Softening annealing production method for high-carbon chromium bearing steel hot-rolled wire rod

Abstract

The invention discloses a high-carbon chromium bearing steel hot-rolled wire rod softening annealing production method which comprises the steps that S1, a continuous casting billet is heated, the continuous casting billet of 160 * 160 mm or 200 * 240 mm is adopted, and heating comprises preheating, a heating section, a first soaking section and a second soaking section; s2, controlled rolling is conducted, specifically, the rolling starting temperature and the rolling finishing temperature are set, and the continuous casting blank is rolled into a hot-rolled wire rod with the diameter being 5.5-20 mm; s3, stelmor wire cooling is conducted, specifically, the toast temperature is set, controlled cooling is conducted through a fan, and the temperature of the hot-rolled wire rod is rapidly reduced to 680-720 DEG C; s4, softening and annealing in a heat-insulating tunnel, setting the temperature of the heat-insulating tunnel, the roller speed and the cooling speed, finally cooling to be lower than 550 DEG C, and taking out of the heat-insulating tunnel for air cooling; s5, packaging is conducted, specifically, the lost hot-rolled wire rods are packaged online, and the packaging pressure, the package length and the package diameter are set; and S6, checking. Through online waste heat continuous softening annealing production, on one hand, heat of the hot-rolled wire rod is fully utilized, on the other hand, the plasticity and toughness of the high-carbon chromium bearing steel hot-rolled wire rod are improved, and meanwhile the production cost in the heat treatment-wire drawing machining process is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a production method for softening and annealing a hot-rolled wire rod of a high-carbon chromium bearing steel. Background Art

[0002] High carbon chromium bearing steel is a commonly used high carbon low alloy bearing steel material with a carbon content of about 1% and an alloy content of about 2%. It has low content of harmful elements, high purity and good uniformity. It is the main raw material for manufacturing various basic parts such as bearing rings, rolling elements, and molds.

[0003] High carbon chromium bearing steel hot rolled wire rod is generally delivered in hot rolled state. Hot rolled high carbon chromium bearing steel has the disadvantages of high hardness, large residual stress, poor plastic toughness, etc., which is not conducive to direct drawing processing. Therefore, hot rolled high carbon chromium bearing steel hot rolled wire rod needs to be annealed before use.

[0004] Softening annealing is a heat treatment process that keeps the temperature for a certain period of time. It can be used for processing high-carbon and alloy steels that are difficult to process.

[0005] The patent with announcement number CN112355054B and name "A large-size high-carbon chromium bearing steel hot-rolled wire rod and high-speed wire production method" is to improve the disadvantages of large coils. It uses a high-speed wire production line, through the swing function of the laying machine and the Stelmor wire controlled cooling, to reduce the level of network carbides, achieve uniformity and regularity of the laying coils, and solve the problems of large-size hot-rolled wire rod packaging and network carbides. The hot-rolled wire rod still needs annealing before drawing and requires aging post-processing. The swing function of the laying machine increases the complexity of the production process and the requirements for equipment accuracy.

[0006] The current soft annealing process has the disadvantages of complex procedures and low working efficiency, and the high carbon chromium bearing steel hot-rolled wire rod has poor machinability. Summary of the invention

[0007] In order to solve the deficiencies of the prior art, the present invention provides a method for softening and annealing a hot-rolled wire rod of high-carbon chromium bearing steel.

[0008] A method for softening and annealing a hot-rolled wire rod of high carbon chromium bearing steel comprises the following steps:

[0009] S1: heating the continuous casting billet, using a continuous casting billet of 160*160mm or 200*240mm, the heating includes preheating, heating section, soaking section one and soaking section two;

[0010] S2: controlled rolling, setting the starting rolling temperature and the final rolling temperature, rolling the continuous casting into a hot-rolled wire rod of Φ5.5-20mm;

[0011] S3: Stelmore line cooling, setting the toast temperature, using the fan to control cooling, so that the temperature of the hot-rolled wire rod quickly drops to 680-720℃;

[0012] S4: Softening annealing in the insulation tunnel, setting the insulation tunnel temperature, roller speed and cooling speed and finally cooling to below 550°C, and air cooling out of the insulation tunnel;

[0013] S5: Packaging: pack the hot rolled wire rods online, and set the packing pressure, packing length and packing diameter.

[0014] S6: Inspection.

[0015] Furthermore, in step S1, the temperature of the preheating section is not higher than 850°C, the temperature of the heating section is 950-1050°C, the temperature of the first soaking section is 1160-1230°C, and the temperature of the second soaking section is 1180-1230°C; and the continuous casting billet is kept warm within the temperature range of 1180-1220°C in the high temperature section according to the size specifications of the continuous casting billet.

[0016] Furthermore, in step S2, the starting rolling temperature is 1090-1150°C, and the final rolling temperature is 820-880°C.

[0017] Furthermore, in step S3, the spinning temperature is 820-850°C.

[0018] Furthermore, in step S4, the temperature of the insulation tunnel is 680-720° C., the roller speed is 2.4-3.0 m / min, and the cooling rate is 2-2.4° C. / min.

[0019] Furthermore, in step S5, the packaging pressure is controlled to be 20-30 tons, the packaging length is 1.4-1.7 meters, and the packaging diameter is 1.1-1.5 meters.

[0020] Furthermore, the annealing production method further includes spraying the high carbon chromium bearing steel with modified polymethylsilazane between step S3 and step S4.

[0021] Furthermore, the molecular weight of the modified polymethylsilazane is 50-300 g / mol.

[0022] Further, the preparation steps of the modified polymethylsilazane include:

[0023] S1: Add 10-20 parts of toluene and 2-5 parts of dichloromethylsilane into a reaction kettle, introduce ammonia during the reaction, set process conditions 1, and filter to obtain intermediate 1;

[0024] S2: Add 20-40 parts of intermediate 1 and 1-5 parts of NaNH2 into a reactor, set process condition 2, and filter to obtain intermediate 2;

[0025] S3: 1-5 parts of toluene diisocyanate and 20-80 parts of the intermediate 2 obtained in step S2 are added to a reaction kettle, and process conditions 3 are set to obtain modified polymethylsilazane.

[0026] Furthermore, process condition 1 is a temperature of 60-100°C, a time of 1-48h, and washing with water to PH=7 after the reaction; process condition 2 is a temperature of 60-100°C, a time of 1-8h; process condition 3 is a reaction condition under a nitrogen environment, a temperature of 60-120°C, and a time of 30min-8h.

[0027] The beneficial effects of the present invention are: first, by high-temperature diffusion and controlled rolling and cooling of the continuous casting billet, the unevenness of carbides in the steel is eliminated or reduced; second, the heat of the hot-rolled wire rod itself is fully utilized to achieve energy recycling, perform waste heat softening annealing, and reduce energy consumption; third, the aging of the hot-rolled wire rod of high-carbon chromium bearing steel is shortened.

[0028] The online waste heat continuous softening annealing production method is an economical and efficient production method for high carbon chromium bearing steel hot rolled wire rods. Through the online waste heat continuous softening annealing production, on the one hand, the heat of the hot rolled wire rods can be fully utilized, and on the other hand, the plasticity and toughness of the high carbon chromium bearing steel hot rolled wire rods can be improved. At the same time, the production cost of the heat treatment-wire drawing process can be reduced, which meets the development needs of the market and enterprises.

[0029] The waste heat of the hot-rolled wire rod is utilized through an insulation tunnel to realize online waste heat softening annealing. This method realizes the reuse of energy and reduces energy consumption. At the same time, it improves the machinability of the hot-rolled wire rod of high carbon chromium bearing steel, reduces annealing and aging, and directly draws the wire rod, reducing processing costs. DETAILED DESCRIPTION

[0030] In order to clearly illustrate the technical features of this solution, this solution is described below through a specific implementation method.

[0031] Embodiment 1:

[0032] 160*160mm GCr15 continuous casting billet, rolled Φ5.5mm hot rolled wire rod, chemical composition see Table 1.

[0033] Table 1 Chemical composition of high carbon chromium bearing steel GCr15 (%)

[0034]

[0035] S1: Heating. Use 160*160mm continuous casting billet to heat the continuous casting billet, with the preheating section temperature at 790℃, the heating section at 1000℃, the soaking section at 1180℃, the soaking section at 1205℃, and the high temperature section at 1180~1210℃ for 80min, with a total furnace time of 160min, to promote uniform diffusion of carbides and reduce segregation.

[0036] S2: Controlled rolling. After the continuous casting billet is taken out of the furnace, it is dephosphorized by high-pressure water, the starting rolling temperature is 1105℃, the final rolling temperature is 855℃, and the continuous casting billet is rolled into Φ5.5mm hot-rolled wire rod.

[0037] S3: Stelmore wire cooling. The spinning temperature is 835℃, and the fan is used for rapid controlled cooling to cool the hot-rolled wire rod to 698℃, inhibiting the formation of network cementite, and quickly collecting it at the hot coiling station.

[0038] S4: Softening annealing in the insulation tunnel. After being collected, it enters the insulation tunnel with a temperature of 705°C, a roller speed of 2.4m / min, a cooling rate of 2.1°C / min, and air cooling at 495°C out of the insulation tunnel.

[0039] S5: Packing. The hot-rolled wire rods are packed online, with a packing pressure of 22 tons, a pack length of 1.6 meters, and a pack diameter controlled at 1.4 meters.

[0040] S5: Inspection.

[0041] Embodiment 2:

[0042] 200*240mm GCr15 continuous casting billet, rolled into Φ15mm hot rolled wire rod, chemical composition see Table 2.

[0043] Table 2 Chemical composition of high carbon chromium bearing steel GCr15 in Example 2 (%)

[0044]

[0045] S1: Heating. Use 200*240mm continuous casting billet to heat the continuous casting billet. The temperature of the preheating section is 750℃, the heating section is 1010℃, the first soaking section is 1190℃, and the second soaking section is 1210℃. Keep the temperature in the high temperature section within the range of 1190-1210℃ for 130min, and the total time in the furnace is 260min, so as to promote the uniform diffusion of carbides and reduce segregation.

[0046] S2: Controlled rolling. After the continuous casting billet is taken out of the furnace, it is dephosphorized by high-pressure water, the starting rolling temperature is 1120℃, the final rolling temperature is 865℃, and the continuous casting billet is rolled into Φ15mm hot-rolled wire rod.

[0047] S3: Stelmore wire cooling. The spinning temperature is 840℃, and the fan is used for rapid controlled cooling to cool the hot-rolled wire rod to 700℃, inhibiting the formation of network cementite, and quickly collecting it at the hot coiling station.

[0048] S4: Softening annealing in the insulation tunnel. After being collected, it enters the insulation tunnel with a temperature of 710°C, a roller speed of 2.5m / min, a cooling rate of 2.2°C / min, and air cooling at 499°C out of the insulation tunnel.

[0049] S5: Packing. The hot-rolled wire rods are packed online, with a packing pressure of 25 tons, a pack length of 1.65 meters, and a pack diameter controlled at 1.42 meters.

[0050] S6: Inspection.

[0051] Embodiment 3:

[0052] 200*240mm GCr15 continuous casting billet, rolled into Φ20mm hot rolled wire rod, chemical composition see Table 3.

[0053] Table 3 Chemical composition of high carbon chromium bearing steel GCr15 (%)

[0054]

[0055] S1: Heating. Use 200*240mm continuous casting billet to heat the continuous casting billet. The temperature of the preheating section is 810℃, the heating section is 1000℃, the first soaking section is 1195℃, and the second soaking section is 1200℃. Keep the temperature in the high temperature section within the range of 1190-1200℃ for 120min, and the total time in the furnace is 245min, so as to promote the uniform diffusion of carbides and reduce segregation.

[0056] S2: Controlled rolling. After the continuous casting billet is taken out of the furnace, it is dephosphorized by high-pressure water, the starting rolling temperature is 1115℃, the final rolling temperature is 870℃, and the continuous casting billet is rolled into Φ20mm hot-rolled wire rod.

[0057] S3: Stelmore wire cooling. The spinning temperature is 845℃, and the fan is used for rapid controlled cooling to cool the hot-rolled wire rod to 702℃, inhibiting the formation of network cementite, and quickly collecting it at the hot coiling station.

[0058] S4: Softening annealing in insulation tunnel. After collection, it enters the insulation tunnel with a temperature of 710℃, a roller speed of 2.4m / min, a cooling rate of 2.1℃ / min, and air cooling at 500℃ out of the insulation tunnel.

[0059] S5: Packing. The hot-rolled wire rods are packed online, with a packing pressure of 25 tons, a pack length of 1.65 meters, and a pack diameter controlled at 1.45 meters.

[0060] S6: Inspection.

[0061] Embodiment 4:

[0062] 200*240mm GCr15 continuous casting billet, rolled into Φ20mm hot rolled wire rod, chemical composition see Table 4.

[0063] Table 4 Chemical composition of high carbon chromium bearing steel GCr15 (%)

[0064]

[0065] The first step is to prepare modified polymethylsilazane

[0066] S1: 10 parts of toluene and 2 parts of dichloromethylsilane were added to a reaction kettle, and ammonia was introduced during the reaction at 60°C for 1 hour. After the reaction, the reaction was washed with water until the pH value was 7, and filtered to obtain intermediate 1;

[0067] S2: Add 20 parts of intermediate 1 and 1 part of NaNH2 into a reaction kettle at 60°C for 1 hour, and filter to obtain intermediate 2;

[0068] S3: 1 part of toluene diisocyanate and 20 parts of the intermediate 2 obtained in step S2 were put into a reaction kettle under a nitrogen environment at a temperature of 60° C. for 30 minutes to obtain modified polymethylsilazane.

[0069] Step 2: Preparation of wire rod

[0070] S1: Heating. Use 200*240mm continuous casting billet to heat the continuous casting billet. The temperature of the preheating section is 810℃, the heating section is 1000℃, the first soaking section is 1195℃, and the second soaking section is 1200℃. Keep the temperature in the high temperature section within the range of 1190~1200℃ for 120min, and the total time in the furnace is 245min, so as to promote the uniform diffusion of carbides and reduce segregation.

[0071] S2: Controlled rolling. After the continuous casting billet is taken out of the furnace, it is dephosphorized by high-pressure water, the starting rolling temperature is 1115℃, the final rolling temperature is 870℃, and the continuous casting billet is rolled into Φ20mm hot-rolled wire rod.

[0072] S3: Stelmore wire cooling. The spinning temperature is 845℃, and the fan is used for rapid controlled cooling to cool the hot-rolled wire rod to 702℃, inhibiting the formation of network cementite, and quickly collecting it at the hot coiling station.

[0073] S4: Softening annealing in insulation tunnel. The wire rod is sprayed with modified polymethylsilazane before entering the insulation tunnel. After being collected, it enters the insulation tunnel with a temperature of 710°C, a roller speed of 2.4m / min, a cooling rate of 2.1°C / min, and air cooling at 500°C out of the insulation tunnel.

[0074] S5: Packing. The hot-rolled wire rods are packed online, with a packing pressure of 25 tons, a pack length of 1.65 meters, and a pack diameter controlled at 1.45 meters.

[0075] S6: Inspection.

[0076] Embodiment 5:

[0077] 200*240mm GCr15 continuous casting billet, rolled into Φ20mm hot rolled wire rod, chemical composition see Table 5.

[0078] Table 5 Chemical composition of high carbon chromium bearing steel GCr15 (%)

[0079]

[0080] The first step is to prepare modified polymethylsilazane

[0081] S1: 20 parts of toluene and 5 parts of dichloromethylsilane were added to a reaction kettle, and ammonia was introduced during the reaction. The temperature was 100°C and the reaction time was 48 hours. After the reaction was completed, the mixture was washed with water until the pH value was 7, and filtered to obtain intermediate 1;

[0082] S2: Add 40 parts of intermediate 1 and 5 parts of NaNH2 into a reaction kettle at 100°C for 8 hours, and filter to obtain intermediate 2;

[0083] S3: 5 parts of toluene diisocyanate and 80 parts of the intermediate 2 obtained in step S2 were put into a reaction kettle under a nitrogen environment at a temperature of 120° C. for 8 hours to obtain modified polymethylsilazane.

[0084] Step 2: Preparation of wire rod

[0085] S1: Heating. Use 200*240mm continuous casting billet to heat the continuous casting billet. The temperature of the preheating section is 810℃, the heating section is 1000℃, the first soaking section is 1195℃, and the second soaking section is 1200℃. Keep the temperature in the high temperature section within the range of 1190~1200℃ for 120min, and the total time in the furnace is 245min, so as to promote the uniform diffusion of carbides and reduce segregation.

[0086] S2: Controlled rolling. After the continuous casting billet is taken out of the furnace, it is dephosphorized by high-pressure water, the starting rolling temperature is 1115℃, the final rolling temperature is 870℃, and the continuous casting billet is rolled into Φ20mm hot-rolled wire rod.

[0087] S3: Stelmore wire cooling. The spinning temperature is 845℃, and the fan is used for rapid controlled cooling to cool the hot-rolled wire rod to 702℃, inhibiting the formation of network cementite, and quickly collecting it at the hot coiling station.

[0088] S4: Softening annealing in insulation tunnel. The wire rod is sprayed with modified polymethylsilazane before entering the insulation tunnel. After being collected, it enters the insulation tunnel with a temperature of 710°C, a roller speed of 2.4m / min, a cooling rate of 2.1°C / min, and air cooling at 500°C out of the insulation tunnel.

[0089] S5: Packing. The hot-rolled wire rods are packed online, with a packing pressure of 25 tons, a pack length of 1.65 meters, and a pack diameter controlled at 1.45 meters.

[0090] S6: Inspection.

[0091] Embodiment 6:

[0092] 200*240mm GCr15 continuous casting billet, rolled into Φ20mm hot rolled wire rod, chemical composition see Table 6.

[0093] Table 6 Chemical composition of high carbon chromium bearing steel GCr15 (%)

[0094]

[0095] The first step is to prepare modified polymethylsilazane

[0096] S1: 15 parts of toluene and 3 parts of dichloromethylsilane were added to a reaction kettle, and ammonia was introduced during the reaction at 80°C for 24 hours. After the reaction, the reaction was washed with water until the pH value was 7, and the intermediate 1 was obtained by suction filtration;

[0097] S2: Add 30 parts of intermediate 1 and 3 parts of NaNH2 into a reaction kettle at 80°C for 5 hours, and filter to obtain intermediate 2;

[0098] S3: 4 parts of toluene diisocyanate and 60 parts of the intermediate 2 obtained in step S2 were put into a reaction kettle, under a nitrogen environment, at a temperature of 100° C. for 3 hours to obtain modified polymethylsilazane.

[0099] Step 2: Preparation of wire rod

[0100] S1: Heating. Use 200*240mm continuous casting billet to heat the continuous casting billet. The temperature of the preheating section is 810℃, the heating section is 1000℃, the first soaking section is 1195℃, and the second soaking section is 1200℃. Keep the temperature in the high temperature section within the range of 1190~1200℃ for 120min, and the total time in the furnace is 245min, so as to promote the uniform diffusion of carbides and reduce segregation.

[0101] S2: Controlled rolling. After the continuous casting billet is taken out of the furnace, it is dephosphorized by high-pressure water, the starting rolling temperature is 1115℃, the final rolling temperature is 870℃, and the continuous casting billet is rolled into Φ20mm hot-rolled wire rod.

[0102] S3: Stelmore wire cooling. The spinning temperature is 845℃, and the fan is used for rapid controlled cooling to cool the hot-rolled wire rod to 702℃, inhibiting the formation of network cementite, and quickly collecting it at the hot coiling station.

[0103] S4: Softening annealing in insulation tunnel. The wire rod is sprayed with modified polymethylsilazane before entering the insulation tunnel. After being collected, it enters the insulation tunnel with a temperature of 710°C, a roller speed of 2.4m / min, a cooling rate of 2.1°C / min, and air cooling at 500°C out of the insulation tunnel.

[0104] S5: Packing. The hot-rolled wire rods are packed online, with a packing pressure of 25 tons, a pack length of 1.65 meters, and a pack diameter controlled at 1.45 meters.

[0105] S6: Inspection.

[0106] Comparative Example 1:

[0107] 200*240mm GCr15 continuous casting billet, rolled into Φ20mm hot rolled wire rod, chemical composition see Table 7.

[0108] Table 7 Chemical composition of high carbon chromium bearing steel GCr15 (%)

[0109]

[0110] The first step is to prepare polymethylsilazane

[0111] S1: 15 parts of toluene and 3 parts of dichloromethylsilane were added to a reaction kettle, and ammonia was introduced during the reaction at 80°C for 24 hours. After the reaction, the reaction was washed with water until the pH value was 7, and the intermediate 1 was obtained by suction filtration;

[0112] S2: Add 30 parts of intermediate 1 and 3 parts of NaNH2 into a reaction kettle at 80°C for 5 hours, and filter to obtain polymethylsilazane.

[0113] Step 2: Preparation of wire rod

[0114] S1: Heating. Use 200*240mm continuous casting billet to heat the continuous casting billet. The temperature of the preheating section is 810℃, the heating section is 1000℃, the first soaking section is 1195℃, and the second soaking section is 1200℃. Keep the temperature in the high temperature section within the range of 1190~1200℃ for 120min, and the total time in the furnace is 245min, so as to promote the uniform diffusion of carbides and reduce segregation.

[0115] S2: Controlled rolling. After the continuous casting billet is taken out of the furnace, it is dephosphorized by high-pressure water, the starting rolling temperature is 1115℃, the final rolling temperature is 870℃, and the continuous casting billet is rolled into Φ20mm hot-rolled wire rod.

[0116] S3: Stelmore wire cooling. The spinning temperature is 845℃, and the fan is used for rapid controlled cooling to cool the hot-rolled wire rod to 702℃, inhibiting the formation of network cementite, and quickly collecting it at the hot coiling station.

[0117] S4: Softening annealing in insulation tunnel. Polymethylsilazane is used for spray treatment before the wire rod enters the insulation tunnel. After being collected, it enters the insulation tunnel with a temperature of 710°C, a roller speed of 2.4m / min, a cooling rate of 2.1°C / min, and air cooling at 500°C out of the insulation tunnel.

[0118] S5: Packing. The hot-rolled wire rods are packed online, with a packing pressure of 25 tons, a pack length of 1.65 meters, and a pack diameter controlled at 1.45 meters.

[0119] S6: Inspection.

[0120] Comparative Example 2:

[0121] 160*160mm GCr15 continuous casting billet, rolled Φ5.5mm hot rolled wire rod, chemical composition see Table 8.

[0122] Table 8 Chemical composition of high carbon chromium bearing steel GCr15 (%)

[0123]

[0124] S1: Heating. Use 160*160mm continuous casting billet to heat the continuous casting billet, with the preheating section temperature at 780℃, the heating section at 990℃, the soaking section at 1180℃, and the soaking section at 1200℃. Keep the temperature in the high temperature section at 1180-1200℃ for 75min, and the total furnace time is 150min, so as to promote the uniform diffusion of carbides and reduce segregation.

[0125] S2: Controlled rolling. After the continuous casting billet is taken out of the furnace, it is dephosphorized by high-pressure water, the starting rolling temperature is 1125℃, the final rolling temperature is 850℃, and the continuous casting billet is rolled into Φ5.5mm hot-rolled wire rod.

[0126] S3: Stelmore wire cooling. The spinning temperature is 830℃, and the fan is used to quickly control the cooling, so that the hot-rolled wire rod is cooled to 705℃, and then enters the insulation cover for slow cooling, and then is collected out of the cover after slow cooling.

[0127] S4: Packing. The collected hot-rolled wire rods are packed online, with a packing pressure of 32 tons, a pack length of 1.6 meters, and a pack diameter of 1.35 meters.

[0128] S5: Inspection.

[0129] Comparative Example 3:

[0130] 200*240mm GCr15 continuous casting billet, rolled into Φ20mm hot rolled wire rod, chemical composition see Table 9.

[0131] Table 9 Chemical composition of high carbon chromium bearing steel GCr15 (%)

[0132]

[0133] S1: Heating. Use 200*240mm continuous casting billet to heat the continuous casting billet. The temperature of the preheating section is 800℃, the heating section is 1020℃, the first soaking section is 1185℃, and the second soaking section is 1205℃. Keep the temperature in the high temperature section within the range of 1180-1210℃ for 125min, and the total time in the furnace is 250min, so as to promote the uniform diffusion of carbides and reduce segregation.

[0134] S2: Controlled rolling. After the continuous casting billet is taken out of the furnace, it is dephosphorized by high-pressure water, the starting rolling temperature is 1115℃, the final rolling temperature is 870℃, and the continuous casting billet is rolled into Φ18mm hot-rolled wire rod.

[0135] S3: Stelmore wire cooling. The spinning temperature is 845℃, and the fan is used to quickly control the cooling, so that the hot-rolled wire rod is cooled to 700℃, and then enters the insulation cover for slow cooling, and then is collected out of the cover after slow cooling.

[0136] S4: Packing. The collected hot-rolled wire rods are packed online, with a packing pressure of 35 tons, a pack length of 1.65 meters, and a pack diameter of 1.4 meters.

[0137] S5: Inspection.

[0138] Hot-rolled wire rods were prepared according to the methods of Examples 1-6 and Comparative Examples 1-3, and the wire rods prepared by each method were sampled for inspection, etc. The specific results are shown in Table 10.

[0139] Table 10 Test results

[0140]

[0141] It can be seen from the test results in Table 10 that the surface quality of the wire rods prepared in Examples 1-6 and Comparative Examples 1-3 are all qualified, and the network carbide level, band distribution level, and precipitate analysis level are all the same, indicating that the use of the waste heat continuous softening annealing process in the present invention is economical and efficient while meeting production needs.

[0142] From the comparison between Example 1-3 and Comparative Example 2-3, it can be seen that the decarburized layer of Example 1-3 is about 50% lower than that of Comparative Example 2-3, and the Brinell hardness is about 80% higher than that of Comparative Example 2-3.

[0143] From the comparison between Example 1-3 and Example 4-6, it can be seen that the decarburized layer of Example 4-6 is about 50% lower than that of Example 1-3, and the Brinell hardness is about 8% higher than that of Comparative Example 1-3.

[0144] From the comparison between Examples 4-6 and Comparative Example 1, it can be seen that the decarburized layer of Comparative Example 1 is about twice that of Examples 4-6, and the Brinell hardness is higher than that of Comparative Example 4-6.

[0145] By comparing Examples 4-6 with Examples 1-3, it can be seen that after spraying with modified polymethylsiloxane during the hot rolling process, it can be seen from the decarburization layer and Brinell hardness performance that Examples 1-3 are more beneficial than the performance of only passing through the insulation tunnel, which plays a positive role in the performance of the hot-rolled wire rod.

[0146] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0147] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for softening and annealing a hot-rolled wire rod of high carbon chromium bearing steel, characterized in that: The steps of the annealing production method include: S1: heating the continuous casting billet, using a continuous casting billet of 160*160mm or 200*240mm, the heating includes preheating, heating section, soaking section one and soaking section two; S2: controlled rolling, setting the starting rolling temperature and the final rolling temperature, rolling the continuous casting into a hot-rolled wire rod of Φ5.5-20mm; S3: Stelmore line cooling, setting the toast temperature, using the fan to control cooling, so that the temperature of the hot-rolled wire rod quickly drops to 680-720℃; S4: Softening annealing in the insulation tunnel, setting the insulation tunnel temperature, roller speed and cooling speed and finally cooling to below 550°C, and air cooling out of the insulation tunnel; S5: Packing: pack the hot-rolled wire rods online, and set the packing pressure, packing length and packing diameter; S6: Inspection.

2. The method for softening and annealing a hot-rolled high carbon chromium bearing steel wire rod according to claim 1, characterized in that: In step S1, the temperature of the preheating section is not higher than 850°C, the temperature of the heating section is 950-1050°C, the temperature of the first soaking section is 1160-1230°C, and the temperature of the second soaking section is 1180-1230°C; and the continuous casting billet is kept warm in the temperature range of 1180~1220°C in the high temperature section according to the size specifications of the continuous casting billet.

3. The method for softening and annealing a hot-rolled high carbon chromium bearing steel wire rod according to claim 1, characterized in that: In step S2, the starting rolling temperature is 1090-1150°C, and the finishing rolling temperature is 820-880°C.

4. The method for softening and annealing a hot-rolled high carbon chromium bearing steel wire rod according to claim 1, characterized in that: The spinning temperature in step S3 is 820-850°C.

5. The method for softening and annealing a hot-rolled high carbon chromium bearing steel wire rod according to claim 1, characterized in that: In step S4, the temperature of the insulation tunnel is 680-720° C., the roller speed is 2.4-3.0 m / min, and the cooling rate is 2-2.4° C. / min.

6. The method for softening and annealing a hot-rolled high carbon chromium bearing steel wire rod according to claim 1, characterized in that: In step S5, the packing pressure is controlled to be 20-30 tons, the pack length is 1.4-1.7 meters, and the pack diameter is 1.1-1.5 meters.

7. The method for softening and annealing a hot-rolled high carbon chromium bearing steel wire rod according to claim 1, characterized in that: The annealing production method further comprises spraying the high carbon chromium bearing steel with modified polymethylsilazane between step S3 and step S4.

8. The method for producing hot-rolled high carbon chromium bearing steel wire rod by softening annealing according to claim 7, characterized in that: The molecular weight of the modified polymethylsilazane is 50-300 g / mol.

9. The method for producing hot-rolled high carbon chromium bearing steel wire rod by softening annealing according to claim 8, characterized in that: The preparation steps of the modified polymethylsilazane include: S1: Add 10-20 parts of toluene and 2-5 parts of dichloromethylsilane into a reaction kettle, introduce ammonia during the reaction, set process conditions 1, and filter to obtain intermediate 1; S2: Add 20-40 parts of intermediate 1 and 1-5 parts of NaNH2 into a reactor, set process condition 2, and filter to obtain intermediate 2; S3: 1-5 parts of toluene diisocyanate and 20-80 parts of the intermediate 2 obtained in step S2 are added to a reaction kettle, and process conditions 3 are set to obtain modified polymethylsilazane.

10. The method for producing hot-rolled high carbon chromium bearing steel wire rod by softening annealing according to claim 9, characterized in that: The process condition 1 is a temperature of 60-100°C, a time of 1-48h, and washing with water to pH = 7 after the reaction; the process condition 2 is a temperature of 60-100°C, a time of 1-8h; the process condition 3 is a reaction condition under a nitrogen environment, a temperature of 60-120°C, and a time of 30min-8h.

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