the crystallizer adopts a sinusoidal vibration mode, and the water volume of the crystallizer is 130-150m 3 / h.

3. The production method according to claim 1, characterized in that In the continuous casting process of step ①, the water volume of the secondary cooling water is controlled to be 91.0-92.0 L / min of total water volume and 0.26-0.28 L / kg of water volume.

4. The production method according to claim 1, characterized in that In step ①, during the continuous casting process, the electromagnetic stirring parameters of the crystallizer are 340-360A, 1-3Hz, and the magnetic induction intensity at the center of the non-crystallizer is ≥950GS; the electromagnetic stirring parameters at the end of the casting are controlled to be 390-410A, 6-8Hz, and the magnetic induction intensity at the center of the non-crystallizer is ≥1000GS; the stirring mode is alternating for 10s-3s-10s.

5. The production method according to claim 1, characterized in that: In step ①, during the continuous casting process, the billet pressing parameters are controlled to be 1-2 mm, 2-3 mm, 2-3 mm, 4-5 mm, 1-2 mm, a total of 12 mm; the billet insulation parameters are controlled to be the billet offline temperature ≥550°C and the insulation time ≥30 h.

6. The production method according to claim 1, characterized in that: During the rolling process of step ③, the slow cooling of the small bars off the line is divided into different seasons, with the specifications of the small bars slow cooling in summer being φ55mm~φ82mm and the specifications of the small bars slow cooling in winter being φ50mm~φ82mm.

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