Production method for improving acid corrosion resistance of bearing steel wire rod

Abstract

The invention provides a production method for improving the acid corrosion resistance of a bearing steel wire rod. The method sequentially comprises the steps of molten iron pretreatment, converter smelting, LF refining furnace refining, RH vacuum treatment, continuous casting, heating furnace heating, high-speed wire rolling and finished wire rod obtaining. In the continuous casting production process, a large rolling reduction mode is adopted for production, five sets of rolling reduction rollers are used for rolling reduction, and the total rolling reduction is specifically 25 mm; after the continuous casting process, a casting blank enters a heating furnace after being slowly cooled, the heating furnace adopts a three-section heating process, the temperature set value of a preheating section is 750-880 DEG C, the temperature of a heating section is 1000-1100 DEG C, the temperature of a soaking section is 1200-1250 DEG C, and rolling is carried out after the heat preservation time of the soaking section is 1.2-1.5 hours. The acid corrosion resistance of the bearing steel wire is greatly improved, the macrostructure of the whole bearing steel matrix does not have corrosion pits, the macrostructure rating of the wire is that the porosity is less than or equal to 0.5 grade, and the center porosity is less than or equal to 0.5 grade.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to a production method for improving the acid corrosion resistance of bearing steel wire. Background Art

[0002] Bearings are key basic components in the equipment manufacturing industry and are widely used in major equipment fields such as mining machinery, precision machine tools, metallurgical equipment, heavy equipment and high-end cars, as well as emerging industries such as wind power generation, high-speed rail vehicles and aerospace. Depending on the application field, some bearings need to work in harsh environments with strong acids, strong alkalis, strong impacts and strong loads, which places more stringent requirements on bearing steel materials.

[0003] Chinese Patent CN111074228 A: A composite surface treatment method for improving the corrosion resistance of bearing steel. This patent relates to a composite surface treatment method for improving the corrosion resistance of bearing steel. By first performing laser remelting and Cr ion implantation and then preparing a Cr layer, the bonding force between the Cr layer and the substrate is improved, thereby improving the corrosion resistance of the bearing steel. This patent mainly involves the field of steel surface treatment, improving the corrosion resistance of the bearing steel surface, and does not involve the bearing steel substrate.

[0004] Chinese patent CN116815056 A: A high-strength bearing steel with good corrosion resistance and its production method and heat treatment method. This patent achieves good corrosion resistance and high strength of bearing steel round steel by adding precious alloy elements such as Mo, Nb, Ni to the bearing steel, and then through heat treatment methods such as spheroidizing annealing, quenching and tempering. This patent mainly involves the production of bearing steel round steel, and adds more precious alloy elements such as Mo, Nb, Ni to improve corrosion resistance, which is costly.

[0005] Chinese patent CN111349866 A: A rolling process for corrosion-resistant bearing steel. The chemical composition of the bearing steel in this patent adds more precious alloy elements such as Cr, Ni, V, Mo, B, Ba, Ta, etc., so that the bearing steel has high strength, high resistance to intergranular corrosion, resistance to chloride stress corrosion and good welding performance, and prolongs the service life of the bearing steel and its products. This patent adds more precious alloys and rare metal elements and uses a KOCKS three-roller sizing unit for rolling, which has a high cost. Summary of the invention

[0006] In order to solve the problem that the prior art lacks improvement in the corrosion resistance of a bearing steel matrix, the present invention provides a production method for improving the acid corrosion resistance of a bearing steel wire.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a production method for improving the acid corrosion resistance of bearing steel wire, the production method comprises the following steps in sequence: molten iron pretreatment → converter smelting → LF refining furnace refining → RH vacuum treatment → continuous casting → heating furnace heating → high-speed wire rolling → finished wire, the bearing steel molten steel prepared by the converter and LF refining furnace is composed of the following components in weight percentage: C 0.95-1.05%, Si 0.15-0.35%, Mn 0.25-0.45%, P0.008-0.015%, S 0.001-0.005%, Ni 0.10-0.30%, Cr 1.40-1.65%, Cu0.10-0.30%, Al0.01-0.03%, Ti 0.001~0.002%, the balance is Fe and unavoidable impurities; after adjusting the ratio, nickel and copper alloy elements are added, and the sulfur content is reduced. Nickel is an element with good corrosion resistance, which can improve the corrosion resistance of steel in oxidizing media (such as seawater, salt water, sulfuric acid, etc.). Nickel can form a dense oxide film on the surface of steel to prevent the corrosive medium from further corroding the steel; copper can improve the corrosion resistance of steel to a certain extent, especially in corrosive media such as sulfur and phosphorus. The corrosion products formed by copper on the surface of steel have a certain protective effect. Sulfur mainly forms sulfide inclusions such as manganese sulfide (MnS) or iron sulfide (FeS) in steel. Sulfide inclusions are easy to become the starting point of corrosion in a corrosive environment, because these inclusions have different electrochemical properties from the steel matrix, forming a micro-battery effect, which accelerates the local corrosion process. Lowering the sulfur content can reduce the starting point of corrosion, reduce the corrosion rate of steel in a corrosive environment, and improve its corrosion resistance. In the continuous casting production process, a large reduction mode is adopted for production, and five groups of reduction rollers are used for reduction, and the specific reduction is 3.0mm-3.0mm-6.0mm-8.0mm-5.0mm. After the continuous casting process, the ingot enters the heating furnace after slow cooling. The heating furnace adopts a three-stage heating process, with a preheating section temperature setting value of 750-880°C, a heating section temperature of 1000-1100°C, a soaking section temperature of 1200-1250°C, and a soaking section insulation time of 1.2-1.5 hours before rolling.

[0008] Preferably, the pressure value of the continuous casting process varies due to different reduction amounts, and the fluctuation range is 2MPa to 13MPa.

[0009] Preferably, the method for pre-treating the molten iron is: desulfurizing the molten iron by the KR method before the molten iron enters the furnace, requiring the sulfur content of the molten iron entering the furnace to be ≤0.003% and the temperature of the molten iron entering the furnace to be ≥1350°C.

[0010] Preferably, the converter smelting method is: using a top and bottom combined blowing converter for smelting, requiring the steel tapping temperature to be ≥1620°C, and performing preliminary composition preparation and deoxidation and alloying operations during the steel tapping process according to the chemical composition requirements.

[0011] Preferably, the LF refining furnace refining method is: using the LF furnace for refining, slag deoxidation and accurate proportioning of alloy components, requiring the basicity of the refined slag to be controlled at 3-8, and the refining end temperature ≥1500°C.

[0012] Preferably, the RH vacuum treatment method is: using an RH furnace for vacuum degassing treatment, requiring the vacuum treatment time to be ≥30 minutes, and the temperature of the molten steel after the vacuum treatment to be ≥1500°C.

[0013] Preferably, the high-speed wire rolling method is: after the billet is heated by a heating furnace, it is rolled through a rough rolling unit, an intermediate rolling unit, a pre-finishing rolling unit, a finishing rolling unit, a sizing unit, a laying head, an air cooling line, and a coiling station.

[0014] Compared with the prior art, the advantages and positive effects of the present invention are that, in order to meet the acid corrosion resistance of bearing steel wire, this patent innovatively optimizes the design of bearing steel smelting composition, adopts large reduction to produce bearing steel ingots, and adopts a large compression ratio hole type in the rough rolling area during ingot rolling to produce bearing steel wire. Through this smelting and rolling method, the acid corrosion resistance of bearing steel wire is greatly improved, and pickling in a 1:1 (volume ratio) hot hydrochloric acid aqueous solution at 75°C for 30 minutes is achieved. No corrosion pits appear in the macrostructure of the entire bearing steel matrix (surface + cross section). According to the atlas test in Appendix A of GB / T 18254-2016 standard, the macrostructure rating of the wire is generally loose ≤0.5 level and central loose ≤0.5 level. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a low-magnification image of the pickling cross section of the wire produced by the production method of Example 1;

[0016] Figure 2 This is a low-magnification image of the pickling cross section of the wire produced by the production method of Example 2;

[0017] Figure 3 This is a low-magnification image of the pickling cross section of the wire produced by the production method of Example 3;

[0018] Figure 4 This is a low-magnification image of the pickling cross-section of the wire produced by the comparative production method.

[0019] Legend: DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example 1

[0022] This embodiment provides a production method for improving the acid corrosion resistance of bearing steel wire rod, and the production method includes the following steps in sequence: molten iron pretreatment → converter smelting → LF refining furnace refining → RH vacuum treatment → continuous casting → heating furnace heating → high wire rolling → finished wire rod. The method of molten iron pretreatment is: the KR method is used for desulfurization before the molten iron enters the furnace, and the sulfur content of the molten iron entering the furnace is required to be ≤0.003%, and the temperature of the molten iron entering the furnace is ≥1350°C. The method of converter smelting is: the top and bottom double-blowing converter is used for smelting, and the steel tapping temperature is required to be ≥1620°C. During the steel tapping process, preliminary composition formulation and deoxidation alloying operations are performed according to the chemical composition requirements. The method of refining in the LF refining furnace is: the LF furnace is used for refining, slag deoxidation and accurate proportioning of alloy components, and the basicity of the refined slag is required to be controlled at 3-8, and the refining end temperature is ≥1500°C. The method of RH vacuum treatment is: the RH furnace is used for vacuum degassing treatment, and the vacuum treatment time is required to be ≥30 minutes, and the temperature of the molten steel after vacuum treatment is ≥1500°C. The high-speed wire rolling method is as follows: after the billet is heated by a heating furnace, it is rolled through a rough rolling unit, an intermediate rolling unit, a pre-finishing rolling unit, a finishing rolling unit, a sizing unit, a laying head, an air cooling line, and a coiling station.

[0023] The bearing steel molten steel prepared by the converter and LF refining furnace is composed of the following components in weight percentage: C 0.95%, Si 0.24%, Mn 0.28%, P 0.010%, S 0.004%, Ni 0.14%, Cr 1.45%, Cu 0.18%, Al 0.015%, Ti 0.0012%, and the balance Fe and inevitable impurities.

[0024] The casting is carried out by a 6-machine 6-stream 180*240mm continuous casting machine. After the large reduction of 25mm process, five sets of reduction rollers are used to control the reduction according to the reduction of 3.0mm-3.0mm-6.0mm-8.0mm-5.0mm to produce qualified ingots.

[0025] After the ingot is slowly cooled for 36 hours, it is put into the furnace for rolling. The heating furnace adopts a three-stage heating process, with the preheating section temperature set at 800°C, the heating section temperature at 1100°C, and the soaking section temperature at 1250°C. The soaking section is kept warm for 1.4 hours before rolling. The high compression ratio 1# rolling mill is used for rough rolling, and the final rolling is φ10mm specification wire. The hydrochloric acid concentration (hydrochloric acid: water = 1:1), hydrochloric acid temperature of 75°C, and pickling time of 30 minutes are used for testing. Figure 1 As shown, there are no corrosion pits on the end face of the wire rod, and the acid corrosion resistance is significantly improved.

[0026] Example 2

[0027] This embodiment provides a production method for improving the acid corrosion resistance of bearing steel wire rod, and the production method includes the following steps in sequence: molten iron pretreatment → converter smelting → LF refining furnace refining → RH vacuum treatment → continuous casting → heating furnace heating → high wire rolling → finished wire rod. The method of molten iron pretreatment is: the KR method is used for desulfurization before the molten iron enters the furnace, and the sulfur content of the molten iron entering the furnace is required to be ≤0.003%, and the temperature of the molten iron entering the furnace is ≥1350°C. The method of converter smelting is: the top and bottom double-blowing converter is used for smelting, and the steel tapping temperature is required to be ≥1620°C. During the steel tapping process, preliminary composition formulation and deoxidation alloying operations are performed according to the chemical composition requirements. The method of refining in the LF refining furnace is: the LF furnace is used for refining, slag deoxidation and accurate proportioning of alloy components, and the basicity of the refined slag is required to be controlled at 3-8, and the refining end temperature is ≥1500°C. The method of RH vacuum treatment is: the RH furnace is used for vacuum degassing treatment, and the vacuum treatment time is required to be ≥30 minutes, and the temperature of the molten steel after vacuum treatment is ≥1500°C. The high-speed wire rolling method is as follows: after the billet is heated by a heating furnace, it is rolled through a rough rolling unit, an intermediate rolling unit, a pre-finishing rolling unit, a finishing rolling unit, a sizing unit, a laying head, an air cooling line, and a coiling station.

[0028] The bearing steel molten steel prepared by the converter and LF refining furnace is composed of the following components in weight percentage: C 0.98%, Si 0.35%, Mn 0.35%, P 0.015%, S 0.005%, Ni 0.30%, Cr 1.40%, Cu 0.30%, Al 0.010%, Ti 0.0010%, and the balance Fe and inevitable impurities.

[0029] The casting is carried out by a 6-machine 6-stream 200*200mm continuous casting machine. After the large reduction process of 25mm, five sets of reduction rollers are used to control the reduction according to the reduction of 3.0mm-3.0mm-6.0mm-8.0mm-5.0mm to produce qualified ingots.

[0030] After the ingot is slowly cooled for 36 hours, it is rolled into the furnace. The heating furnace adopts a three-stage heating process, with the preheating section temperature set at 750°C, the heating section temperature at 1000°C, the soaking section temperature at 1200°C, and the soaking section temperature at 1.2 hours before rolling. The rough rolling adopts a large compression ratio 1# rolling mill, and finally rolls into a φ6.5mm specification wire rod, and uses hydrochloric acid concentration (hydrochloric acid: water = 1:1), hydrochloric acid temperature of 75°C, and pickling time of 30 minutes for testing. Figure 2 As shown, there are no corrosion pits on the end face of the wire rod, and the acid corrosion resistance is significantly improved.

[0031] Example 3

[0032] This embodiment provides a production method for improving the acid corrosion resistance of bearing steel wire rod, and the production method includes the following steps in sequence: molten iron pretreatment → converter smelting → LF refining furnace refining → RH vacuum treatment → continuous casting → heating furnace heating → high wire rolling → finished wire rod. The method of molten iron pretreatment is: the KR method is used for desulfurization before the molten iron enters the furnace, and the sulfur content of the molten iron entering the furnace is required to be ≤0.003%, and the temperature of the molten iron entering the furnace is ≥1350°C. The method of converter smelting is: the top and bottom double-blowing converter is used for smelting, and the steel tapping temperature is required to be ≥1620°C. During the steel tapping process, preliminary composition formulation and deoxidation alloying operations are performed according to the chemical composition requirements. The method of refining in the LF refining furnace is: the LF furnace is used for refining, slag deoxidation and accurate proportioning of alloy components, and the basicity of the refined slag is required to be controlled at 3-8, and the refining end temperature is ≥1500°C. The method of RH vacuum treatment is: the RH furnace is used for vacuum degassing treatment, and the vacuum treatment time is required to be ≥30 minutes, and the temperature of the molten steel after vacuum treatment is ≥1500°C. The high-speed wire rolling method is as follows: after the billet is heated by a heating furnace, it is rolled through a rough rolling unit, an intermediate rolling unit, a pre-finishing rolling unit, a finishing rolling unit, a sizing unit, a laying head, an air cooling line, and a coiling station.

[0033] The bearing steel molten steel prepared by the converter and LF refining furnace is composed of the following components in weight percentage: C 1.05%, Si 0.15%, Mn 0.25%, P 0.008%, S 0.001%, Ni 0.10%, Cr 1.65%, Cu 0.10%, Al 0.030%, Ti 0.0020%, and the balance Fe and inevitable impurities.

[0034] The casting is carried out by a 6-machine 6-stream 200*200mm continuous casting machine. After the large reduction process of 25mm, five sets of reduction rollers are used to control the reduction according to the reduction of 3.0mm-3.0mm-6.0mm-8.0mm-5.0mm to produce qualified ingots.

[0035] After the ingot is slowly cooled for 36 hours, it is put into the furnace for rolling. The heating furnace adopts a three-stage heating process, with the preheating section temperature set at 880°C, the heating section temperature at 1050°C, and the soaking section temperature at 1225°C. The soaking section is kept warm for 1.5 hours before rolling. The rough rolling is carried out using a large compression ratio 1# rolling mill, and finally rolled into a φ6.5mm specification wire rod. The hydrochloric acid concentration (hydrochloric acid: water = 1:1), hydrochloric acid temperature of 75°C, and pickling time of 30 minutes are used for testing. Figure 3 As shown, there are no corrosion pits on the end face of the wire rod, and the acid corrosion resistance is significantly improved.

[0036] Comparative Example

[0037] This embodiment provides a production method for improving the acid corrosion resistance of bearing steel wire.

[0038] The production method comprises the following steps in sequence: molten iron pretreatment→converter smelting→LF refining furnace refining→RH vacuum treatment→continuous casting→heating in a heating furnace→high-speed wire rolling→finished wire rod.

[0039] The bearing steel molten steel prepared by the converter and LF refining furnace is composed of the following components in weight percentage: C 0.96%, Si 0.24%, Mn 0.28%, P 0.020%, S 0.008%, Ni 0.02%, Cr 1.45%, Cu 0.03%, Al 0.015%, Ti 0.0023%, and the balance Fe and inevitable impurities.

[0040] The casting is carried out by a 6-machine 6-stream 180*240mm continuous casting machine, and the reduction amount is 13mm. The five groups of reduction rollers are controlled according to the reduction amount of 1.0mm-3.0mm-3.0mm-5.0mm-1.0mm to produce qualified casting billets.

[0041] After the ingot is slowly cooled for 36 hours, it is put into the furnace for rolling. The heating furnace adopts a three-stage heating process, with the preheating section temperature set at 800°C, the heating section temperature at 1100°C, the soaking section temperature at 1230°C, and the soaking section temperature holding time at 1.2-1.5 hours before rolling. The ordinary compression ratio 1# rolling mill is used for rough rolling, and the final rolling is φ10mm specification wire. The hydrochloric acid concentration (hydrochloric acid: water = 1:1), hydrochloric acid temperature of 75°C, and pickling time of 30 minutes are used for testing. Figure 4 As shown, there are obvious corrosion pits on the end face of the wire rod, and the acid corrosion resistance is poor.

[0042] The above description is only a preferred embodiment of the present invention and does not limit the present invention in other forms. Any technician familiar with the profession may use the technical content disclosed above to change or modify it into an equivalent embodiment with equivalent changes and apply it to other fields. However, any simple modification, equivalent change and modification made to the above embodiment based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A production method for improving the acid corrosion resistance of bearing steel wire, the process of the method is: molten iron pretreatment → converter smelting → LF refining furnace refining → RH vacuum treatment → continuous casting → heating furnace heating → high-speed wire rolling → finished wire, characterized in that: The bearing steel molten steel prepared by the converter and LF refining furnace is composed of the following components in weight percentage: C 0.95-1.05%, Si 0.15-0.35%, Mn 0.25-0.45%, P 0.008-0.015%, S 0.001-0.005%, Ni 0.10-0.30%, Cr 1.40-1.65%, Cu 0.10-0.30%, Al 0.01-0.03%, Ti 0.001~0.002%, the balance is Fe and inevitable impurities; in the continuous casting production process, a large reduction mode is adopted for production, and five groups of reduction rollers are used for reduction, and the specific reduction is 3.0mm-3.0mm-6.0mm-8.0mm-5.0mm; after the continuous casting process, the ingot enters the heating furnace after slow cooling, and the heating furnace adopts a three-stage heating process, the preheating section temperature setting value is 750-880℃, the heating section temperature is 1000-1100℃, the soaking section temperature is 1200-1250℃, and the soaking section insulation time is 1.2-1.5 hours before rolling.

2. The production method for improving the acid corrosion resistance of bearing steel wire according to claim 1, characterized in that: The pressure value of the continuous casting process varies due to different reduction amounts, and the fluctuation range is 2MPa to 13MPa.

3. The production method for improving the acid corrosion resistance of bearing steel wire according to claim 1, characterized in that: The method for pre-treating the molten iron is as follows: the molten iron is desulfurized by the KR method before entering the furnace, and the sulfur content of the molten iron entering the furnace is required to be ≤0.003%, and the temperature of the molten iron entering the furnace is required to be ≥1350°C.

4. The production method for improving the acid corrosion resistance of bearing steel wire according to claim 1, characterized in that: The converter smelting method is: using a top and bottom combined blowing converter for smelting, requiring the steel tapping temperature to be ≥1620°C, and performing preliminary component preparation and deoxidation and alloying operations according to the chemical composition requirements during the steel tapping process.

5. The production method for improving the acid corrosion resistance of bearing steel wire according to claim 1, characterized in that: The refining method of LF refining furnace is: using LF furnace for refining, slag deoxidation and accurate proportioning of alloy components, requiring the basicity of refining slag to be controlled at 3-8, and the refining end temperature ≥1500℃.

6. The production method for improving the acid corrosion resistance of bearing steel wire according to claim 1, characterized in that: The RH vacuum treatment method is: using an RH furnace for vacuum degassing treatment, requiring the vacuum treatment time to be ≥30 minutes, and the temperature of the molten steel after the vacuum treatment to be ≥1500°C.

7. The method for improving the acid corrosion resistance of bearing steel wire according to claim 1, characterized in that: The high-speed wire rolling method is as follows: after the billet is heated by a heating furnace, it is rolled through a rough rolling unit, an intermediate rolling unit, a pre-finishing rolling unit, a finishing rolling unit, a sizing unit, a laying head, an air cooling line, and a coiling station.

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