Stainless steel material, preparation method thereof and shaft sleeve

Abstract

The invention provides a stainless steel material, a preparation method of the stainless steel material and a shaft sleeve. The stainless steel material comprises, by mass, 0.02%-0.2% of carbon, 0.5%-2.0% of silicon, 0.5%-2.0% of manganese, 10%-20% of chromium, 3%-10% of nickel, 0.5%-5% of copper, 0.1%-2% of niobium and the balance iron and inevitable impurities. The high-hardness stainless steel material with excellent weldability, corrosion resistance and annealing softening resistance is obtained through multi-element composite strengthening and structure regulation and control, and the high-hardness stainless steel material is particularly suitable for manufacturing high-strength structural parts needing to be subjected to post-welding stress relief annealing or serving in the medium-high-temperature environment.

Description

Technical Field

[0001] This application belongs to the field of alloy materials technology, and relates to a stainless steel material, its preparation method, and a bushing. Background Technology

[0002] As a key basic component in the transmission and support system of pump equipment, the bushing is widely used in the core areas of centrifugal pumps, plunger pumps, slurry pumps and various industrial process pumps. Its core functions are to accurately support the pump shaft, maintain the concentricity of the rotor system, isolate the conveyed medium, and reduce friction and wear in key parts, so as to ensure the smooth operation, reliable sealing and long-term effectiveness of the entire pump set.

[0003] In actual service, the bushing must withstand the complex alternating stress caused by the high-speed rotation of the pump shaft, the abrasion and chemical corrosion of the conveyed medium (containing solid particles, corrosive or high-temperature and high-pressure media), and the periodic impact loads caused by misalignment or hydraulic pulsation. Under some extreme conditions, the bushing must also work reliably in harsh media environments such as high-temperature hot oil, high-speed flue gas, or abrasive slurry. At the same time, in order to meet the assembly accuracy, wear resistance, and anti-galling requirements of the pump shaft system, the bushing is often made of wear-resistant alloy, surface-hardened material, or wear-resistant alloy layer overlay / laser cladding. After welding, stress-relieving annealing treatment is required to eliminate residual welding stress and prevent deformation, cracking, or premature failure caused by stress concentration during long-term operation.

[0004] Chinese patent CN120967241A discloses a duplex stainless steel material, its preparation method, and its application. This method involves precisely controlling the chemical composition of the duplex stainless steel and rapidly immersing cold-rolled steel in water after heat treatment at 1050–1140°C to lower the surface temperature to below 120°C. This process effectively promotes the formation of a stable and uniform duplex structure in the steel. The hardness of the described stainless steel material is 28.3 HRC to 29.1 HRC.

[0005] Chinese patent CN120268996A discloses a preparation process and application of high-carbon 17-4PH stainless steel powder. By adding high-carbon ferrochrome, the carbon content in the material is increased, thereby improving the application performance of 17-4 stainless steel in terms of hardness and strength, so as to meet the needs of manufacturing parts with higher hardness, strength and wear resistance, while maintaining a certain degree of corrosion resistance.

[0006] Although the stainless steel material produced by the above method has a certain degree of corrosion resistance, it has low hardness, and its hardness will further decrease when annealed at high temperature of 550℃. It also has poor weldability and poor performance when applied to bushings. Summary of the Invention

[0007] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0008] This application provides a stainless steel material, its preparation method, and a bushing. Through multi-element composite strengthening and microstructure control, this application obtains a high-hardness stainless steel material with excellent weldability, corrosion resistance, and resistance to annealing softening. It is particularly suitable for manufacturing high-strength structural components that require post-weld stress-relief annealing or service in medium-high temperature environments.

[0009] In a first aspect, this application provides a stainless steel material, the composition of which, by mass percentage, includes: carbon of 0.02% to 0.2%, for example: 0.02%, 0.05%, 0.1%, 0.15%, or 0.2%, etc., not limited to the listed values, and other unlisted values ​​within this range also apply; silicon of 0.5% to 2.0%, for example: 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, or 2.0%, etc., not limited to the listed values, and other unlisted values ​​within this range also apply; manganese of 0.5% to 2.0%, for example: 0.5%, 0.8%, 1%, 1.2%, 1.5%, 1.8%, or 2.0%, etc., not limited to the listed values, and other unlisted values ​​within this range also apply. Applicable; Chromium is 10% to 20%, for example: 10%, 12%, 15%, 18% or 20%, etc., not limited to the listed values, and other unlisted values ​​within this range also apply; Nickel is 3% to 10%, for example: 3%, 6%, 7%, 8%, 9% or 10%, etc., not limited to the listed values, and other unlisted values ​​within this range also apply; Copper is 0.5% to 5%, for example: 0.5%, 1%, 2%, 3%, 4% or 5%, etc., not limited to the listed values, and other unlisted values ​​within this range also apply; Niobium is 0.1% to 2%, for example: 0.1%, 0.5%, 1%, 1.5% or 2%, etc., not limited to the listed values, and other unlisted values ​​within this range also apply, with the remainder being iron and unavoidable impurities.

[0010] In the stainless steel material described in this application, Cu has high solid solubility in high-temperature austenite but extremely low solid solubility in low-temperature martensite. Through heat treatment, supersaturated Cu atoms precipitate out of the martensitic matrix as extremely fine, coherent Cu-rich phases (approximately several to tens of nanometers in size). These nanoscale precipitates effectively hinder dislocation movement, producing a strong strengthening effect and significantly improving the material's hardness and strength. Nb is a strong carbide-forming element; Nb forms extremely fine, dispersed NbC precipitates with C. These NbC precipitates exhibit extremely high thermal stability at high temperatures. Nb can fix carbon atoms, preventing the formation of coarse chromium carbides during heat treatment, thereby ensuring the chromium content in the matrix. Copper and NbC precipitates together constitute a dual-precipitate strengthening system, making the strengthening effect more uniform and stable. Combined with the effects of silicon, manganese, nickel, and other elements, the material's hardness is significantly improved, and the stable precipitates allow the material to maintain high hardness even at high temperatures. The high chromium content in the stainless steel material allows for the formation of a dense and stable Cr2O3 passivation film on the material surface, giving the stainless steel excellent oxidation resistance and acid and alkali corrosion resistance. The low carbon content in the stainless steel material significantly reduces the tendency for hard and brittle martensite to form in the weld heat-affected zone and for intergranular corrosion. Nb can fix carbon, inhibiting the formation of harmful chromium carbides during welding thermal cycling, reducing intergranular corrosion sensitivity and embrittlement tendency, and improving the weldability of the material.

[0011] In one embodiment, the unavoidable impurities include sulfur and / or phosphorus.

[0012] In one embodiment, the mass fraction of sulfur and / or phosphorus is independently ≤0.04% based on 100% of the mass of the stainless steel material.

[0013] In one embodiment, the stainless steel material has a hardness ≥40HRC after high-temperature annealing at 550°C.

[0014] Secondly, this application provides a method for preparing stainless steel material as described in the first aspect, the method comprising the following steps:

[0015] After the first smelting of pure iron, low-carbon ferrochrome, nickel plate, electrolytic manganese, low-carbon ferrosilicon, and copper plate is carried out, ferroniobium is added for the second smelting to obtain molten steel.

[0016] After the molten steel is mixed with deoxidizing materials and deoxidized, it is tapped and poured to obtain a casting.

[0017] The stainless steel material is obtained by heat treatment of the casting.

[0018] In one embodiment, the temperature of the first melting is 1550℃ to 1600℃, for example: 1550℃, 1560℃, 1580℃, 1590℃ or 1600℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] In one embodiment, a slag-collecting agent is used for slag formation and cleaning during the first smelting process. After slag cleaning is completed, sample composition analysis and material replenishment are performed.

[0020] In one embodiment, the temperature of the second melting is 1600℃ to 1650℃, for example: 1600℃, 1610℃, 1620℃, 1630℃, 1640℃ or 1650℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] In one embodiment, when the molten steel is mixed with the deoxidizing material, the temperature of the molten steel is 1610℃~1640℃, for example: 1610℃, 1620℃, 1630℃ or 1640℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] In one embodiment, the deoxidizing material comprises a silicon-calcium alloy and / or a steel cleaner.

[0023] In one embodiment, based on the mass of the molten steel as 100%, the amount of deoxidizing material added is 0.1% to 0.5%, for example: 0.1%, 0.2%, 0.3%, 0.4% or 0.5%, etc., not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0024] In one embodiment, the heat treatment includes heating and heat preservation, and air cooling.

[0025] In one embodiment, the heating and heat preservation temperature is 1100℃~1120℃, for example: 1100℃, 1105℃, 1110℃, 1115℃ or 1120℃, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] In one embodiment, the heating and heat preservation time is 2h to 4h, for example: 2h, 2.5h, 3h, 3.5h or 4h, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] In one embodiment, the air-cooled temperature is 450°C to 550°C, for example: 450°C, 480°C, 500°C, 520°C or 550°C, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] In one embodiment, the air cooling time is 2h to 4h, for example: 2h, 2.5h, 3h, 3.5h or 4h, etc., and is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0029] Thirdly, this application provides a bushing comprising the stainless steel material as described in the first aspect.

[0030] During use, the base material of the bushing is subject to corrosion by the medium and abrasion by solid particles / pump shaft, which leads to increased clearance, intensified vibration, and failure. In the process of hard alloy layer overlay / laser cladding of the bushing, preheating and post-weld annealing are required, which will reduce the hardness and wear resistance of the base material. The stainless steel material described in this application has excellent corrosion resistance, weldability, and resistance to annealing softening. When used as a bushing, it can improve the structural stability of the bushing and maintain high hardness and wear resistance after post-weld annealing, thus significantly improving the service life of the bushing.

[0031] The numerical range described in this application includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific point values ​​included in the range.

[0032] Compared with related technologies, this application has the following advantages:

[0033] (1) The stainless steel material described in this application has excellent corrosion resistance, weldability and annealing softening resistance, and is particularly suitable for manufacturing high-strength structural parts that require post-weld stress relief annealing or service in medium-high temperature environments.

[0034] (2) The stainless steel material described in this application can reach a hardness of 41.2 HRC or above after high-temperature annealing at 550℃, and has excellent weldability, with no cracks or internal defects after welding.

[0035] After reading and understanding the detailed description, other aspects can be understood. Detailed Implementation

[0036] The technical solution of this application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely to help understand this application and should not be regarded as specific limitations on this application.

[0037] Example 1

[0038] This embodiment provides a stainless steel material, the composition of which, by mass percentage, includes: 0.1% carbon, 1.3% silicon, 1.3% manganese, 15% chromium, 7% nickel, 2.5% copper, 0.8% niobium, 0.01% sulfur, 0.01% phosphorus, and the remainder being iron.

[0039] The stainless steel material is obtained by the following method:

[0040] Pure iron, low-carbon ferrochrome, nickel plate, electrolytic manganese, low-carbon ferrosilicon, and copper plate are added to the smelting furnace in sequence. After checking that the equipment is in good condition, the furnace is energized and smelted until the furnace charge is completely melted. Slag-forming operations are repeatedly performed using slag-collecting agent. After slag removal, the temperature is measured and the first smelting treatment is carried out at 1600℃. The materials are replenished according to the control composition and standard composition on the batching list. Niobium iron is added and the second smelting is carried out at 1610℃ to obtain molten steel.

[0041] After deoxidizing the molten steel at a temperature of 1610℃, it is mixed with 0.3% of the molten steel mass of deoxidizing material (silicon-calcium alloy and steel cleaner, mass ratio of 3:7) for deoxidation treatment, and then the steel is tapped and poured to obtain castings.

[0042] The casting was heated to 1110℃ at a heating rate of 5℃ / min and held at that temperature for 3 hours, then air-cooled at 500℃ for 3 hours to obtain the stainless steel material.

[0043] Example 2

[0044] This embodiment provides a stainless steel material, the composition of which, by mass percentage, includes: 0.02% carbon, 0.5% silicon, 0.5% manganese, 10% chromium, 5% nickel, 0.5% copper, 0.1% niobium, 0.02% sulfur, 0.02% phosphorus, and the remainder being iron.

[0045] The stainless steel material is obtained by the following method:

[0046] Pure iron, low-carbon ferrochrome, nickel plate, electrolytic manganese, low-carbon ferrosilicon, and copper plate are added to the smelting furnace in sequence. After checking that the equipment is in good condition, the furnace is energized and smelted until the furnace charge is completely melted. Slag-forming operations are repeatedly performed using slag-collecting agent. After slag removal, the temperature is measured, and the first smelting treatment is carried out at 1550℃. The materials are replenished according to the control composition and standard composition on the batching list. Niobium iron is added, and the second smelting is carried out at 1600℃ to obtain molten steel.

[0047] After deoxidizing the molten steel at a temperature of 1605℃, it is mixed with 0.1% of the molten steel mass of deoxidizing material (silicon-calcium alloy and steel cleaner, mass ratio of 2:8) for deoxidation treatment, and then the steel is tapped and poured to obtain castings.

[0048] The casting was heated to 1115℃ at a heating rate of 5℃ / min and held at that temperature for 4 hours, then air-cooled at 450℃ for 4 hours to obtain the stainless steel material.

[0049] Example 3

[0050] This embodiment provides a stainless steel material, the composition of which, by mass percentage, includes: 0.2% carbon, 2.0% silicon, 2.0% manganese, 20% chromium, 10% nickel, 5% copper, 2% niobium, 0.01% sulfur, 0.01% phosphorus, and the remainder being iron.

[0051] The stainless steel material is obtained by the following method:

[0052] Pure iron, low-carbon ferrochrome, nickel plate, electrolytic manganese, low-carbon ferrosilicon, and copper plate are added to the smelting furnace in sequence. After checking that the equipment is in good condition, the furnace is energized and smelted until the furnace charge is completely melted. Slag-forming operations are repeatedly performed using slag-collecting agent. After slag removal, the temperature is measured and the first smelting treatment is carried out at 1600℃. The materials are replenished according to the control composition and standard composition on the batching sheet. Niobium iron is added and the second smelting is carried out at 1620℃ to obtain molten steel.

[0053] After deoxidizing the molten steel at a temperature of 1615℃, it is mixed with 0.5% of the molten steel mass of deoxidizing material (silicon-calcium alloy and steel cleaner, mass ratio of 4:6) for deoxidation treatment, and then the steel is tapped and poured to obtain castings.

[0054] The casting was heated to 1120℃ at a heating rate of 5℃ / min and held at that temperature for 2 hours, then air-cooled at 550℃ for 2 hours to obtain the stainless steel material.

[0055] Comparative Example 1

[0056] The only difference between this comparative example and Example 1 is that the niobium content is 0.05%, while the other conditions and parameters are exactly the same as in Example 1.

[0057] Comparative Example 2

[0058] The only difference between this comparative example and Example 1 is that the niobium content is 3%, while the other conditions and parameters are exactly the same as in Example 1.

[0059] Comparative Example 3

[0060] The only difference between this comparative example and Example 1 is that the chromium content is 5%, while the other conditions and parameters are exactly the same as in Example 1.

[0061] Comparative Example 4

[0062] The only difference between this comparative example and Example 1 is that the chromium content is 25%, while the other conditions and parameters are exactly the same as in Example 1.

[0063] Comparative Example 5

[0064] This comparative example uses commercially available 17-4PH stainless steel.

[0065] Performance testing:

[0066] (1) Hardness test of 550℃ high temperature annealing: After the casting is kept at 550℃ for 2 hours, it is cooled with the furnace. The oxide scale on the surface is removed, and the surface is polished until the surface roughness is better than Ra1.6. Rockwell hardness test is performed (test five different positions, take the average value, and record the difference between the maximum and minimum values).

[0067] (2) The sample is processed into a flat plate and a beveled Y-shaped sample, welded, and the crack condition is inspected by penetrant testing and internal defects are detected by X-ray.

[0068] The test results are shown in Table 1:

[0069] Table 1

[0070] As can be seen from Table 1, as obtained from Examples 1-3, the stainless steel material described in this application can achieve a hardness of over 41.2 HRC after high-temperature annealing at 550℃, and has excellent weldability, with no cracks or internal defects after welding.

[0071] As can be seen from the comparison between Example 1 and Comparative Examples 1-2, the niobium content in the stainless steel material described in this application affects its performance. When the niobium content in the stainless steel material is controlled at 0.1% to 2%, the stainless steel material has better performance. If the niobium content in the stainless steel material is too low, too little Nb cannot effectively "fix" carbon atoms, and the high-temperature hardness of the material decreases sharply. If niobium is a strong ferrite-forming element in the stainless steel material, if the niobium content is too high, it will change the phase balance of the weld metal, increase the risk of embrittlement of the weld heat-affected zone, significantly reduce the weldability of the material, and increase the risk of cracking.

[0072] As can be seen from the comparison between Example 1 and Comparative Examples 3-4, the chromium content in the stainless steel material described in this application affects its performance. When the chromium content in the stainless steel material is controlled at 10% to 20%, the stainless steel material has better performance. If the chromium content in the stainless steel material is too low, an effective Cr2O3 passivation film cannot be formed, and the corrosion resistance of the material will decrease significantly. If the chromium content in the stainless steel material is too high, it will increase the tendency for solidification cracking, and the high-temperature hardness of the material will decrease significantly.

[0073] As can be seen from the comparison between Example 1 and Comparative Example 5, the stainless steel material described in this application has a significantly improved hardness during high-temperature annealing compared to commercially available conventional precipitation-hardening 17-4PH stainless steel.

Claims

1. A stainless steel material, wherein, The stainless steel material comprises, by mass percentage: 0.02%–0.2% carbon, 0.5%–2.0% silicon, 0.5%–2.0% manganese, 10%–20% chromium, 3%–10% nickel, 0.5%–5% copper, 0.1%–2% niobium, with the remainder being iron and unavoidable impurities.

2. The stainless steel material as described in claim 1, wherein, The unavoidable impurities include sulfur and / or phosphorus; Optionally, the mass fraction of sulfur and / or phosphorus is independently ≤0.04% based on 100% of the mass of the stainless steel material.

3. The stainless steel material as described in claim 1 or 2, wherein, The stainless steel material has a hardness ≥40HRC after high-temperature annealing at 550℃.

4. A method for preparing the stainless steel material as described in any one of claims 1-3, comprising the following steps: After the first smelting of pure iron, low-carbon ferrochrome, nickel plate, electrolytic manganese, low-carbon ferrosilicon, and copper plate is carried out, ferroniobium is added for the second smelting to obtain molten steel. After the molten steel is mixed with deoxidizing materials and deoxidized, it is tapped and poured to obtain a casting. The stainless steel material is obtained by heat treatment of the casting.

5. The preparation method according to claim 4, wherein, The temperature of the first melting is 1550℃~1600℃; Optionally, during the first smelting process, a slag-collecting agent is used for slag formation and cleaning. After the slag cleaning is completed, sample composition analysis and material replenishment are performed.

6. The preparation method according to claim 4 or 5, wherein, The second melting temperature is 1600℃~1650℃.

7. The preparation method according to any one of claims 4-6, wherein, When the molten steel is mixed with the deoxidizing material, the temperature of the molten steel is 1610℃~1640℃.

8. The preparation method according to any one of claims 4-7, wherein, The deoxidizing material includes silicon-calcium alloy and / or steel cleaning agent; Optionally, the amount of deoxidizing material added is 0.1% to 0.5% based on 100% of the mass of the molten steel.

9. The preparation method according to any one of claims 4-8, wherein, The heat treatment includes heating and heat preservation, and air cooling; Optionally, the heating and heat preservation temperature is 1110℃~1120℃; Optionally, the heating and heat preservation time is 2 hours to 4 hours; Optionally, the temperature of the air cooler is 450℃~550℃; Optionally, the air cooling time is 2h to 4h.

10. A bushing, wherein, The bushing comprises the stainless steel material as described in any one of claims 1-3.

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