Wear-resistant austenitic stainless steel roller and preparation method thereof

Abstract

The invention discloses a wear-resistant austenitic stainless steel roller and a preparation method thereof, and belongs to the technical field of roller machining.The preparation method comprises the following steps that outer-layer molten steel, middle-layer molten steel and core-layer molten steel are sequentially poured into a roller forming mold for centrifugal casting, and a roller pouring body is prepared; after a roller casting body is prepared by optimizing the element composition of molten steel, the roller casting body is austenitized and carburized, and a layer of alloy powder is cladded outside the roller casting body, so that the wear resistance and corrosion resistance of the stainless steel roller are effectively improved, and the tensile property and impact strength of the stainless steel roller are also improved.

Description

Technical Field

[0001] The invention relates to the technical field of roller processing, and in particular to a wear-resistant austenitic stainless steel roller and a preparation method thereof. Background Art

[0002] Rollers are key components of rolling mill equipment and are widely used in the rolling process in metallurgical and non-metallurgical fields. With the development of modern industry, especially the automotive and machinery industries, the requirements for the dimensional accuracy, surface quality and performance of steel are constantly improving, and more stringent requirements are also put forward for the manufacturing and processing technology of rolls.

[0003] The prior art, a Chinese invention patent with publication number CN111136246A, provides a method for preparing a high-speed steel roll, comprising the following steps: separately smelting high-speed molten steel for the outer layer of the roll, molten semi-steel for the middle layer and molten iron for the core, and sequentially casting the outer layer, middle layer and core of the roll, taking out and cooling to room temperature 24-48 hours after the casting of the high-speed steel roll ingot is completed, performing rough machining, quenching and secondary tempering treatment and fine machining to obtain a high-speed steel roll, effectively improving the morphology and distribution of carbides in the solidified structure of the high-speed steel, obtaining a large number of fine, uniform and dispersed MC carbides on the outer layer matrix of the roll, reducing the segregation of alloy elements, and comprehensively improving the comprehensive mechanical properties of the roll.

[0004] In the prior art, the wear resistance of the rolling mill is mainly improved by improving the process and increasing the precipitation of secondary carbides in the outer layer of the rolling mill. However, the precipitation of carbides is often accompanied by a decrease in the toughness of the matrix. If the carbides precipitate too much or are improperly distributed, the rolling mill will suffer brittle fracture when subjected to greater stress, thereby reducing the mechanical strength of the rolling mill and shortening the service life of the rolling mill.

[0005] In view of the technical defects in this aspect, a solution is now proposed. Summary of the invention

[0006] The object of the present invention is to provide a wear-resistant austenitic stainless steel roller and a preparation method thereof, so as to solve the technical problem in the prior art that the mechanical properties of the stainless steel roller are reduced while the wear resistance of the stainless steel roller is increased by increasing the content of secondary carbides precipitated in the outer layer structure of the roller, resulting in that both the mechanical properties and the wear resistance of the stainless steel roller need to be further improved.

[0007] The object of the present invention can be achieved by the following technical scheme: A method for preparing a wear-resistant austenitic stainless steel roll comprises the following steps:

[0008] S1. Pour the outer layer molten steel, middle layer molten steel, and core layer molten steel into the roll forming die in sequence for centrifugal casting to obtain a roll casting body, and then reprocess the roll casting body to obtain a roll blank;

[0009] S2. Perform carburizing treatment on the surface of the roll blank to obtain a carburized roll;

[0010] S3. Laser clad a wear-resistant layer on the surface of the carburized roll to obtain a stainless steel roll.

[0011] Further, in step S1, the outer layer molten steel includes the following components by weight percentage: Mn 8-12%, Cr 14-17%, Mo 1.8-2.3%, C 1.3-1.6%, Si 0.5-1.6%, Ni 5-7%, B 0.1-0.5%, SiC 0.8-1.2%, Zr 0.6-0.8%, Ba 0.02-0.05%, Ce 0.01-0.04%, P≤0.05%, S≤0.03%, and the balance is Fe and trace inevitable elements; the middle layer molten steel includes the following components by weight percentage: C 2.8-3.2%, Si 1.5-1.8%, Mn 8-12%, Cr 14-17%, Mo 1.8-2.3%, Ni 0.5-1.0%, B 0.1-0.5%, Nd 0.02-0.05%, Ce 0.01-0.04%, P≤0.05%, S≤0.03%, and the balance is Fe and trace inevitable elements; the core layer molten steel includes the following components by weight percentage: C 3.5-3.8%, Cr 14-17%, Mn 1.1-1.4%, Mo 0.6-0.8%, Si 2.6-2.8%, Ni 2-3%, Sr 0.02-0.05%, V 0.01-0.04%, P≤0.05%, S≤0.03%, and the balance is Fe and trace inevitable elements.

[0012] Further, in step S1, the centrifugal casting includes the following steps:

[0013] A1. Raise the temperature of the roll forming die to 1500-1580°C, pour the outer layer molten steel into the roll forming die protected by nitrogen, after standing for degassing, slowly increase the rotational speed of the roll forming die to 1500-2000 r / min, centrifugally rotate for 8-10 min, and let the temperature of the roll forming die naturally cool to 1000-1100°C, and perform heat preservation treatment for 10-15 min to form the outer layer;

[0014] A2. The temperature of the roll forming die is raised to 1380 - 1430 °C, the roll forming die stops rotating, the middle layer of molten steel is poured into the roll forming die, after standing for degassing, the rotational speed of the roll forming die is slowly increased to 1500 - 2000 r / min, centrifugally rotated for 10 - 14 min, the roll forming die is naturally cooled to 900 - 1000 °C, heat-insulated for 10 - 15 min, and an intermediate layer is formed on the inner side of the outer layer;

[0015] A3. The temperature of the roll forming die is raised to 1300 - 1400 °C, the roll forming die stops rotating, the core layer of molten steel is poured into the roll forming die to fill the core layer of the intermediate layer, and the roll forming die is cooled to room temperature at a cooling rate of 20 - 30 °C / h to obtain a roll casting.

[0016] Further, in step S1, the reprocessing includes the following steps:

[0017] B1. According to the size requirements of the roll, the surface of the roll casting is successively rough-machined and finish-machined using a lathe to obtain a milled casting;

[0018] B2. The milled casting is placed in a heating furnace, and the heating furnace is heated to 950 - 1050 °C at a heating rate of 10 - 12 °C / s and held for 6 - 8 min to make it fully austenitized to obtain an austenitic casting;

[0019] B3. The austenitic casting is put into an annealing furnace, the austenitic casting is heated to 700 - 800 °C at a heating rate of 10 - 15 °C / s, heat-insulated for 40 - 60 min, the austenitic casting is cooled to room temperature at a rate of 15 - 20 °C / min, the austenitic casting is then heated to 500 - 550 °C at a heating rate of 10 - 15 °C / s, heat-insulated for 40 - 60 min, and the austenitic casting is cooled to room temperature at a rate of 8 - 10 °C / min to obtain a roll blank.

[0020] Further, the carburizing treatment in step S2 includes the following steps:

[0021] C1. After the surface of the roll blank is scrubbed with 0.5 mol / L sodium hydroxide solution, it is cleaned once with purified water and anhydrous ethanol to obtain a pretreated roll;

[0022] C2. The pretreated roll is put into a carburizing furnace for carburizing treatment to obtain a carburized roll.

[0023] Further, in step C2, the carburizing temperature is 480 - 500 °C, the carburizing atmosphere consists of carbon monoxide and nitrogen dioxide in a volume ratio of 5:1, and the carburizing time is 48 - 50 h.

[0024] Further, in step S3, the laser cladding includes the following steps:

[0025] D1. Coat a layer of adhesive on the surface of the carburized roll, and then use the adhesive as a bonding layer to adhere alloy powder to the carburized roll, forming a layer of alloy powder with a thickness of 2 - 3 mm on the surface of the carburized roll to obtain a coated roll;

[0026] D2. Use laser cladding to clad the alloy powder layer on the surface of the coated roll, forming a clad layer on the surface of the carburized roll to obtain an alloy clad roll;

[0027] D3. Polish the surface of the alloy clad roll with water sandpaper, and then perform mechanical polishing with polishing paste having a particle size of 1.5 - 2.5 to prepare a stainless steel roll.

[0028] Furthermore, in step D1, the adhesive is an epoxy resin adhesive; in step D2, the alloy powder is composed of 316 stainless steel powder, titanium carbide, boron carbide, nickel, molybdenum disulfide, silicon carbide, and graphite powder in a weight ratio of 75:8:4:2:3:7:1; in step D3, the conditions for laser cladding are: using a welding machine equipped with a laser cladding system, the working current is 150 A, the power is 2 - 3 kW, the tungsten electrode diameter is 2.5 - 3 mm, the laser spot diameter is 5 - 7 mm, the laser scanning rate is 5 - 7 mm / s, the shielding gas is argon, and the shielding gas flow rate is 4 - 6 L / s.

[0029] A wear-resistant austenitic stainless steel roll, which is processed according to a preparation method of a wear-resistant austenitic stainless steel roll

[0030] The present invention has the following beneficial effects:

[0031] 1. For the wear-resistant austenitic stainless steel roll of the present invention, by performing centrifugal casting in a nitrogen environment, a roll blank with a three-layer composite structure of an outer layer, a middle layer, and a core layer is formed. By sequentially performing carburizing treatment on the roll blank, the surface strength of the roll is improved. Then, a wear-resistant clad layer is formed on the surface of the roll by laser cladding to prepare a stainless steel roll. During the preparation process, by optimizing the elemental composition of the molten steel, the solubility of nitrogen in the molten steel is improved. Nitrogen can form nitrides with high hardness and strong toughness in the molten steel and serve as a solid solution strengthening element. When the roll casting body is subjected to high-temperature austenitization, the austenite structure is expanded and stabilized. Through annealing treatment, the stress agglomeration in the material is eliminated, making the internal structure of the material more uniform, thereby reducing the brittleness of the material and improving the toughness and plasticity of the roll blank. By cladding a layer of alloy powder coating on the surface of the carburized roll after carburizing treatment of the roll blank, a self-lubricating wear-resistant coating is formed on the surface of the stainless steel roll, improving the wear resistance of the stainless steel roll and simultaneously improving the mechanical strength of the material while improving the wear resistance of the material.

[0032] 2. In the process of manufacturing the wear-resistant austenitic stainless steel roll of the present invention, by optimizing the composition of the molten steel and adding metal elements such as manganese, chromium, and molybdenum to the molten steel, the organizational structure and properties of the steel are affected. In a nitrogen environment, the formed grains of the steel are refined, the nitrogen solubility of the steel is improved, and then the nitrogen content of the roll casting is increased. When nitrogen elements dissolve in the steel, they will occupy the lattice interstitial sites in the matrix metal or replace the atoms in the lattice, resulting in lattice distortion, increasing the internal stress field of the lattice, thereby hindering the movement of dislocations, improving the strength and hardness of the material. The nitrogen elements contained in the steel can form a layer of nitride film at the austenite grain boundaries, hindering the migration of grain boundaries and the recrystallization process, thus stabilizing the austenite structure. When subjected to external forces such as impact or tension, it can absorb more energy without breaking, showing higher toughness.

[0033] 3. For the wear-resistant austenitic stainless steel roll of the present invention, 316 stainless steel powder with good corrosion resistance is used as the main matrix material, and titanium carbide, boron carbide, and silicon carbide with high hardness and wear resistance are used to enhance the 316 stainless steel powder synergistically, improving its wear resistance and hardness. The lubricity and self-lubricity of molybdenum disulfide and graphite powder are combined, which helps to reduce the wear and friction coefficient of the material during the friction process and improve the wear resistance of the material. Nickel is combined synergistically with various elements to further optimize the wear resistance and mechanical properties of the cladding layer; by selecting a mixed gas composed of carbon monoxide and nitrogen dioxide as the carburizing gas source, at high temperatures, nitrogen dioxide decomposes into nitrogen and oxygen, which combines with reducing carbon monoxide to form a carburizing gas atmosphere. During the carburizing process, carbon monoxide reacts with metal oxides or other oxygen-containing substances, releasing metals or active carbon atoms. The active carbon atoms penetrate into the roll surface through diffusion, forming carbides inside the roll, increasing the hardness of the roll surface, providing a good hard support carrier for the cladding layer, and improving the overall hardness and impact resistance of the stainless steel roll. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0035] Figure 1 SEM photograph of the impact fracture of the stainless steel roll sample in Embodiment 1 of the present invention;

[0036] Figure 2 SEM photograph of the cross-section of the carburized roll in Embodiment 1 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0038] Embodiment 1

[0039] This embodiment provides a method for preparing a wear-resistant austenitic stainless steel roll, including the following steps:

[0040] S1. Prepare the roll casting

[0041] Raise the temperature of the roll forming die to 1500 °C, pour the outer layer molten steel into the roll forming die protected by nitrogen, after standing for degassing, slowly increase the rotation speed of the roll forming die to 1500 r / min, centrifugally rotate for 8 min, let the temperature of the roll forming die naturally drop to 1000 °C, and perform heat preservation treatment for 10 min to form the outer layer. Among them, the outer layer molten steel includes the following components by weight percentage: Mn 8%, Cr 14%, Mo 1.8%, C 1.3%, Si 0.5%, Ni 5%, B 0.1%, SiC 0.8%, Zr 0.6%, Ba 0.02%, Ce 0.01%, P 0.05%, S 0.03%, and the balance is Fe and trace inevitable elements;

[0042] Raise the temperature of the roll forming die to 1380 °C, stop the rotation of the roll forming die, pour the middle layer molten steel into the roll forming die, after standing for degassing, slowly increase the rotation speed of the roll forming die to 1500 r / min, centrifugally rotate for 10 min, let the temperature of the roll forming die naturally drop to 900 °C, and perform heat preservation treatment for 10 min to form the intermediate layer on the inner side of the outer layer. Among them, the middle layer molten steel includes the following components by weight percentage: C 2.8%, Si 1.5%, Mn 8%, Cr 14%, Mo 1.8%, Ni 0.5%, B 0.1%, Nd 0.02%, Ce 0.01%, P 0.05%, S 0.03%, and the balance is Fe and trace inevitable elements;

[0043] The temperature of the roll forming die rises to 1300 °C, the roll forming die stops rotating, the core layer molten steel is poured into the roll forming die to fill the core layer of the middle layer, and the roll forming die is cooled to room temperature at a cooling rate of 20 °C / h to obtain a roll casting body. Among them, the core layer molten steel includes the following components by weight percentage: C 3.5%, Cr 14%, Mn 1.1%, Mo 0.6%, Si 2.6%, Ni 2%, Sr 0.02%, V 0.01%, P 0.05%, S 0.03%, and the balance is Fe and trace inevitable elements. The thickness ratio of the outer layer, middle layer and core layer is 1:1.8:2, and the thickness of the outer layer is 80 mm.

[0044] S2. Preparation of roll blanks

[0045] According to the dimensional requirements of the roll, the surface of the roll casting body is successively rough machined and finish machined using a lathe to obtain a milled casting body;

[0046] The milled casting body is placed in a heating furnace, and the heating furnace is heated to 950 °C at a heating rate of 10 °C / s and held for 6 min to completely austenitize it to obtain an austenitic casting body;

[0047] The austenitic casting body is added to an annealing furnace. The austenitic casting body is heated to 700 °C at a heating rate of 10 °C / s and held for 40 min. The austenitic casting body is cooled to room temperature at a rate of 15 °C / min. The austenitic casting body is then heated to 500 °C at a heating rate of 10 °C / s and held for 40 min. The austenitic casting body is cooled to room temperature at a rate of 8 °C / min to obtain a roll blank.

[0048] S3. Preparation of carburized rolls

[0049] After the surface of the roll blank is scrubbed with 0.5 mol / L sodium hydroxide solution, it is cleaned once with purified water and absolute ethanol to obtain a pretreated roll;

[0050] The pretreated roll is placed in a carburizing furnace. Carbon monoxide and nitrogen dioxide are mixed in a volume ratio of 5:1 as the carrier gas and then introduced into the carburizing furnace. The temperature of the carburizing furnace is raised to 480 °C, and carburizing treatment is carried out for 48 h, then cooled and discharged to obtain a carburized roll.

[0051] S4. Preparation of stainless steel rolls

[0052] 316 stainless steel powder, titanium carbide, boron carbide, nickel, molybdenum disulfide, silicon carbide, and graphite powder are mixed evenly in a weight ratio of 75:8:4:2:3:7:1 to obtain alloy powder;

[0053] A layer of epoxy resin adhesive is coated on the surface of the carburized roll, and then alloy powder is adhered to the carburized roll with the epoxy resin adhesive as the bonding layer, forming a layer of alloy powder with a thickness of 2 - 3 mm on the surface of the carburized roll to obtain a coated roll;

[0054] A welding machine equipped with a laser cladding system is used, with a working current of 150 A, a power of 2 kW, a tungsten electrode diameter of 2.5 mm, a laser spot diameter of 5 mm, a laser scanning rate of 5 mm / s, argon as the shielding gas, and a shielding gas flow rate of 4 L / s. The coated roll is subjected to laser cladding to form a cladding layer on the surface of the carburized roll to obtain an alloy cladded roll;

[0055] The surface of the alloy cladded roll is polished successively with 150 - mesh, 320 - mesh, 400 - mesh, 600 - mesh, 800 - mesh, 1000 - mesh, 1200 - mesh, 1500 - mesh, and 2000 - mesh water - sandpapers, and then mechanically polished with a polishing paste with a particle size of 1.5 to prepare a stainless - steel roll.

[0056] Example 2

[0057] This example provides a method for preparing a wear - resistant austenitic stainless - steel roll, which includes the following steps:

[0058] S1. Prepare the roll casting body

[0059] The temperature of the roll - forming die is raised to 1540 °C, and the outer - layer molten steel is poured into the roll - forming die protected by nitrogen. After standing for degassing, the rotational speed of the roll - forming die is slowly increased to 1750 r / min, and it is centrifugally rotated for 9 min. The temperature of the roll - forming die naturally drops to 1050 °C and is heat - treated for 13 min to form the outer layer. Among them, the outer - layer molten steel includes the following components by weight percentage: Mn 10%, Cr 15%, Mo 2.0%, C 1.4%, Si 1.0%, Ni 6%, B 0.3%, SiC 1.0%, Zr 0.7%, Ba 0.04%, Ce 0.03%, P 0.03%, S 0.02%, and the balance is Fe and trace inevitable elements;

[0060] The temperature of the roll - forming die is raised to 1405 °C, the roll - forming die stops rotating, and the middle - layer molten steel is poured into the roll - forming die. After standing for degassing, the rotational speed of the roll - forming die is slowly increased to 1750 r / min, and it is centrifugally rotated for 12 min. The roll - forming die naturally drops to 950 °C and is heat - treated for 13 min to form the intermediate layer on the inner side of the outer layer. Among them, the middle - layer molten steel includes the following components by weight percentage: C 3.0%, Si 1.6%, Mn 10%, Cr 15%, Mo 2.1%, Ni 0.7%, B 0.3%, Nd 0.03%, Ce 0.03%, P 0.03%, S 0.02%, and the balance is Fe and trace inevitable elements;

[0061] The temperature of the roll forming die is raised to 1350 °C, the roll forming die stops rotating, the core layer molten steel is poured into the roll forming die to fill the core layer of the middle layer, and the roll forming die is cooled to room temperature at a cooling rate of 25 °C / h to obtain a roll casting. Among them, the core layer molten steel includes the following components by weight percentage: C 3.6%, Cr 16%, Mn 1.3%, Mo 0.7%, Si 2.7%, Ni 2.5%, Sr 0.04%, V 0.03%, P 0.03%, S 0.02%, and the balance is Fe and trace inevitable elements. The thickness ratio of the outer layer, middle layer and core layer is 1:2:2.5, and the thickness of the outer layer is 90 mm.

[0062] S2. Prepare the roll blank

[0063] According to the size requirements of the roll, the surface of the roll casting is successively rough machined and finish machined using a lathe to obtain a milled casting;

[0064] The milled casting is placed in a heating furnace, and the heating furnace is heated to 1000 °C at a heating rate of 11 °C / s and held for 7 min to make it fully austenitized to obtain an austenitic casting;

[0065] The austenitic casting is added to an annealing furnace. The austenitic casting is heated to 750 °C at a heating rate of 13 °C / s and held for 50 min. The austenitic casting is cooled to room temperature at a rate of 17 °C / min. The austenitic casting is then heated to 530 °C at a heating rate of 13 °C / s and held for 50 min. The austenitic casting is cooled to room temperature at a rate of 9 °C / min to obtain a roll blank.

[0066] S3. Prepare the carburized roll

[0067] After the surface of the roll blank is scrubbed with 0.5 mol / L sodium hydroxide solution, it is cleaned once with purified water and anhydrous ethanol to obtain a pretreated roll;

[0068] The pretreated roll is placed in a carburizing furnace. Carbon monoxide and nitrogen dioxide are mixed in a volume ratio of 5:1 as the carrier gas and then introduced into the carburizing furnace. The temperature of the carburizing furnace is raised to 490 °C, and carburizing treatment is carried out for 49 h, then cooled and discharged to obtain a carburized roll.

[0069] S4. Prepare the stainless steel roll

[0070] Mix 316 stainless steel powder, titanium carbide, boron carbide, nickel, molybdenum disulfide, silicon carbide, and graphite powder evenly according to the weight ratio of 75:8:4:2:3:7:1 to obtain alloy powder;

[0071] A layer of epoxy resin adhesive is coated on the surface of the carburized roll, and then alloy powder is adhered to the carburized roll with the epoxy resin adhesive as the bonding layer, forming a layer of alloy powder with a thickness of 2 - 3 mm on the surface of the carburized roll to obtain a coated roll;

[0072] A welding machine equipped with a laser cladding system is used, with a working current of 150 A, a power of 2.5 kW, a tungsten electrode diameter of 2.8 mm, a laser spot diameter of 6 mm, a laser scanning rate of 6 mm / s, argon as the shielding gas, and a shielding gas flow rate of 5 L / s. Laser cladding is carried out on the coated roll to form a cladding layer on the surface of the carburized roll, obtaining an alloy clad roll;

[0073] The surface of the alloy clad roll is polished successively with 150 - mesh, 320 - mesh, 400 - mesh, 600 - mesh, 800 - mesh, 1000 - mesh, 1200 - mesh, 1500 - mesh, and 2000 - mesh water - sandpapers, and then mechanically polished with polishing paste with a particle size of 2.0 to prepare a stainless - steel roll.

[0074] Example 3

[0075] This example provides a method for preparing a wear - resistant austenitic stainless - steel roll, which includes the following steps:

[0076] S1. Prepare a roll casting body

[0077] The temperature of the roll - forming die is raised to 1580 °C, and the outer - layer molten steel is poured into the roll - forming die protected by nitrogen. After standing and degassing, the rotation speed of the roll - forming die is slowly increased to 2000 r / min, centrifugally rotated for 10 min, and the temperature of the roll - forming die is naturally cooled to 1100 °C and heat - insulated for 15 min to form the outer layer. Among them, the outer - layer molten steel includes the following components by weight percentage: Mn 12%, Cr 17%, Mo 2.3%, C 1.6%, Si 1.6%, Ni 7%, B 0.5%, SiC 1.2%, Zr 0.8%, Ba 0.05%, Ce 0.04%, P 0.02%, S 0.01%, and the balance is Fe and trace inevitable elements;

[0078] The temperature of the roll forming die rises to 1430 °C, the roll forming die stops rotating, the middle layer molten steel is poured into the roll forming die, after standing for degassing, the rotational speed of the roll forming die slowly increases to 2000 r / min, centrifugally rotates for 14 min, the roll forming die naturally cools to 1000 °C, and is heat-insulated for 15 min, forming an intermediate layer on the inner side of the outer layer. Among them, the middle layer molten steel includes the following components by weight percentage: C 3.2%, Si 1.8%, Mn 12%, Cr 17%, Mo 2.3%, Ni 1.0%, B 0.5%, Nd 0.05%, Ce 0.04%, P 0.02%, S 0.01%, and the balance is Fe and trace inevitable elements;

[0079] The temperature of the roll forming die rises to 1400 °C, the roll forming die stops rotating, the core layer molten steel is poured into the roll forming die to fill the core layer of the intermediate layer, and the roll forming die is cooled to room temperature at a cooling rate of 30 °C / h to obtain a roll casting body. Among them, the core layer molten steel includes the following components by weight percentage: C 3.8%, Cr 17%, Mn 1.4%, Mo 0.8%, Si 2.8%, Ni 3%, Sr 00.05%, V 0.04%, P 0.02%, S 0.01%, and the balance is Fe and trace inevitable elements. The thickness ratio of the outer layer, middle layer and core layer is 1:2.2:3, and the thickness of the outer layer is 100 mm.

[0080] S2. Prepare the roll blank

[0081] According to the size requirements of the roll, the surface of the roll casting body is successively rough-machined and finish-machined using a lathe to obtain a milled casting;

[0082] The milled casting is placed in a heating furnace, and the heating furnace rises to 1050 °C at a heating rate of 12 °C / s and is heat-insulated for 8 min to completely austenitize it to obtain an austenitic casting;

[0083] The austenitic casting is added to an annealing furnace. The austenitic casting rises to 800 °C at a heating rate of 15 °C / s, is heat-insulated for 60 min, the austenitic casting is cooled to room temperature at a rate of 20 °C / min, the austenitic casting rises to 550 °C at a heating rate of 15 °C / s again, is heat-insulated for 60 min, and the austenitic casting is cooled to room temperature at a rate of 10 °C / min to obtain a roll blank.

[0084] S3. Prepare the carburized roll

[0085] After the roll blank is scrubbed with 0.5 mol / L sodium hydroxide solution on its surface, it is cleaned once with purified water and anhydrous ethanol to obtain a pretreated roll;

[0086] Put the pre-treated rolling roll into a carburizing furnace. Mix carbon monoxide and nitrogen dioxide in a volume ratio of 5:1 as the carrier gas and then introduce it into the carburizing furnace. Raise the temperature of the carburizing furnace to 500 °C, hold for carburizing treatment for 50 h, cool down, and discharge the material to obtain a carburized rolling roll.

[0087] S4. Prepare a stainless steel rolling roll

[0088] Mix 316 stainless steel powder, titanium carbide, boron carbide, nickel, molybdenum disulfide, silicon carbide, and graphite powder evenly according to a weight ratio of 75:8:4:2:3:7:1 to obtain alloy powder;

[0089] Coat a layer of epoxy resin adhesive on the surface of the carburized rolling roll, and then use the epoxy resin adhesive as the bonding layer to adhere the alloy powder to the carburized rolling roll, forming a layer of alloy powder layer with a thickness of 2 - 3 mm on the surface of the carburized rolling roll to obtain a coated rolling roll;

[0090] Use a welding machine equipped with a laser cladding system. The working current is 150 A, the power is 3 kW, the tungsten electrode diameter is 3 mm, the laser spot diameter is 7 mm, the laser scanning rate is 7 mm / s, the shielding gas is argon, and the shielding gas flow rate is 6 L / s. Carry out laser cladding on the coated rolling roll to form a cladding layer on the surface of the carburized rolling roll to obtain an alloy cladded rolling roll;

[0091] Successively use water sandpapers of 150 mesh, 320 mesh, 400 mesh, 600 mesh, 800 mesh, 1000 mesh, 1200 mesh, 1500 mesh, and 2000 mesh to polish the surface of the alloy cladded rolling roll, and then use polishing paste with a particle size of 2.5 for mechanical polishing to prepare a stainless steel rolling roll.

[0092] Comparative Example 1

[0093] The difference between this comparative example and Example 3 is that in step S1, silicon carbide is not added to the outer layer of molten steel, and the middle layer of molten steel includes the following components by weight percentage: C 3.2%, Si 1.8%, Mn 5%, Cr 12%, Mo 1%, Ni 1.0%, B 0.5%, Nd 0.05%, Ce 0.04%, P 0.02%, S 0.01%, and the balance is Fe and trace inevitable elements.

[0094] Comparative Example 2

[0095] The difference between this comparative example and Example 3 is that in step S1, argon is used as the shielding gas for the rolling roll forming die.

[0096] Comparative Example 3

[0097] The difference between this comparative example and Example 3 is that in step S3, the carrier gas of the carburizing furnace is carbon monoxide.

[0098] Comparative Example 4

[0099] The difference between this comparative example and Example 3 is that in step S4, no graphite powder was added to the alloy powder.

[0100] Performance test:

[0101] Referring to the standard GB / T 228.1-2021 "Metallic materials - Tensile testing - Part 1: Method of test at room temperature", the elongation and reduction of area of the stainless steel rolls prepared in Examples 1-3 and Comparative Examples 1-4 were tested;

[0102] Referring to the standard GB / T 229-2020 "Metallic materials - Charpy pendulum impact test method", the impact toughness of the stainless steel rolls prepared in Examples 1-3 and Comparative Examples 1-4 was tested;

[0103] Referring to the standard GB / T 12444-2006 "Metallic materials - Wear test method - Ring-on-block sliding wear test", the mass wear of the stainless steel rolls prepared in Examples 1-3 and Comparative Examples 1-4 was tested;

[0104] Referring to the standard GB / T 4334.6-2015 "Stainless steels - Method of ferric sulfate-sulfuric acid test", the corrosion rate of the stainless steel rolls prepared in Examples 1-3 and Comparative Examples 1-4 was tested;

[0105] The Brinell hardness of the stainless steel rolls prepared in Examples 1-3 and Comparative Examples 1-4 was tested using an HB-3000 Brinell hardness tester. The specific test results are shown in Table 1 below.

[0106] Table 1 - Data sheet for performance detection of specimens

[0107]

[0108]

[0109] Data analysis:

[0110] By comparing and analyzing the data in Table 1 above, the elongation of the stainless steel roll prepared by the present invention reaches 45.72%, the reduction of area reaches 52.05%, the impact toughness reaches 373.25 J / cm 2 , the mass wear is reduced to 12.1 mg, the corrosion rate is reduced to 28.01 g / (m 2 ·h), and the Brinell hardness reaches 136.27 HB. All performance parameters are superior to those of the comparative examples. Therefore, after optimizing the elemental composition of the molten steel to prepare the roll casting body, subjecting it to austenitization and carburizing treatment, and then cladding a layer of alloy powder on its exterior, the present invention not only effectively improves the wear resistance and corrosion resistance of the stainless steel roll, but also improves the tensile properties and impact strength of the stainless steel roll.

[0111] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only the specific embodiments. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A method for preparing a wear-resistant austenitic stainless steel roll, characterized in that: The following steps are involved: S1, pouring the outer layer molten steel, the middle layer molten steel and the core layer molten steel into a roll forming mold in sequence for centrifugal casting to prepare a roll casting body, and then reprocessing the roll casting body to prepare a roll blank; S2, performing carburizing treatment on the surface of the roll blank to prepare a carburized roll; S3. A wear-resistant layer is formed on the surface of the carburized roller by laser cladding to prepare a stainless steel roller.

2. The method for preparing a wear-resistant austenitic stainless steel roll according to claim 1, characterized in that: In step S1, the outer layer molten steel comprises the following components by weight percentage: Mn 8-12%, Cr 14-17%, Mo 1.8-2.3%, C 1.3-1.6%, Si 0.5-1.6%, Ni 5-7%, B 0.1-0.5%, SiC 0.8-1.2%, Zr 0.6-0.8%, Ba 0.02-0.05%, Ce 0.01-0.04%, P ≤ 0.05%, S ≤ 0.03%, the balance is Fe and trace amounts of inevitable elements; the middle layer molten steel comprises the following components by weight percentage: C 2.8-3.2%, Si 1.5-1.8%, Mn 8-12%, Cr 14-1 7%, Mo1.8-2.3%, Ni0.5-1.0%, B0.1-0.5%, Nd0.02-0.05%, Ce0.01-0.04%, P≤0.05%, S≤0.03%, the balance is Fe and trace amounts of inevitable elements; the core layer molten steel includes the following components by weight percentage: C3.5-3.8%, Cr14-17%, Mn1.1-1.4%, Mo0.6-0.8%, Si2.6-2.8%, Ni2-3%, Sr0.02-0.05%, V0.01-0.04%, P≤0.05%, S≤0.03%, the balance is Fe and trace amounts of inevitable elements.

3. The method for preparing a wear-resistant austenitic stainless steel roll according to claim 1, characterized in that: In step S1, centrifugal casting comprises the following steps: A1. The temperature of the roll forming mold is raised to 1500-1580°C, and the outer layer of molten steel is poured into the roll forming mold protected by nitrogen. After standing and degassing, the speed of the roll forming mold is slowly increased to 1500-2000r / min, and the centrifugal rotation is performed for 8-10min. The temperature of the roll forming mold is naturally cooled to 1000-1100°C, and the heat preservation treatment is performed for 10-15min to form the outer layer; A2. The temperature of the roll forming mold is raised to 1380-1430°C, the roll forming mold stops rotating, and the middle layer of molten steel is poured into the roll forming mold. After standing and degassing, the speed of the roll forming mold is slowly increased to 1500-2000r / min, and the roll forming mold is centrifugally rotated for 10-14min. The roll forming mold is naturally cooled to 900-1000°C, and the heat preservation treatment is carried out for 10-15min to form an intermediate layer on the inner side of the outer layer. A3. The temperature of the roll forming mold is raised to 1300-1400°C, the roll forming mold stops rotating, and core layer molten steel is poured into the roll forming mold to fill the core layer of the middle layer. The roll forming mold is cooled to room temperature at a cooling rate of 20-30°C / h to obtain a roll casting.

4. The method for preparing a wear-resistant austenitic stainless steel roll according to claim 1, characterized in that: In step S1, the reprocessing includes the following steps: B1. According to the size requirements of the roll, the surface of the roll casting is rough-machined and fine-machined in sequence using a lathe to obtain a milled casting; B2. Place the milled casting in a heating furnace, raise the temperature to 950-1050°C at a heating rate of 10-12°C / s, and keep the temperature for 6-8 minutes to completely austenitize the casting to obtain an austenitic casting; B3. Add the austenitic casting into an annealing furnace, heat the austenitic casting to 700-800°C at a heating rate of 10-15°C / s, keep the temperature for 40-60 minutes, cool the austenitic casting to room temperature at a rate of 15-20°C / min, heat the austenitic casting to 500-550°C at a heating rate of 10-15°C / s, keep the temperature for 40-60 minutes, cool the austenitic casting to room temperature at a rate of 8-10°C / min, and obtain a roll blank.

5. The method for preparing a wear-resistant austenitic stainless steel roll according to claim 1, characterized in that: The carburizing treatment in step S2 includes the following steps: C1. After scrubbing the surface of the roller blank with a 0.5 mol / L sodium hydroxide solution, the surface is cleaned once with purified water and anhydrous ethanol to obtain a pretreated roller; C2. Put the pretreated roll into a carburizing furnace for carburizing to prepare a carburized roll.

6. The method for preparing a wear-resistant austenitic stainless steel roll according to claim 5, characterized in that: In step C2, the carburizing temperature is 480-500° C., the carburizing atmosphere is composed of carbon monoxide and nitrogen dioxide in a volume ratio of 5:1, and the carburizing time is 48-50 hours.

7. The method for preparing a wear-resistant austenitic stainless steel roll according to claim 1, characterized in that: In step S3, laser cladding includes the following steps: D1. Coating a layer of adhesive on the surface of the carburizing roller, and then using the adhesive as a bonding layer to adhere the alloy powder to the carburizing roller, forming a layer of alloy powder with a thickness of 2-3 mm on the surface of the carburizing roller to obtain a coated roller; D2, cladding the alloy powder layer on the surface of the coated roller by laser cladding, forming a cladding layer on the surface of the carburized roller to obtain an alloy cladding roller; D3. Use water sandpaper to grind the surface of the alloy clad roller, and then use a polishing paste with a particle size of 1.5-2.5 for mechanical polishing to prepare a stainless steel roller.

8. The method for preparing a wear-resistant austenitic stainless steel roll according to claim 7, characterized in that: In step D1, the adhesive is an epoxy resin adhesive; in step D2, the alloy powder is composed of 316 stainless steel powder, titanium carbide, boron carbide, nickel, molybdenum disulfide, silicon carbide, and graphite powder in a weight ratio of 75:8:4:2:3:7:1; in step D3, the conditions for laser cladding are: a welding machine is equipped with a laser cladding system, the operating current is 150A, the power is 2-3kW, the tungsten electrode diameter is 2.5-3mm, the laser spot diameter is 5-7mm, the laser scanning rate is 5-7mm / s, the shielding gas is argon, and the shielding gas flow rate is 4-6L / s.

9. A wear-resistant austenitic stainless steel roller, characterized in that: The wear-resistant austenitic stainless steel roller is processed according to the preparation method of a wear-resistant austenitic stainless steel roller according to any one of claims 1-8.

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