A ferrous metallurgical rolling product processing

Abstract

The application relates to the technical field of ferrous metal manufacturing, in particular to a ferrous metal smelting and rolling product processing technology. The ferrous metal smelting and rolling product processing technology comprises the following steps: primary dephosphorization smelting, secondary dephosphorization smelting, decarburization smelting, nitrogen increasing treatment, continuous casting, annealing, quenching, rolling and finally coiling to obtain a high-nitrogen wear-resistant stainless steel rolling coil. The ferrous metal smelting and rolling product processing technology can promote the prepared stainless steel rolling coil to have excellent wear resistance.

Description

Technical Field

[0001] This application relates to the technical field of ferrous metal manufacturing, and more specifically, to a ferrous metal smelting and rolling process. Background Technology

[0002] Metals are substances that possess luster and good electrical and thermal conductivity, as well as mechanical properties. Metals are mainly divided into two categories: ferrous metals and non-ferrous metals. Ferrous metals primarily refer to iron and its alloys, such as steel, pig iron, ferroalloys, and cast iron, while metals other than ferrous metals are collectively referred to as non-ferrous metals.

[0003] High-carbon chromium martensitic stainless steel is a ferrous metal with extremely strong wear resistance. This type of steel mainly improves its wear resistance by increasing the carbon content. However, when the carbon content is too high, coarse eutectic carbides inevitably appear during smelting and solidification. These eutectic carbides are difficult to eliminate or refine through heat treatment, leading to stress concentration and fatigue spalling, which in turn reduces the wear resistance of the steel. Summary of the Invention

[0004] In order to improve the wear resistance of steel, this application provides a processing technology for ferrous metal smelting and rolling.

[0005] This application provides a ferrous metal smelting and rolling process, which adopts the following technical solution:

[0006] A process for processing ferrous metal smelting and rolling products includes the following steps:

[0007] S1. Mix and melt the various raw materials of wear-resistant stainless steel, then blow nitrogen from the bottom and oxygen from the top to carry out the first dephosphorization smelting for 8-12 minutes to obtain dephosphorized steel liquid.

[0008] S2. Bottom-blowing nitrogen gas and top-blowing nitrogen gas are used to perform secondary dephosphorization smelting for 1-2 minutes to obtain secondary dephosphorized steel liquid.

[0009] S3. Bottom-blowing nitrogen gas and top-blowing oxygen gas are used to decarburize the secondary dephosphorized steel liquid for 7-15 minutes to obtain decarburized steel liquid.

[0010] S4. Bottom-blowing nitrogen gas into the decarburized steel liquid for 4-6 minutes to obtain high-nitrogen refined steel liquid;

[0011] S5. High-nitrogen refined steel liquid is continuously cast to obtain high-nitrogen stainless steel billet;

[0012] S6. Place the high-nitrogen wear-resistant stainless steel billet into an annealing furnace at 400-500℃, heat it to 900-950℃ at a rate of 80-90℃ / h, hold it at that temperature for 7-9h, then cool it to 730-760℃ at a rate of 30-40℃ / h, hold it at that temperature for 5-6h, and finally cool it to 400-500℃ at a rate of 30-40℃ / h. Remove it from the furnace and air cool it to room temperature to obtain the spheroidized annealed high-nitrogen stainless steel billet.

[0013] S7. Place the spheroidizing annealed high-nitrogen stainless steel billet into a quenching furnace at 300-400℃, then heat it to 750-760℃ at a rate of 90-100℃ / h and hold it for 2-3 hours. Then continue to heat it to 1000-1100℃ at a rate of 90-100℃ / h and hold it for 40-60 minutes. Finally, cool it to 200-300℃ at a rate of 30-40℃ / h and hold it for 1-2 hours. Finally, remove it from the furnace and air cool it to room temperature to obtain a high-nitrogen wear-resistant stainless steel billet.

[0014] S8. The high-nitrogen wear-resistant stainless steel billet is rolled in five passes with thicknesses of 1.42mm, 1.25mm, 0.9mm, 0.7mm, 0.55mm and 0.5mm respectively. Finally, it is coiled to obtain a high-nitrogen wear-resistant stainless steel rolled coil.

[0015] At this point, carbon accounts for 0.80%-1.20% of the mass percentage of the high-nitrogen wear-resistant stainless steel rolled coil, and nitrogen accounts for 0.20%-0.60% of the mass percentage of the high-nitrogen wear-resistant stainless steel rolled coil.

[0016] When the carbon content is between 0.8% and 1.2%, relatively few coarse eutectic carbides are produced. The S1-S4 operation can add nitrogen to the steel. Nitrogen can strengthen the matrix in an interstitial form like carbon, but it will not cause intergranular carbide precipitation like carbon. It effectively improves the size and distribution of carbides, thereby improving the wear resistance of high-nitrogen wear-resistant stainless steel rolled coils.

[0017] Preferably, the wear-resistant stainless steel is composed of the following raw materials in the following mass percentages: C: 1.20-1.40%; Ni: 0.2-2.0%; Cr: 14-16%; W: 0.6-1.4%; V: 0.10-0.14%; Mo: 1.2-1.8%; Se: 0.12-0.18%; Cu: 0.3-0.6%; Ti: 0.2-0.4%; the remainder being Fe and unavoidable impurities.

[0018] Preferably, Cr, W, V and C are added in the form of a mixed solid solution.

[0019] Element C can interact with alloying elements Cr, W, and V to form MC and M. 23Carbide hard wear-resistant phases such as C6 and M7C3 (where M represents alloying elements such as Cr, W, and V, or their combination) can also be incorporated into the alloy matrix to play a solid solution strengthening role, thereby enhancing the wear resistance of high-nitrogen wear-resistant stainless steel rolled coils. Furthermore, the addition of Cr, W, V, and C in the form of a mixed solid solution can promote the easier formation of carbide hard wear-resistant phases, further enhancing the wear resistance of high-nitrogen wear-resistant stainless steel rolled coils.

[0020] Furthermore, when W and V are used in combination, W, V, and C will form high-melting-point, highly stable WC and VC carbides, thus contributing to the material's excellent strength and toughness even at high temperatures. Additionally, W diffuses slowly within the material matrix; therefore, during tempering, some W is expelled from the newly formed phase and accumulates at the interface front, controlling particle growth. V forms VC, which precipitates during tempering, creating a dispersed phase and promoting secondary hardening, while W promotes the dispersion hardening effect of V.

[0021] Preferably, Mo and Se are added in the form of a mixed solid solution.

[0022] When Mo and Se are mixed, a transition metal selenide, MoSe2, is formed. MoSe2 has a hexagonal layered crystal structure similar to graphite, which in turn promotes the excellent self-lubricating properties of high-nitrogen wear-resistant stainless steel rolled coils and further enhances the wear resistance of high-nitrogen wear-resistant stainless steel rolled coils.

[0023] Meanwhile, when Mo and V are used in combination, the Mo and V carbides will undergo a secondary hardening effect, thereby further refining the grain size of the material. In addition to enhancing the mechanical properties of the material itself, the addition of Ni can also synergize with Mo and V to further enhance the wear resistance of high-nitrogen wear-resistant stainless steel rolled coils.

[0024] Preferably, Cu and Ti are added in the form of a mixed solid solution.

[0025] By adopting the above technical solutions, Cu can improve the strength and toughness of the material, but it is prone to hot brittleness during hot working. When Cu is added together with Ti, Cu and Ti will form compounds such as Ti2Cu3, TiCu and Ti2Cu. These compounds all have high crystallization points and can act as non-spontaneous nucleation sites, thereby refining the microstructure and grains and further enhancing the wear resistance of high nitrogen wear-resistant stainless steel rolled coils.

[0026] Preferably, the mass percentage of Ni in the wear-resistant stainless steel is 0.2-0.4%.

[0027] Excessive addition of Ni will significantly reduce nitrogen solubility, and Ni will hinder the transformation of austenite to martensite during heat treatment, leading to an increase in the amount of retained austenite, which in turn affects the wear resistance of high-nitrogen wear-resistant stainless steel coils. Therefore, the Ni content should be 0.2-0.4%.

[0028] Preferably, S1-S4 are controlled by timing valves; the timing valve includes a gas supply pipe assembly and a control component. The gas supply pipe assembly includes a support, a lower nitrogen pipe, an upper nitrogen pipe, and an upper oxygen pipe. The upper nitrogen pipe and the upper oxygen pipe are mounted on the upper part of the support, and the lower nitrogen pipe is mounted on the lower part of the support. Each of the lower nitrogen pipe, the upper nitrogen pipe, and the upper oxygen pipe is equipped with a control valve. The control component drives the three control valves to open sequentially.

[0029] Preferably, the control component includes a drive motor, a connecting disk, an upper control ring, and a lower control ring. The drive motor is disposed within the bracket. The connecting disk is detachably connected to the output end of the drive motor. The upper control ring is fixedly connected to the upper end face of the connecting disk, and the lower control ring is disposed on the lower end face of the connecting disk. The lower control ring includes a lower standby area and an opening area. The opening area is used to control the opening of the control valve on the lower nitrogen pipe. The upper control ring includes an upper standby area arranged sequentially. The system comprises a primary dephosphorization zone, a secondary dephosphorization zone, a decarbonization zone, and a nitrogen enrichment zone. The upper standby zone and the lower standby zone have the same angle and position. The primary dephosphorization zone is used to open the control valve of the upper oxygen pipe during operation S1. The secondary dephosphorization zone is used to open the control valve of the upper nitrogen pipe during operation S2. The decarbonization zone is used to open the control valve of the upper oxygen pipe during operation S3. The nitrogen enrichment zone is used to close the control valves of the upper oxygen pipe and the upper nitrogen pipe during operation S4.

[0030] Preferably, the control valve includes a valve seat, a cover plate, a compression spring, a sliding block, and a control block. The valve seat has a sliding groove, and two opposite sidewalls of the sliding groove have pipe openings. The sliding block is slidably connected to the sliding groove, and the sidewall of the sliding block always abuts against the groove wall of the sliding groove. The diameter of the pipe opening is smaller than the width of the sliding block.

[0031] The cover plate is fixedly connected to the opening of the sliding groove, the compression spring is housed in the sliding groove, one end of the compression spring is connected to the sliding block, and the other end of the compression spring is connected to the cover plate. The compression spring always forces the sliding block to seal the pipe opening.

[0032] The control block is provided with a connecting shaft, which passes through the valve seat and is connected to the sliding block. The control block is provided with a guide surface on the side away from the connecting shaft. The upper control ring or the lower control ring drives the sliding block to move and release the blockage of the pipe opening through the guide surface.

[0033] When S1-S4 operations are required, the operator can directly turn on the drive motor. The drive motor first drives the connecting disc to rotate. When the lower opening area comes into contact with the guide surface of the control valve on the lower nitrogen pipe, the lower opening area forces the control block to move downward through the guide surface. The control block then drives the sliding block to move downward through the connecting shaft, thereby causing the sliding block to release the blockage of the pipe opening. After that, the lower nitrogen pipe can continue to deliver nitrogen.

[0034] Simultaneously, the primary dephosphorization zone first contacts the guide surface on the upper oxygen pipe, allowing continuous oxygen delivery. Then, the primary dephosphorization zone disengages from the guide surface, and the compression spring forces the sliding block to reset and re-seal the pipe opening. The secondary dephosphorization zone then contacts the guide surface on the upper nitrogen pipe, allowing continuous nitrogen delivery while the upper oxygen pipe stops supplying gas. Next, the secondary dephosphorization zone disengages from the guide surface on the upper nitrogen pipe, and the compression spring forces the sliding block to reset and re-seal the pipe opening. The decarbonization zone then contacts the guide surface on the upper oxygen pipe, allowing oxygen delivery to resume while the upper nitrogen pipe stops supplying gas. Finally, the decarbonization zone disengages from the guide surface on the upper oxygen pipe, and the compression spring forces the sliding block to reset and re-seal the pipe opening, thus ending the gas delivery operations of both the upper nitrogen and upper oxygen pipes.

[0035] In summary, this application has the following beneficial effects:

[0036] 1. Nitrogen can strengthen the matrix in an interstitial manner, just like carbon, but it does not cause intergranular carbide precipitation like carbon does. It effectively improves the size and distribution of carbides, thereby enhancing the wear resistance of high-nitrogen wear-resistant stainless steel rolled coils.

[0037] 2. Element C can interact with alloying elements Cr, W, and V to form MC and M. 23 C6, M7C3 (M represents alloying elements such as Cr, W, V, or their composites) and other carbide hard wear-resistant phases can also be incorporated into the alloy matrix to play a solid solution strengthening role, thereby enhancing the wear resistance of high nitrogen wear-resistant stainless steel rolled coils.

[0038] 3. When Mo and Se are mixed, a transition metal selenide, MoSe2, is formed. MoSe2 has a hexagonal layered crystal structure similar to graphite, which promotes the high-nitrogen wear-resistant stainless steel rolled coil to obtain excellent self-lubricating properties and further enhances the wear resistance of the high-nitrogen wear-resistant stainless steel rolled coil.

[0039] 4. In S1-S4, the setting of the timing valve can make the gas supply operation at the top and bottom more stable and accurate, saving the staff the process of manually timing and supplying gas. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the timing valve.

[0041] Figure 2 This is a schematic diagram of the gas pipeline assembly;

[0042] Figure 3 This is a structural schematic diagram of the control component;

[0043] Figure 4 This is a schematic diagram of an explosion controlling a valve;

[0044] Figure 5 This is a schematic diagram of an explosion controlling the valve in the other direction.

[0045] Reference numerals: 1. Gas supply pipe assembly; 2. Control component; 11. Support; 12. Lower nitrogen pipe; 13. Upper nitrogen pipe; 14. Upper oxygen pipe; 15. Control valve; 21. Drive motor; 22. Connecting disc; 23. Upper control ring; 24. Lower control ring; 151. Valve seat; 152. Cover plate; 153. Compression spring; 154. Sliding block; 155. Control block; 156. Sliding groove; 157. Pipe opening; 158. Insertion groove; 231. Upper standby area; 232. Primary dephosphorization area; 233. Secondary dephosphorization area; 234. Decarbonization area; 235. Nitrogen enrichment area; 241. Lower standby area; 242. Opening area; 1521. Limiting groove; 1541. Limiting ring; 1551. Connecting shaft; 1552. Guide surface. Detailed Implementation

[0046] The following is in conjunction with the appendix Figure 1-5 The present application will be further described in detail with reference to Examples 1-9.

[0047] raw material

[0048] C CAS:7440-44-0;Ni CAS:14332-32-2;Cr CAS:7440-47-3;W CAS:7440-33-7;VCAS:7440-62-2;Mo CAS:7439-98-7;Se CAS:7782-49-2;Cu CAS:7440-50-8;Ti CAS: 7440-32-6; Fe CAS: 7439-89-6.

[0049] Example

[0050] Example 1

[0051] A process for processing ferrous metal smelting and rolling products includes the following steps:

[0052] S1. The raw materials for wear-resistant stainless steel are mixed and melted at 1900℃, and then... (The sentence is incomplete and requires more context to translate accurately.) 3 Nitrogen gas is bottom-purged at a flow rate of / t / min, while simultaneously at 1.5Nm 3 Oxygen was blown at a flow rate of / t / min to perform the first dephosphorization smelting for 10 minutes, resulting in dephosphorized steel liquid.

[0053] The wear-resistant stainless steel is composed of the following raw materials in the following mass percentages: C: 1.30%; Ni: 1.0%; Cr: 15%; W: 1.0%; V: 0.12%; Mo: 1.6%; Se: 0.15%; Cu: 0.45%; Ti: 0.3%; the remainder being Fe and unavoidable impurities.

[0054] S2, for primary dephosphorization of molten steel at 0.6 Nm 3 Nitrogen gas is bottom-blown at a flow rate of / t / min, while simultaneously being 1.6 Nm³. 3 Top-blown nitrogen at a flow rate of / t / min is used for secondary dephosphorization smelting for 1.5min to obtain secondary dephosphorized steel liquid;

[0055] S3, for secondary dephosphorization of molten steel at 0.6 Nm 3 Nitrogen gas is bottom-purged at a flow rate of / t / min, while simultaneously at 1.5Nm 3 Top-blown oxygen at a flow rate of / t / min was used for decarburization smelting for 10 minutes to obtain decarburized steel liquid;

[0056] S4, for secondary decarburized steel liquid, at 0.6 Nm 3 Nitrogen gas was blown down at a flow rate of / t / min for 5 minutes to obtain high-nitrogen molten steel;

[0057] S5. High-nitrogen refined steel liquid is continuously cast to obtain high-nitrogen stainless steel billet;

[0058] S6. Place the high-nitrogen wear-resistant stainless steel billet into an annealing furnace at 450℃, heat it to 930℃ at a rate of 85℃ / h, hold it at that temperature for 8h, then cool it to 745℃ at a rate of 35℃ / h, hold it at that temperature for 5.5h, and finally cool it to 450℃ at a rate of 35℃ / h. Remove it from the furnace and air cool it to room temperature to obtain the spheroidized annealed high-nitrogen stainless steel billet.

[0059] S9. The spheroidized annealed high-nitrogen stainless steel billet is placed in a quenching furnace at 350°C, then heated to 755°C at a rate of 95°C / h and held for 2.5h. Then, the temperature is increased to 1050°C at a rate of 95°C / h and held for 50min. Finally, it is cooled to 250°C at a rate of 35°C / h and held for 1.5h. Finally, it is removed from the furnace and air-cooled to room temperature to obtain a high-nitrogen wear-resistant stainless steel billet.

[0060] S10. The high-nitrogen wear-resistant stainless steel billet is rolled in five passes with thicknesses of 1.42mm, 1.25mm, 0.9mm, 0.7mm, 0.55mm and 0.5mm respectively. Finally, it is coiled to obtain a high-nitrogen wear-resistant stainless steel rolled coil.

[0061] At this point, carbon accounts for 1% of the mass percentage of the high-nitrogen wear-resistant stainless steel rolled coil, and nitrogen accounts for 0.40% of the mass percentage of the high-nitrogen wear-resistant stainless steel rolled coil.

[0062] S1-S4 are controlled by timing valves, and the specific structure of the timing valves is as follows:

[0063] Reference Figure 1 and Figure 2 The timing valve includes a gas supply pipe assembly 1 and a control component 2. The gas supply pipe assembly 1 includes a support 11, a lower nitrogen pipe 12, an upper nitrogen pipe 13, and an upper oxygen pipe 14. The upper nitrogen pipe 13 is mounted on the upper part of the support 11, and the lower nitrogen pipe 12 is mounted on the lower part of the support 11. Each of the lower nitrogen pipe 12, the upper nitrogen pipe 13, and the upper oxygen pipe 14 is equipped with a control valve 15. The control component 2 drives the three control valves 15 to open sequentially.

[0064] Reference Figure 1 and Figure 3 The control component 2 includes a drive motor 21, a connecting disk 22, an upper control ring 23, and a lower control ring 24. The drive motor 21 is installed inside the bracket 11, and the connecting disk 22 is detachably connected to the output shaft of the drive motor 21. The upper control ring 23 is fixedly connected to the upper end face of the connecting disk 22, and the lower control ring 24 is fixedly connected to the lower end face of the connecting disk 22.

[0065] The lower control ring 24 includes a lower standby area 241 and an open area 242. The open area 242 is used to control the opening of the control valve 15 on the lower nitrogen pipe 12. The upper control ring 23 includes an upper standby area 231, a primary dephosphorization area 232, a secondary dephosphorization area 233, a decarbonization area 234, and a nitrogen enrichment area 235 arranged sequentially. The upper standby area 231 has the same angle and position as the lower standby area 241. The primary dephosphorization area 232 is used to open the control valve 15 of the upper oxygen pipe 14 during operation S1. The secondary dephosphorization area 233 is used to open the control valve 15 of the upper nitrogen pipe 13 during operation S2. The decarbonization area 234 is used to open the control valve 15 of the upper oxygen pipe 14 during operation S3. The nitrogen enrichment area 235 is used to close the control valves 15 of both the upper oxygen pipe 14 and the upper nitrogen pipe 13 during operation S4. It should be noted that the angles of the primary dephosphorization zone 232, the secondary dephosphorization zone 233, the decarbonization zone 234, and the nitrogen enrichment zone 235 can be arbitrarily set according to the gas transmission time.

[0066] Reference Figure 4 and Figure 5 The control valve 15 includes a valve seat 151, a cover plate 152, a compression spring 153, a sliding block 154, and a control block 155. The end face of the valve seat 151 is provided with a sliding groove 156. The two opposite groove walls of the sliding groove 156 are provided with pipe openings 157. The sliding block 154 is slidably connected in the sliding groove 156. The side wall of the sliding block 154 is always in contact with the groove wall of the sliding groove 156. The diameter of the pipe opening 157 is smaller than the width of the sliding block 154.

[0067] The valve seat 151 has a insertion groove 158 on its side wall, which is connected to the sliding groove 156. The cover plate 152 is inserted and fixed in the insertion groove 158. The sliding block 154 is fixedly connected to the side of the cover plate 152 with a limit ring 1541. The cover plate 152 has a limit groove 1521 on the side of the sliding block 154. The compression spring 153 is housed in the sliding groove 156. One end of the compression spring 153 is embedded in the limit ring 1541, and the other end of the compression spring 153 is embedded in the limit groove 1521. The compression spring 153 always forces the sliding block 154 to seal the pipe opening 157.

[0068] A connecting shaft 1551 is fixedly connected to one side of the control block 155. The connecting shaft 1551 passes through the valve seat 151 and is fixedly connected to the side of the sliding block 154 away from the cover plate 152. A guide surface 1552 is provided on the side of the control block 155 away from the connecting shaft 1551. The upper control ring 23 or the lower control ring 24 drives the sliding block 154 to move and contact the sealing of the pipe port 157 through the guide surface 1552.

[0069] When S1-S4 operations are required, the operator can directly turn on the drive motor 21. The drive motor 21 first drives the connecting disc 22 to rotate. When the lower opening area 242 abuts against the guide surface 1552 of the control valve 15 on the lower nitrogen pipe 12, the lower opening area 242 forces the control block 155 to move downward through the guide surface 1552. The control block 155 then drives the sliding block 154 to move downward through the connecting shaft 1551, thereby causing the sliding block 154 to release the blockage of the pipe opening 157. After that, the lower nitrogen pipe 12 can continue to perform nitrogen delivery operations.

[0070] Meanwhile, the primary dephosphorization zone 232 first abuts against the guide surface 1552 on the upper oxygen pipe 14, allowing the upper oxygen pipe 14 to continuously supply oxygen. Then, the primary dephosphorization zone 232 disengages from the guide surface 1552 on the upper oxygen pipe 14, and the compression spring 153 forces the sliding block 154 to reset and re-seal the pipe opening 157. The secondary dephosphorization zone 233 then abuts against the guide surface 1552 on the upper nitrogen pipe 13, allowing the upper nitrogen pipe 13 to continuously supply nitrogen, while the upper oxygen pipe 14 stops supplying gas. Afterward, the secondary dephosphorization zone 233 disengages from the guide surface 1552 on the upper nitrogen pipe 13, and the compression spring 153 forces the sliding block 154 to reset and re-seal the pipe opening 157. The decarbonization zone 234 then abuts against the guide surface 1552 on the upper oxygen pipe 14, allowing the upper oxygen pipe 14 to resume oxygen supply, while the upper nitrogen pipe 13 stops supplying gas. Finally, the decarbonization zone 234 disengages from the guide surface 1552 of the upper oxygen pipe 14, and the compression spring 153 forces the sliding block 154 to reset and re-seal the pipe opening 157, thereby ending the gas transmission operation of the upper nitrogen pipe 13 and the upper oxygen pipe 14.

[0071] It should be noted that, in this embodiment, the aforementioned fixed connection can be selected using conventional fixed connection methods such as integral molding, welding, or threaded connection, depending on the actual situation. Similarly, the aforementioned detachable connection can be selected using conventional detachable connection methods such as plug-in fixing or threaded connection, depending on the actual situation.

[0072] Example 2-3

[0073] The difference from Example 1 is that the mass percentage of each raw material in the wear-resistant stainless steel is different, as shown in Table 1.

[0074] Table 1. Mass percentage of each raw material in wear-resistant stainless steel in Examples 1-3

[0075]

[0076]

[0077] The mass percentages of carbon and nitrogen in the high-nitrogen wear-resistant stainless steel rolled coils prepared in Examples 1-3 are shown in Table 2.

[0078] Table 2. Carbon and nitrogen content of high-nitrogen wear-resistant stainless steel rolled coils in Examples 1-3

[0079] Example 1 Example 2 Example 3 C 1.02 1.17 0.81 N 0.41 0.19 0.63

[0080] Example 4

[0081] The difference from Example 1 is that Cr, W, V and C are added in the form of a mixed solid solution with a mixing melting temperature of 1900°C.

[0082] Example 5

[0083] The difference from Example 4 is that Mo and Se are added in the form of a mixed solid solution with a mixing melting temperature of 800°C.

[0084] Example 6

[0085] The difference from Example 5 is that Cu and Ti are added in the form of a mixed solid solution, and the mixing and melting temperature is 2000°C.

[0086] Example 7

[0087] The difference from Example 6 is that the mass percentage of Ni is 0.2%, and the missing amount is made up with Fe.

[0088] Example 8

[0089] The difference from Example 6 is that the mass percentage of Ni is 2.0%, and the increase is replaced by Fe.

[0090] Comparative Example

[0091] Comparative Example 1

[0092] The difference from Example 1 is that the S1-S5 operations are no longer performed.

[0093] Performance testing

[0094] I. Wear Resistance Test

[0095] Three samples were taken from Examples 1-8 and Comparative Example 1, respectively. The samples were then cut to the specified dimensions and their initial mass M0 was measured in accordance with GB / T 34501-2017 "Test Method for Wear Resistance of Hard Alloy". Wear resistance tests were then conducted to measure the final mass M1. Finally, the wear rate was calculated and the average value was taken: Wear rate = (M0-M1) / M0.

[0096] The test data are shown in Table 3.

[0097] Table 3. Wear resistance performance of Examples 1-8 and Comparative Example 1

[0098]

[0099]

[0100] Referring to Examples 1-3 and Comparative Example 1 and in conjunction with Table 3, it can be seen that the wear rate of Examples 1-3 is significantly reduced compared to Comparative Example 1. This indicates that the addition of nitrogen can significantly improve the wear resistance of steel. The reason for this is that nitrogen can strengthen the matrix in an interstitial form like carbon, but it does not cause intergranular carbide precipitation like carbon. It effectively improves the size and distribution of carbides, thereby enhancing the wear resistance of high-nitrogen wear-resistant stainless steel rolled coils.

[0101] Among Examples 1-3, the wear resistance of Example 1 is relatively outstanding. This indicates that when the raw materials for wear-resistant stainless steel are selected according to the mass ratio of Example 1, the high-nitrogen wear-resistant stainless steel rolled coils prepared will have better wear resistance.

[0102] Referring to Examples 1, 4-6, and Table 3, it can be seen that the wear resistance of Example 4 is further improved compared to Example 1. The reason for this is that element C can interact with alloying elements Cr, W, and V to form MC and M. 23 C6, M7C3 (M represents alloying elements such as Cr, W, V, or their composites) and other carbide hard wear-resistant phases can also be incorporated into the alloy matrix to play a solid solution strengthening role, thereby enhancing the wear resistance of high nitrogen wear-resistant stainless steel rolled coils.

[0103] Compared to Example 4, Example 5 further improves the wear resistance. The reason for this is that when Mo and Se are mixed, a transition metal selenide MoSe2 is formed. MoSe2 has a hexagonal layered crystal structure similar to graphite, which in turn promotes the high-nitrogen wear-resistant stainless steel rolled coil to obtain excellent self-lubricating properties, further enhancing the wear resistance of the high-nitrogen wear-resistant stainless steel rolled coil.

[0104] Compared to Example 5, Example 6 further improves the wear resistance. The reason for this is that Cu can improve the strength and toughness of the material, but it is prone to hot brittleness during hot working. When Cu is added together with Ti, Cu and Ti will form compounds such as Ti2Cu3, TiCu and Ti2Cu. These compounds all have high crystallization points and can act as non-spontaneous nucleation sites, thereby refining the structure and grains, and further enhancing the wear resistance of high nitrogen wear-resistant stainless steel rolled coils.

[0105] Referring to Examples 6-8 and Table 3, it can be seen that the wear resistance of Examples 7-8 is significantly worse than that of Example 6. The reason for this is that Ni can dissolve in the ferroalloy and act as a solid solution strengthener, thereby improving the alloy's strength and wear resistance. However, excessive Ni addition will significantly reduce nitrogen solubility, and Ni will hinder the transformation of austenite to martensite during heat treatment, leading to an increase in the amount of retained austenite, which in turn affects the wear resistance of the high-nitrogen wear-resistant stainless steel rolled coils.

[0106] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A ferrous metals smelting and rolling product processing process, characterized by, Includes the following steps: S1. Mix and melt the various raw materials of wear-resistant stainless steel, then blow nitrogen from the bottom and oxygen from the top to carry out the first dephosphorization smelting for 8-12 minutes to obtain dephosphorized steel liquid. S2. Bottom-blowing nitrogen gas and top-blowing nitrogen gas are used to perform secondary dephosphorization smelting for 1-2 minutes to obtain secondary dephosphorized steel liquid. S3. Bottom-blowing nitrogen gas and top-blowing oxygen gas are used to decarburize the secondary dephosphorized steel liquid for 7-15 minutes to obtain decarburized steel liquid. S4. Bottom-blowing nitrogen gas into the decarburized steel liquid for 4-6 minutes to obtain high-nitrogen refined steel liquid; S5. High-nitrogen refined steel liquid is continuously cast to obtain high-nitrogen stainless steel billet; S6. Place the high-nitrogen wear-resistant stainless steel billet into an annealing furnace at 400-500°C, heat it to 900-950°C at a rate of 80-90°C / h, hold it at that temperature for 7-9h, then cool it to 730-760°C at a rate of 30-40°C / h, hold it at that temperature for 5-6h, and finally cool it to 400-500°C at a rate of 30-40°C / h. Remove it from the furnace and air cool it to room temperature to obtain the spheroidized annealed high-nitrogen stainless steel billet. S7. Place the spheroidizing annealed high-nitrogen stainless steel billet into a quenching furnace at 300-400°C, then heat it to 750-760°C at a rate of 90-100°C / h and hold it for 2-3 hours. Then continue to heat it to 1000-1100°C at a rate of 90-100°C / h and hold it for 40-60 minutes. Finally, cool it to 200-300°C at a rate of 30-40°C / h and hold it for 1-2 hours. Finally, remove it from the furnace and air cool it to room temperature to obtain a high-nitrogen wear-resistant stainless steel billet. S8. The high-nitrogen wear-resistant stainless steel billet is rolled in five passes with thicknesses of 1.42mm, 1.25mm, 0.9mm, 0.7mm, 0.55mm and 0.5mm respectively. Finally, it is coiled to obtain a high-nitrogen wear-resistant stainless steel rolled coil. At this point, carbon accounts for 0.80%-1.20% of the mass of the high-nitrogen wear-resistant stainless steel rolled coil, and nitrogen accounts for 0.20%-0.60% of the mass of the high-nitrogen wear-resistant stainless steel rolled coil. The wear-resistant stainless steel is composed of the following raw materials in the following mass percentages: C: 1.20-1.40%; Ni: 0.2-2.0%; Cr: 14-16%; W: 0.6-1.4%; V: 0.10-0.14%; Mo: 1.2-1.8%; Se: 0.12-0.18%; Cu: 0.3-0.6%; Ti: 0.2-0.4%; the remainder being Fe and unavoidable impurities.

2. The ferrous metal smelting and rolling process according to claim 1, characterized in that: Cr, W, V and C are added in the form of a mixed solid solution.

3. The ferrous metal smelting and rolling process according to claim 1, characterized in that: Mo and Se are added in the form of a mixed solid solution.

4. The ferrous metal smelting and rolling process according to claim 1, characterized in that: Cu and Ti are added in the form of a mixed solid solution.

5. The ferrous metal smelting and rolling process according to claim 1, characterized in that: In the wear-resistant stainless steel, the mass percentage of Ni is 0.2-0.4%.

6. The ferrous metal smelting and rolling process according to claim 1, characterized in that: S1-S4 are controlled by timing valves; the timing valves include a gas supply pipe assembly (1) and a control component (2). The gas supply pipe assembly (1) includes a support (11), a lower nitrogen pipe (12), an upper nitrogen pipe (13), and an upper oxygen pipe (14). The upper nitrogen pipe (13) and the upper oxygen pipe (14) are mounted on the upper part of the support (11), and the lower nitrogen pipe (12) is mounted on the lower part of the support (11). Each of the lower nitrogen pipe (12), the upper nitrogen pipe (13), and the upper oxygen pipe (14) is equipped with a control valve (15). The control component (2) drives the three control valves (15) to open sequentially.

7. The ferrous metal smelting and rolling product processing technology according to claim 6, characterized in that: The control component (2) includes a drive motor (21), a connecting disk (22), an upper control ring (23), and a lower control ring (24). The drive motor (21) is disposed in the bracket (11). The connecting disk (22) is detachably connected to the output end of the drive motor (21). The upper control ring (23) is fixedly connected to the upper end face of the connecting disk (22). The lower control ring (24) is disposed on the lower end face of the connecting disk (22). The lower control ring (24) includes a lower standby area (241) and an opening area (242). The opening area (242) is used to control the opening of the control valve (15) on the lower nitrogen pipe (12). The upper control ring (23) includes an upper standby area (231) and a single-stage deactivation device (242). The system comprises a phosphorus zone (232), a secondary dephosphorization zone (233), a decarbonization zone (234), and a nitrogen enrichment zone (235). The upper standby zone (231) and the lower standby zone (241) have the same angle and position. The primary dephosphorization zone (232) is used to open the control valve (15) of the upper oxygen pipe (14) during operation S1. The secondary dephosphorization zone (233) is used to open the control valve (15) of the upper nitrogen pipe (13) during operation S2. The decarbonization zone (234) is used to open the control valve (15) of the upper oxygen pipe (14) during operation S3. The nitrogen enrichment zone (235) is used to close the control valve (15) of the upper oxygen pipe (14) and the control valve (15) of the upper nitrogen pipe (13) during operation S4.

8. The ferrous metal smelting and rolling process according to claim 7, characterized in that: The control valve (15) includes a valve seat (151), a cover plate (152), a compression spring (153), a sliding block (154), and a control block (155). The valve seat (151) has a sliding groove (156), and the two opposite side walls of the sliding groove (156) have openings (157). The sliding block (154) is slidably connected in the sliding groove (156), and the side wall of the sliding block (154) is always in contact with the groove wall of the sliding groove (156). The diameter of the opening (157) is smaller than the width of the sliding block (154). The cover plate (152) is fixedly connected to the opening of the sliding groove (156), the compression spring (153) is housed in the sliding groove (156), one end of the compression spring (153) is connected to the sliding block (154), and the other end of the compression spring (153) is connected to the cover plate (152). The compression spring (153) always forces the sliding block (154) to seal the opening (157). The control block (155) is provided with a connecting shaft (1551), which passes through the valve seat (151) and is connected to the sliding block (154). The control block (155) is provided with a guide surface (1552) on the side away from the connecting shaft (1551). The upper control ring (23) or the lower control ring (24) drives the sliding block (154) to move and release the blockage of the pipe opening (157) through the guide surface (1552).

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