Corrosion-resistant alloy die steel material and preparation method thereof

Abstract

The invention discloses a corrosion-resistant alloy die steel material and a preparation method thereof, belongs to the technical field of steel preparation, and aims to solve the technical problem that the corrosion resistance and toughness of alloy die steel in the prior art need to be further improved. The composite powder specifically comprises the following raw materials in parts by weight: 60 parts of nitrogen solid alloy powder, 20-25 parts of multiphase infiltration layer composite powder, 20-25 parts of metastable dispersion base powder and 50-60 parts of a dispersing agent, nitrogen solid alloy powder, multiphase infiltration layer composite powder, metastable dispersion base powder and graphene oxide are used as raw materials, the high-density alloy die steel is prepared through the working procedures of mixing, forming, hot isostatic pressing and heat treatment, solid solution and phase stabilization are achieved through the nitrogen solid alloy powder, a compact surface layer structure is formed through the multiphase infiltration layer composite powder, and the high-density alloy die steel is obtained. And the metastable dispersion base powder improves the structure uniformity, the graphene oxide improves interface bonding and load transfer, and finally the corrosion-resistant and high-toughness alloy die steel is prepared.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel production, in particular to a corrosion-resistant alloy die steel material and a preparation method thereof. BACKGROUND

[0002] In the long-term service, the conventional alloy die steel material often faces the combined action of corrosion medium, thermal cycle and mechanical load. With the complication of die working environment, the traditional corrosion-resistant alloy system mainly with Cr, Ni and Mo gradually develops towards multi-element combination. The corrosion resistance is improved through solid solution strengthening, dispersion strengthening and surface layer modification. In recent years, the research focuses on controlling the morphology of precipitated phase and the structure of grain boundary to form a stable passivation film and block the corrosion channel, so as to maintain the structural integrity in acid, alkali and high-temperature humid environment. At the same time, the development of alloy die steel changes from single element strengthening to microstructure regulation and interface structure optimization. Through refining the grain, stabilizing the metastable phase and constructing the distribution of multi-scale strengthening phase, the brittleness fracture risk can be reduced while maintaining high strength. Some research also introduces composite powder and gradient structure technology to balance the toughness of the matrix and the hardness of the surface layer, so as to meet the requirements of complex load and corrosion environment.

[0003] At present, the alloy die steel improves the corrosion resistance by increasing the content of corrosion-resistant elements such as Cr and Mo or using single surface layer infiltration treatment. However, when the alloy composition is high, the matrix is easy to generate coarse carbide or brittle phase, causing uneven structure and stress concentration. The material is prone to crack under stress or thermal shock. At the same time, the single layer or the dense infiltration layer is easy to peel off or be invaded by the medium along the interface in the high-temperature corrosion medium, and the surface layer protection gradually fails. The corrosion rate increases significantly with the service time, which is difficult to meet the long-term use requirements. Moreover, the conventional strengthening methods mainly focus on the improvement of strength and hardness, ignoring the stability of the interface and grain boundary. Therefore, the plasticity is insufficient under high strength, the distribution of strengthening phase is uneven, the grain boundary is discontinuous, and the phase scale is single, which makes the micro-cracks easily expand in tension and impact. In addition, the interface transition regulation of the powder system is limited in the process of forming, sintering and densification, which affects the overall reliability of the material under the combined action of high temperature and corrosion. SUMMARY

[0004] The present application aims to provide a corrosion-resistant alloy die steel material and a preparation method thereof, which can solve the technical problem that the corrosion resistance and toughness of the alloy die steel in the prior art need to be further improved.

[0005] The purpose of the present application can be achieved by the following technical solution: a corrosion-resistant alloy die steel material, comprising the following raw material components by weight: 60 parts of nitrogen solid alloy powder, 20-25 parts of multi-phase infiltration layer composite powder, 20-25 parts of metastable dispersion base powder and 50-60 parts of dispersing agent. The preparation method of the nitrogen solidified alloy powder comprises the following steps: A1, the ternary oxide complex is placed in a tube furnace, the tube furnace is heated to 800-820 DEG C under hydrogen atmosphere, the hydrogen flow is kept at 200 mL / min, and the tube furnace is naturally cooled to room temperature after reaction for 2 hours, and a ternary reduced alloy powder is obtained; A2, the ternary reduced alloy powder is transferred to a nitriding reaction kettle, ammonia is introduced, the temperature of the nitriding reaction kettle is increased to 700-720 DEG C, the ammonia decomposition rate is controlled, and the nitriding reaction kettle is naturally cooled to room temperature after reaction for 2 hours, and a nitrogen solidified alloy powder is obtained.

[0006] The principle for preparing the nitrogen solidified alloy powder is: The ternary oxide complex is reduced at high temperature in hydrogen atmosphere, Fe2O3, Cr2O3 and MoO3 are gradually reduced into corresponding metal state or suboxide, an Fe-Cr-Mo solid solution alloy matrix with high specific surface area and active sites is formed, then nitriding reaction is carried out in ammonia atmosphere, active nitrogen atoms generated by ammonia decomposition diffuse to the metal surface layer, and form stable metal nitrides or solid solution nitrogen phases with Fe, Cr and other elements, and a dispersed distribution of nitriding strengthening structure is constructed, and the synergistic effect of reduction and nitriding not only realizes oxygen-nitrogen conversion and interface purification, but also promotes the alloy powder to form a refined and uniform solid solution structure, thereby significantly improving the strength and stability of the subsequent alloy system.

[0007] Further, the dispersant is obtained by mixing tetraethyl orthosilicate, anhydrous ethanol and deionized water in a ratio of 8-10 mL:40-50 mL:10-12 mL; Further, in step A1, the heating rate of the tube furnace is 10 DEG C / min; in step A2, the heating rate of the nitriding reaction kettle is 8-12 DEG C / min, and the nitrogen decomposition rate is 20-25%.

[0008] Further, the preparation method of the ternary oxide complex comprises the following steps: B1, iron nitrate nonahydrate, chromium nitrate nonahydrate, ammonium molybdate and deionized water are added to a reaction kettle, after uniform stirring, citric acid and urea are added, the pH of the reaction system is adjusted to 6-7, and stirring is continued for 20-30 min to obtain a metal complex sol; B2, the metal complex sol is placed in a reaction kettle with a water bath temperature of 80-90 DEG C, and after heat preservation and standing until no liquid is produced, a ternary gel is obtained, the ternary gel is transferred to a muffle furnace with a temperature of 350 DEG C, heat preservation treatment is carried out for 50-60 min, after the treatment is completed, the muffle furnace is cooled to room temperature, the material is taken out, and grinding is carried out to obtain a ternary oxide complex.

[0009] The principle for preparing the ternary oxide complex is: Metal ions Fe3+ Cr 3+ and MoO4 2- The citric acid forms a stable organic complex under the action of citric acid, which acts as a complexing agent and carbon source, so that different metal ions are uniformly dispersed at the molecular scale. Urea is decomposed into ammonia and carbon dioxide under heating conditions, which can buffer the solution pH and promote the co-hydrolysis and gelation of metal ions. Subsequently, the organic complex is gradually decomposed and oxidized into corresponding Fe2O3, Cr2O3 and MoO3 during the heat treatment process. The three oxides are simultaneously nucleated, grown and formed into a dense interpenetrating structure in the gel skeleton, so that the ternary oxide composite obtained has uniform element distribution and stable multi-phase interface, which provides a good reaction basis for subsequent hydrogen reduction and alloying reaction.

[0010] Further, in step B1, the amount ratio of iron nitrate nonahydrate, chromium nitrate nonahydrate, ammonium molybdate tetrahydrate, deionized water, citric acid and urea is 1g:1.0-1.2g:0.2g:100mL:1.5g:0.8-1.0g; in step B2, the particle size of the ternary oxide composite is 20-30μm.

[0011] Further, the preparation method of the multi-phase interlayer composite powder comprises the following steps: C1, aluminum powder, aluminum chloride, sodium chloride, potassium chloride and silicon dioxide are put into a stainless steel reaction crucible, the stainless steel reaction crucible is placed under nitrogen protection, and then heated to 700°C and kept for 3-4h, and the aluminum-silicon co-permeation precursor is obtained after post-processing; C2, the aluminum-silicon co-permeation precursor, potassium carbonate and N,N-dimethylformamide are added to a high-temperature reaction kettle, and then nitrogen protection is performed after stirring uniformly, then boron trichloride gas is introduced, the gas flow rate is 30-50mL / min, the reaction kettle is heated to 880-920°C, and kept for 5-6h, and the multi-phase interlayer composite powder is obtained after post-processing.

[0012] The principle of preparing the multi-phase interlayer composite powder is: When the aluminum powder is heated together with aluminum chloride, sodium chloride and potassium chloride under nitrogen protection, halogenation activation occurs, and aluminum atoms are in the form of AlCl x Active species migrate and undergo aluminothermic reduction with silicon dioxide to form a dense attached Al-Si alloy interlayer skeleton, achieving uniform pre-dispersion of aluminum and silicon elements in the solid phase. Subsequently, boron trichloride is introduced into the high-temperature reaction kettle, and a stable solvent system is formed by potassium carbonate and N,N-dimethylformamide, which can capture chloride ions and promote the decomposition of BCl3 to produce active boron atoms. Active boron enters the surface layer of the Al-Si matrix to form fine and dispersed metal borides and silicon borides. Through the continuous reaction of "aluminum-silicon co-permeation-boriding", Al, Si and B are co-deposited on the surface of the particles and combined with the matrix, and finally a multi-phase interlayer composite powder with a multi-phase composite structure and a multi-element strengthening interface is obtained.

[0013] Further, in step C1, the ratio of aluminum powder, aluminum chloride, sodium chloride, potassium chloride and silicon dioxide is 8-10g:3-5g:40g:40g:2-3g. The post-processing includes: after the heat preservation is completed, the crucible is cooled to room temperature, the material is taken out and washed three times with anhydrous ethanol and deionized water respectively, and then dried in a vacuum drying oven at 80℃ to constant weight to obtain the aluminum-silicon co-diffusion precursor. Furthermore, in step C2, the ratio of aluminum-silicon co-diffusion precursor, potassium carbonate, and N,N-dimethylformamide is 8-10g:2g:180-200mL. The post-treatment includes: after the heat preservation is completed, the reaction vessel is cooled to room temperature, the reaction liquid is filtered to collect the filter cake, the filter cake is washed three times each with anhydrous ethanol and deionized water, and the filter cake is transferred to a vacuum drying oven at 80℃ and dried to constant weight to obtain multiphase infiltration composite powder.

[0014] Furthermore, the preparation method of the metastable dispersion base powder includes the following steps: D1. After uniformly mixing ferric oxide, chromium oxide, molybdenum oxide, silicon dioxide and aluminum powder, press them into cylindrical blocks, transfer the cylindrical blocks to a tube furnace at 900℃, ignite under argon protection, and then process them to obtain thermally reduced metal ingots. D2. Place the thermally reduced metal ingot into a vacuum induction furnace. After heating the furnace to 1600℃, introduce argon gas at a controlled pressure of 1.2MPa to atomize the metal ingot. Then, at 10... 4 Cooled to room temperature at a cooling rate of K / s, the fine powder was collected to obtain metastable dispersed base powder.

[0015] The principle for preparing metastable dispersion base powder is as follows: Ferric oxide, chromium oxide, and molybdenum oxide undergo a strongly exothermic aluminothermic reaction under the action of aluminum powder, generating corresponding metallic iron, chromium, molybdenum, and alumina dispersed phases. Simultaneously, silicon dioxide participates in the reaction to form partial Al-Si composite oxides, thus obtaining a homogeneous multi-element metal blank. This blank is then heated to a molten state in a vacuum induction furnace, and the melt is instantly broken into fine droplets by high-pressure inert gas atomization. 4 Rapid solidification is achieved at a cooling rate in the K / s range. This process suppresses the segregation of alloying elements and the precipitation of coarse phases, and solid solution forms a metastable solution structure rich in dispersed particles such as Al2O3 and SiO2. The resulting metastable dispersed matrix powder has high chemical homogeneity and refined dispersed oxide phases, providing excellent thermal stability and strengthening basis for subsequent alloy systems.

[0016] Furthermore, in step D1, the ratio of ferric oxide, chromium oxide, molybdenum oxide, silicon dioxide, and aluminum powder is a mass ratio. The post-processing includes: after combustion, cooling and removing the metal block, washing it three times with anhydrous ethanol and deionized water, and then drying it to constant weight in a vacuum drying oven at 80°C to obtain a thermally reduced metal ingot.

[0017] This invention also discloses a method for preparing a corrosion-resistant alloy mold steel material, comprising the following steps: S1. Nitrogen-fixed alloy powder, multiphase diffusion composite powder, metastable dispersion base powder and dispersant are added to the reaction vessel. The pH of the reaction system is adjusted to 4-5 using acetic acid. The mixture is stirred at room temperature for 1-2 hours. The post-treatment yields a cross-linked ternary mixed powder. S2. Add 0.5wt% graphene oxide to the cross-linked ternary powder, mix evenly, pack into a stainless steel sleeve, vacuum seal, and place in a hot isostatic pressing equipment for densification treatment. Keep warm and pressurize for 2 hours. After treatment, cool and remove, peel off the outer sleeve to obtain a high-density alloy billet. S3. Add the high-density alloy billet into a tube furnace, heat the tube furnace to 1030℃, hold for 20 minutes, then oil quench, and then temper twice at 520℃ for 2 hours each time. Cool to room temperature to obtain alloy mold steel.

[0018] The principle of preparing alloy mold steel is as follows: First, nitrogen-based alloy powder, multiphase diffusion composite powder, and metastable dispersion base powder are mixed at the molecular level in an acidic dispersion system through crosslinking. The dispersant promotes the formation of a stable silicon-oxygen network structure on the powder surface. Then, graphene oxide is added and subjected to hot isostatic pressing densification treatment. Under high temperature and high pressure, plastic flow and atomic diffusion bonding between powders are achieved. The graphene oxide is partially reduced to graphene, forming a fine and dispersed carbon-based interface layer at the grain boundaries, which improves the matrix density and interface bonding strength. After subsequent quenching and tempering heat treatment, a fine martensitic structure and dispersed nitride, boride, and oxide phases are formed inside the alloy, constructing a stable multiphase synergistic strengthening system, and finally, alloy mold steel is prepared.

[0019] Further, in step S1, the post-processing includes: after stirring, filtering the reaction solution to collect the filter cake, washing the filter cake three times each with anhydrous ethanol and deionized water, and transferring the filter cake to a vacuum drying oven at 80°C to dry to constant weight to obtain a cross-linked ternary mixed powder. Furthermore, in step S2, the equipment temperature is 1150℃ and the pressure is 150MPa.

[0020] The present invention has the following beneficial effects: The Fe-Cr-Mo-N solid solution system in the nitrogen-based alloy powder prepared by this invention can rapidly form a dense and stable passivation film at room temperature, enhancing the substrate's resistance to pitting and crevice corrosion in chloride environments. The Al-Si-B composite diffusion layer generated in the multiphase diffusion composite powder forms a continuous Al2O3-SiO2 passivation film on the metal surface, providing additional barrier protection for the substrate. The oxide particles dispersed in the metastable dispersed base powder refine the grains and stabilize the grain boundary structure, inhibiting the generation of corrosion microcouples. The graphene interface layer blocks the penetration and electron transfer of corrosive media at the microscopic level, further improving the interface corrosion resistance. Finally, through the chemical synergy and structural complementarity between multiphase powders, the material forms a composite protective film and a multi-level passivation system at room temperature, realizing a comprehensive corrosion resistance mechanism of solid solution strengthening, diffusion layer protection, dispersion passivation, and interface shielding, enabling the alloy mold steel to exhibit excellent corrosion resistance stability in both humid and chlorine-containing environments.

[0021] The Al–Si–B multi-element infiltration layer structure formed in the multiphase infiltration composite powder prepared by this invention forms a stable metallurgical bond with the matrix during hot isostatic pressing, enhancing grain boundary bonding and effectively preventing crack propagation. The fine dispersed oxide phase in the metastable dispersed matrix powder plays a dual role in second-phase reinforcement and grain refinement, improving the stress dispersion ability of the matrix. The Fe-Cr-Mo-N solid solution system in the nitrogen-solid alloy powder provides significant solid solution strengthening, while nitrogen atoms dissolved in the crystal lattice can suppress dislocation movement and improve the yield and tensile strength of the material. At the same time, the carbon-based reinforcing layer formed by graphene at the grain boundaries has excellent load transfer and interface passivation functions, further improving the strength and plasticity-toughness balance of the material. Finally, through the synergistic effect of multi-component powders, the material maintains high strength while still having good elongation at break, achieving synergistic optimization of strength and toughness, and exhibiting comprehensive mechanical properties and structural stability superior to traditional mold steel.

[0022] The metastable dispersed powder prepared by this invention contains oxide particles that stabilize the interface structure and inhibit grain boundary migration and corrosion channel expansion at high temperatures. The graphene interface layer further reduces the electrochemical activity between the metal and the medium, blocking the electron transfer path of the corrosion reaction. The Fe-Cr-Mo-N solid solution system provided by the nitrogen-solid alloy powder can still stably form a Cr2O3-MoO3 composite passivation film at high temperatures, significantly improving the material's resistance to oxidation and reduction corrosion in acidic media. The multiphase diffusion-layer composite powder generates a continuous and dense Al2O3-SiO2-B2O3 protective film under high temperature conditions, which has excellent chemical inertness and high-temperature adhesion, effectively blocking alkaline melting and oxidation penetration. Finally, through the multiple effects of solid solution passivation, diffusion layer shielding, dispersion stabilization and interface isolation, this alloy mold steel maintains extremely low mass loss in both high-temperature acidic and alkaline environments, showing superior high-temperature chemical corrosion resistance and structural stability compared to traditional mold steel. Detailed Implementation

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In this application, the silica used was purchased from Shanghai McLean Biochemical Technology Co., Ltd., with item number M741641; the graphene oxide used was purchased from Shanghai McLean Biochemical Technology Co., Ltd., with item number G768901.

[0025] Example 1 This embodiment provides a method for preparing nitrogen-based alloy powder, including the following steps: Step (1): Preparation of metal complex sol Weigh out 10.0g of ferric nitrate nonahydrate, 10.0g of chromium nitrate nonahydrate, 2.0g of ammonium molybdate and 1000.0mL of deionized water and add them to the reaction vessel. After stirring evenly, add 15.0g of citric acid and 8.0g of urea, adjust the pH of the reaction system to 6 and continue stirring for 20min to obtain a metal complex sol.

[0026] Step 2: Preparation of ternary oxide complex Weigh 1000.0g of metal complex sol and place it in a reaction vessel with a water bath temperature of 80℃. Keep it at the temperature and let it stand until no liquid is collected to obtain a ternary gel. Transfer the ternary gel to a muffle furnace with a temperature of 350℃ and keep it at the temperature for 50min. After the treatment is completed, wait for the muffle furnace to cool to room temperature, take out the material, and grind it to obtain a ternary oxide composite with a particle size of 20μm.

[0027] Step 3: Preparation of ternary reduced alloy powder Weigh 10.0g of ternary oxide composite and place it in a tube furnace. Heat the tube furnace to 800℃ at a heating rate of 10℃ / min under a hydrogen atmosphere. Maintain the hydrogen flow rate at 200mL / min and hold for 2 hours. After the reaction is complete, allow the tube furnace to cool naturally to room temperature to obtain ternary reduced alloy powder.

[0028] Step 4: Preparation of nitrogen-fixed alloy powder Weigh 6.0g of ternary reduction powder and transfer it to a nitriding reactor. Introduce ammonia gas and raise the temperature of the nitriding reactor to 700℃ at a heating rate of 8℃ / min. Control the nitrogen decomposition rate to 20% and keep it at that temperature for 2 hours. After the reaction is complete, allow the nitriding reactor to cool naturally to room temperature to obtain nitrogen-solid alloy powder.

[0029] Example 2 This embodiment provides a method for preparing nitrogen-based alloy powder, including the following steps: Step (1): Preparation of metal complex sol Weigh out 10.0g of ferric nitrate nonahydrate, 12.0g of chromium nitrate nonahydrate, 2.0g of ammonium molybdate and 1000.0mL of deionized water and add them to the reaction vessel. After stirring evenly, add 15.0g of citric acid and 10.0g of urea, adjust the pH of the reaction system to 7 and continue stirring for 30min to obtain a metal complex sol.

[0030] Step 2: Preparation of ternary oxide complex Weigh 1000.0g of metal complex sol and place it in a reaction vessel with a water bath temperature of 90℃. Keep it at the temperature and let it stand until no liquid is collected to obtain a ternary gel. Transfer the ternary gel to a muffle furnace with a temperature of 350℃ and keep it at the temperature for 60min. After the treatment is completed, wait for the muffle furnace to cool to room temperature, take out the material, and grind it to obtain a ternary oxide composite with a particle size of 30μm.

[0031] Step 3: Preparation of ternary reduced alloy powder Weigh 10.0g of ternary oxide composite and place it in a tube furnace. Under a hydrogen atmosphere, heat the tube furnace to 820℃ at a heating rate of 10℃ / min, maintain the hydrogen flow rate at 200mL / min and hold for 2h. After the reaction is complete, allow the tube furnace to cool naturally to room temperature to obtain ternary reduced alloy powder.

[0032] Step 4: Preparation of nitrogen-fixed alloy powder Weigh 6.0g of ternary reduction powder and transfer it to a nitriding reactor. Introduce ammonia gas and raise the temperature of the nitriding reactor to 720℃ at a heating rate of 12℃ / min. Control the nitrogen decomposition rate to 25% and keep it at that temperature for 2 hours. After the reaction is complete, allow the nitriding reactor to cool naturally to room temperature to obtain nitrogen-solid alloy powder.

[0033] Example 3 This embodiment provides a method for preparing nitrogen-based alloy powder, including the following steps: Step (1): Preparation of metal complex sol Weigh out 10.0g of ferric nitrate nonahydrate, 11.0g of chromium nitrate nonahydrate, 2.0g of ammonium molybdate and 1000.0mL of deionized water and add them to the reaction vessel. After stirring evenly, add 15.0g of citric acid and 9.0g of urea, adjust the pH of the reaction system to 6 and continue stirring for 25min to obtain a metal complex sol.

[0034] Step 2: Preparation of ternary oxide complex Weigh 1000.0g of metal complex sol and place it in a reaction vessel with a water bath temperature of 85℃. Keep it at the temperature and let it stand until no liquid is collected to obtain a ternary gel. Transfer the ternary gel to a muffle furnace with a temperature of 350℃ and keep it at the temperature for 55min. After the treatment is completed, wait for the muffle furnace to cool to room temperature, take out the material, and grind it to obtain a ternary oxide composite with a particle size of 25μm.

[0035] Step 3: Preparation of ternary reduced alloy powder Weigh 10.0g of ternary oxide composite and place it in a tube furnace. Under a hydrogen atmosphere, heat the tube furnace to 810℃ at a heating rate of 10℃ / min, maintain the hydrogen flow rate at 200mL / min and hold for 2h. After the reaction is complete, allow the tube furnace to cool naturally to room temperature to obtain ternary reduced alloy powder.

[0036] Step 4: Preparation of nitrogen-fixed alloy powder Weigh 6.0g of ternary reduction powder and transfer it to a nitriding reactor. Introduce ammonia gas and raise the temperature of the nitriding reactor to 710℃ at a heating rate of 10℃ / min. Control the nitrogen decomposition rate to 24% and keep it at that temperature for 2 hours. After the reaction is complete, allow the nitriding reactor to cool naturally to room temperature to obtain nitrogen-solid alloy powder.

[0037] Example 4 This embodiment provides a method for preparing multiphase infiltration composite powder, including the following steps: Step ①: Preparation of aluminum-silicon co-infiltration precursor Weigh out 8.0g aluminum powder, 3.0g aluminum chloride, 40.0g sodium chloride, 40.0g potassium chloride and 2.0g silicon dioxide and place them in a stainless steel reaction crucible. Then place the stainless steel reaction crucible under nitrogen protection and heat it to 700℃ and keep it at that temperature for 3 hours. After the temperature is maintained, let the crucible cool to room temperature, take out the material and wash it three times with anhydrous ethanol and deionized water respectively. Then dry it in a vacuum drying oven at 80℃ to constant weight to obtain the aluminum-silicon co-diffusion precursor.

[0038] Step 2: Preparation of multiphase infiltration composite powder Weigh out 8.0g of aluminum-silicon co-diffusion precursor, 2.0g of potassium carbonate and 180.0mL of N,N-dimethylformamide and add them to a high-temperature reactor. After stirring evenly, nitrogen gas is introduced for protection, followed by boron trichloride gas at a flow rate of 30mL / min. The reactor is then heated to 880℃ and kept at that temperature for 5h. After the heating is completed, the reactor is cooled to room temperature. The reaction liquid is filtered and the filter cake is collected. The filter cake is washed three times each with anhydrous ethanol and deionized water. The filter cake is then transferred to a vacuum drying oven at 80℃ and dried to constant weight to obtain multiphase infiltration composite powder.

[0039] Example 5 This embodiment provides a method for preparing multiphase infiltration composite powder, including the following steps: Step ①: Preparation of aluminum-silicon co-infiltration precursor Weigh out 10.0g aluminum powder, 5.0g aluminum chloride, 40.0g sodium chloride, 40.0g potassium chloride and 3.0g silicon dioxide and place them in a stainless steel reaction crucible. Then place the stainless steel reaction crucible under nitrogen protection and heat it to 700℃ and keep it at that temperature for 4 hours. After the temperature is maintained, let the crucible cool to room temperature, take out the material and wash it three times with anhydrous ethanol and deionized water respectively. Then dry it in a vacuum drying oven at 80℃ to constant weight to obtain the aluminum-silicon co-diffusion precursor.

[0040] Step 2: Preparation of multiphase infiltration composite powder Weigh out 10.0g of aluminum-silicon co-diffusion precursor, 2.0g of potassium carbonate and 200.0mL of N,N-dimethylformamide and add them to a high-temperature reactor. After stirring evenly, nitrogen gas is introduced for protection, followed by boron trichloride gas at a flow rate of 50mL / min. The reactor is then heated to 920℃ and kept at that temperature for 6 hours. After the heating is completed, the reactor is cooled to room temperature. The reaction liquid is filtered and the filter cake is collected. The filter cake is washed three times each with anhydrous ethanol and deionized water. The filter cake is then transferred to a vacuum drying oven at 80℃ and dried to constant weight to obtain multiphase infiltration composite powder.

[0041] Example 6 This embodiment provides a method for preparing multiphase infiltration composite powder, including the following steps: Step ①: Preparation of aluminum-silicon co-infiltration precursor Weigh out 9.0g aluminum powder, 4.0g aluminum chloride, 40.0g sodium chloride, 40.0g potassium chloride and 3.0g silicon dioxide and place them in a stainless steel reaction crucible. Then place the stainless steel reaction crucible under nitrogen protection and heat it to 700℃ and keep it at that temperature for 4 hours. After the temperature is maintained, let the crucible cool to room temperature, take out the material and wash it three times with anhydrous ethanol and deionized water respectively. Then dry it in a vacuum drying oven at 80℃ to constant weight to obtain the aluminum-silicon co-diffusion precursor.

[0042] Step 2: Preparation of multiphase infiltration composite powder Weigh out 9.0g of aluminum-silicon co-diffusion precursor, 2.0g of potassium carbonate and 200.0mL of N,N-dimethylformamide and add them to a high-temperature reactor. After stirring evenly, nitrogen gas is introduced for protection, followed by boron trichloride gas at a flow rate of 40mL / min. The reactor is then heated to 900℃ and kept at that temperature for 6 hours. After the heating is completed, the reactor is cooled to room temperature. The reaction liquid is filtered to collect the filter cake. The filter cake is washed three times each with anhydrous ethanol and deionized water. The filter cake is then transferred to a vacuum drying oven at 80℃ and dried to constant weight to obtain multiphase infiltration composite powder.

[0043] Example 7 This embodiment provides a method for preparing a metastable dispersion base powder, including the following steps: Step I: Preparation of thermally reduced metal blanks Weigh out 10.0g of ferric oxide, 2.0g of chromium oxide, 2.0g of molybdenum trioxide, 4.0g of silicon dioxide and 3.0g of aluminum powder, mix them evenly, press them into cylindrical blocks, and transfer the cylindrical blocks to a tube furnace at 900℃. Ignite them under argon protection. After combustion is complete, cool them and take out the metal blocks. Wash them three times with anhydrous ethanol and deionized water, and then dry them to constant weight in a vacuum drying oven at 80℃ to obtain thermally reduced metal ingots.

[0044] Step II: Preparation of metastable dispersion base powder Weigh out 15.0g of thermally reduced metal ingot and place it in a vacuum induction furnace. After heating the furnace to 1600℃, introduce argon gas and control the pressure at 1.2MPa to atomize the metal ingot. Then, at 10... 4 Cooled to room temperature at a cooling rate of K / s, the fine powder was collected to obtain metastable dispersed base powder.

[0045] Example 8 This embodiment provides a method for preparing a metastable dispersion base powder, including the following steps: Step I: Preparation of thermally reduced metal blanks Weigh out 10.0g of ferric oxide, 3.0g of chromium oxide, 3.0g of molybdenum trioxide, 5.0g of silicon dioxide and 4.0g of aluminum powder, mix them evenly, press them into cylindrical blocks, and transfer the cylindrical blocks to a tube furnace at 900℃. Ignite them under argon protection. After combustion is complete, cool them and take out the metal blocks. Wash them three times with anhydrous ethanol and deionized water, and then dry them to constant weight in a vacuum drying oven at 80℃ to obtain thermally reduced metal ingots.

[0046] Step II: Preparation of metastable dispersion base powder Weigh out 15.0g of thermally reduced metal ingot and place it in a vacuum induction furnace. After heating the furnace to 1600℃, introduce argon gas and control the pressure at 1.2MPa to atomize the metal ingot. Then, at 10... 4 Cooled to room temperature at a cooling rate of K / s, the fine powder was collected to obtain metastable dispersed base powder.

[0047] Example 9 This embodiment provides a method for preparing a metastable dispersion base powder, including the following steps: Step I: Preparation of thermally reduced metal blanks Weigh out 10.0g of ferric oxide, 2.5g of chromium oxide, 2.5g of molybdenum trioxide, 4.5g of silicon dioxide, and 3.6g of aluminum powder, mix them evenly, press them into cylindrical blocks, and transfer the cylindrical blocks to a tube furnace at 900℃. Ignite them under argon protection. After combustion is complete, cool them and remove the metal blocks. Wash them three times with anhydrous ethanol and deionized water, and then dry them to constant weight in a vacuum drying oven at 80℃ to obtain a thermally reduced metal ingot.

[0048] Step II: Preparation of metastable dispersion base powder Weigh out 15.0g of thermally reduced metal ingot and place it in a vacuum induction furnace. After heating the furnace to 1600℃, introduce argon gas and control the pressure at 1.2MPa to atomize the metal ingot. Then, at 10... 4 Cooled to room temperature at a cooling rate of K / s, the fine powder was collected to obtain metastable dispersed base powder.

[0049] Example 10 This embodiment provides a method for preparing corrosion-resistant alloy mold steel material, including the following steps: Step 1: Preparation of cross-linked ternary compound powder Weigh out 8.0 mL of tetraethyl orthosilicate, 40.0 mL of anhydrous ethanol, and 10.0 mL of deionized water and mix them to obtain a dispersant; By weight, 60 parts of nitrogen-solid alloy powder prepared in Example 1, 20 parts of multiphase infiltration composite powder prepared in Example 4, 20 parts of metastable dispersion base powder prepared in Example 7, and 50 parts of dispersant were weighed and added to the reaction vessel. The pH of the reaction system was adjusted to 4 using acetic acid, and the mixture was stirred at room temperature for 1 hour. After stirring, the reaction liquid was filtered to collect the filter cake. The filter cake was washed three times each with anhydrous ethanol and deionized water, and then transferred to a vacuum drying oven at 80°C to dry to constant weight to obtain cross-linked ternary mixed powder.

[0050] Step 2: Preparation of high-density alloy billets After adding 0.5 wt% graphene oxide to the cross-linked ternary compound powder and mixing it evenly, the powder was placed in a stainless steel sleeve, vacuum sealed, and then placed in a hot isostatic pressing (HIP) equipment for densification treatment. The equipment temperature was 1150℃ and the pressure was 150 MPa. The heat and pressure treatment was carried out for 2 hours. After the treatment was completed, the powder was cooled and removed, and the outer sleeve was peeled off to obtain a high-density alloy billet.

[0051] Step 3: Preparation of alloy mold steel A high-density alloy billet is added to a tube furnace, which is heated to 1030°C and held for 20 minutes before being oil quenched. The billet is then tempered twice at 520°C for 2 hours each time and cooled to room temperature to obtain alloy mold steel.

[0052] Example 11 This embodiment provides a method for preparing corrosion-resistant alloy mold steel material, including the following steps: Step 1: Preparation of cross-linked ternary compound powder Weigh out 10.0 mL of tetraethyl orthosilicate, 50.0 mL of anhydrous ethanol, and 12.0 mL of deionized water and mix them to obtain a dispersant; By weight, 60 parts of nitrogen-solid alloy powder prepared in Example 2, 25 parts of multiphase infiltration composite powder prepared in Example 5, 25 parts of metastable dispersion base powder prepared in Example 8, and 60 parts of dispersant were weighed and added to the reaction vessel. The pH of the reaction system was adjusted to 5 using acetic acid, and the mixture was stirred at room temperature for 2 hours. After stirring, the reaction liquid was filtered to collect the filter cake. The filter cake was washed three times each with anhydrous ethanol and deionized water, and then transferred to a vacuum drying oven at 80°C to dry to constant weight to obtain cross-linked ternary mixed powder.

[0053] Step 2: Preparation of high-density alloy billets After adding 0.5 wt% graphene oxide to the cross-linked ternary compound powder and mixing it evenly, the powder was placed in a stainless steel sleeve, vacuum sealed, and then placed in a hot isostatic pressing (HIP) equipment for densification treatment. The equipment temperature was 1150℃ and the pressure was 150 MPa. The heat and pressure treatment was carried out for 2 hours. After the treatment was completed, the powder was cooled and removed, and the outer sleeve was peeled off to obtain a high-density alloy billet.

[0054] Step 3: Preparation of alloy mold steel A high-density alloy billet is added to a tube furnace, which is heated to 1030°C and held for 20 minutes before being oil quenched. The billet is then tempered twice at 520°C for 2 hours each time and cooled to room temperature to obtain alloy mold steel.

[0055] Example 12 This embodiment provides a method for preparing corrosion-resistant alloy mold steel material, including the following steps: Step 1: Preparation of cross-linked ternary compound powder Weigh out 9.0 mL of tetraethyl orthosilicate, 45.0 mL of anhydrous ethanol and 12.0 mL of deionized water and mix them to obtain a dispersant; By weight, 60 parts of the nitrogen-solid alloy powder prepared in Example 3, 24 parts of the multiphase infiltration composite powder prepared in Example 6, 24 parts of the metastable dispersion base powder prepared in Example 9, and 54 parts of dispersant were weighed and added to the reaction vessel. The pH of the reaction system was adjusted to 4 using acetic acid, and the mixture was stirred at room temperature for 2 hours. After stirring, the reaction liquid was filtered to collect the filter cake. The filter cake was washed three times each with anhydrous ethanol and deionized water, and then transferred to a vacuum drying oven at 80°C to dry to constant weight to obtain the cross-linked ternary mixed powder.

[0056] Step 2: Preparation of high-density alloy billets After adding 0.5 wt% graphene oxide to the cross-linked ternary compound powder and mixing it evenly, the powder was placed in a stainless steel sleeve, vacuum sealed, and then placed in a hot isostatic pressing (HIP) equipment for densification treatment. The equipment temperature was 1150℃ and the pressure was 150 MPa. The heat and pressure treatment was carried out for 2 hours. After the treatment was completed, the powder was cooled and removed, and the outer sleeve was peeled off to obtain a high-density alloy billet.

[0057] Step 3: Preparation of alloy mold steel A high-density alloy billet is added to a tube furnace, which is heated to 1030°C and held for 20 minutes before being oil quenched. The billet is then tempered twice at 520°C for 2 hours each time and cooled to room temperature to obtain alloy mold steel.

[0058] Comparative Example 1 The difference between this comparative example and Example 12 is that graphene oxide is omitted in step two.

[0059] Comparative Example 2 The difference between this comparative example and Example 12 is that the nitrogen-solid alloy powder is omitted in step one, and the ternary reduced alloy powder prepared in step (3) is used to replace the nitrogen-solid alloy powder in an equal amount.

[0060] Comparative Example 3 The difference between this comparative example and Example 12 is that the multiphase infiltration composite powder is omitted in step one, and the aluminum-silicon co-infiltration precursor prepared in step ① is used to replace the multiphase infiltration composite powder in an equal amount.

[0061] Performance testing: The corrosion rates of the alloy mold steels prepared in Examples 10-12 and Comparative Examples 1-3 were determined according to the standard GB / T 17897-2016 "Corrosion of Metals and Alloys - Test Method for Pitting Corrosion of Stainless Steel with Ferric Chloride". The room temperature tensile strength and room temperature elongation at break of the alloy mold steels prepared in Examples 10-12 and Comparative Examples 1-3 were tested in accordance with the standard GB / T 228.1-2021 "Metallic materials, tensile testing - Part 1: Test method at room temperature". Referring to standard GB / T 42912-2023 "Corrosion of Metals and Alloys - High-Temperature Corrosion Test Method for Metallic Materials under Static Immersion in Molten Salt or Other Liquids", the alloy mold steels prepared in Examples 10-12 and Comparative Examples 1-3 were immersed in a boiling mixed system of sodium hydroxide, potassium permanganate, and deionized water in a ratio of 18g:3g:100mL, and a boiling system of citric acid and deionized water in a ratio of 1g:100mL. The high-temperature alkaline mass loss and high-temperature acid mass loss were measured. The specific data are shown in Table 1. Table 1 - Performance Test Data for Each Sample

[0062] Data Analysis: Comparative analysis of the data in Table 1 reveals that the alloy mold steel prepared by this invention exhibits a corrosion rate of 0.35%, a tensile strength of 1840 MPa, an elongation at break of 11.1%, and a high-temperature alkaline mass loss of 0.026 g while exhibiting a high-temperature acidic mass loss of 0.040 g. All these data are superior to the comparative example, indicating that… In Comparative Example 1, after the removal of graphene oxide, a continuous carbon-based interface layer no longer forms at the grain boundaries during the densification process. The transition zone between the grain boundaries and the matrix is ​​weakened, making it difficult to effectively "passivate" the residual pores and inclusions at the grain boundaries. The interface exhibits more sharp defect morphologies, and without the constraint on the corrosive medium and load transfer path, the corrosive medium can more easily penetrate along the grain boundaries and connect with the internal micropores, forming a through corrosion channel. At the same time, stress is concentrated at the sharp interfaces that have not been "smoothed," and microcracks are more likely to initiate and connect with each other under tensile loads. This leads to an increase in the number of pitting corrosion sources and a decrease in crack propagation resistance at room temperature, which macroscopically manifests as a decrease in corrosion resistance and a simultaneous deterioration in tensile strength and elongation at break. In Comparative Example 2, after replacing nitrogen-based alloy powder with ternary reduction alloy powder in equal amounts, the alloy system lost the nitrogen-related solid solution and interface regulation effects during subsequent sintering and hot isostatic pressing. The original lattice distortion in the crystal lattice was weakened, dislocation movement became more concentrated and intense, and local stress was difficult to disperse evenly. This made the matrix more prone to slip band aggregation and micropore nucleation under external loads and service environment. At the same time, the surface and near-surface layers lacked nitrogen-induced stable phase distribution, and the bonding area between the passivation film and the matrix became more singular. During corrosion, the film layer was prone to local instability and peeling, and the corrosion front advanced faster inward. The above structural evolution caused the yield strength and tensile limit of the material to decrease under tensile conditions, accompanied by increased local corrosion, and the overall tensile strength and corrosion resistance synergy deteriorated significantly. In Comparative Example 3, after replacing the multiphase infiltration composite powder with an aluminum-silicon co-infiltration precursor, the surface infiltration layer tended to evolve into a single Al-Si co-infiltration structure during the forming and subsequent heat treatment processes. The original multiphase gradient infiltration layer was simplified, and the phase composition and volume fraction distribution of the interface transition zone became monotonous. This resulted in a reduction in the thermal expansion mismatch buffering capacity between the infiltration layer and the matrix. Furthermore, without the synergistic regulation of the multiphase, the infiltration layer was more prone to local debonding and microcracks in high-temperature acid and alkali media. The medium rapidly penetrated along the cracks and eroded the infiltration layer / matrix interface, causing the protective layer to peel off in flakes and increasing the exposed area of ​​the matrix. Under repeated heat-corrosion coupling, surface damage accumulated continuously, forming uneven pits and stress concentration areas, which led to an increase in the high-temperature acid and alkali corrosion rate and further weakened the mechanical stability of the material under high-temperature conditions. This application uses nitrogen-based alloy powder, multiphase diffusion composite powder, metastable dispersion base powder, and graphene oxide as the constituent system. Each component participates in solid solution strengthening, diffusion densification, dispersion stabilization, and interface regulation during the forming and densification process, respectively, to construct a gradient and continuous composite structure. Nitrogen forms a stable solid solution in the crystal lattice and refines the grains. The diffusion composite powder generates a dense protective film on the surface, and the dispersed particles inhibit grain boundary migration at high temperatures. Meanwhile, the graphene oxide achieves stress dispersion and electrochemical shielding at the interface. These multiple effects are interconnected at different scales, enabling the alloy mold steel to have high strength, high plasticity, and excellent resistance to high-temperature acid and alkali corrosion. The material maintains structural integrity, interface stability, and balanced mechanical properties in the service environment, demonstrating a highly matched overall effect among the components within the system.

[0063] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A corrosion-resistant alloy mold steel material, characterized in that, The raw material composition includes the following parts by weight: 60 parts nitrogen-fixed alloy powder, 20-25 parts multiphase diffusion layer composite powder, 20-25 parts metastable dispersion base powder and 50-60 parts dispersant; The method for preparing the nitrogen-based alloy powder includes the following steps: A1. Place the ternary oxide complex into a tube furnace, heat the tube furnace to 800-820℃ in a hydrogen atmosphere, maintain the hydrogen flow rate at 200mL / min and keep it at the temperature for 2h. After the reaction is complete, let the tube furnace cool naturally to room temperature to obtain ternary reduced alloy powder. A2. Transfer the ternary reduction powder to a nitriding reactor, introduce ammonia gas and raise the temperature of the nitriding reactor to 700-720℃, control the ammonia decomposition rate and keep it at the temperature for 2 hours. After the reaction is completed, let the nitriding reactor cool naturally to room temperature to obtain nitrogen-solid alloy powder.

2. The corrosion-resistant alloy mold steel material according to claim 1, characterized in that, The dispersant is prepared by mixing tetraethyl orthosilicate, anhydrous ethanol and deionized water in a ratio of 8-10 mL: 40-50 mL: 10-12 mL; in step A1, the heating rate of the tube furnace is 10 °C / min; in step A2, the heating rate of the nitriding reactor is 8-12 °C / min, and the nitrogen decomposition rate is 20-25%.

3. The corrosion-resistant alloy mold steel material according to claim 1, characterized in that, The preparation method of the ternary oxide complex includes the following steps: B1. Add ferric nitrate nonahydrate, chromium nitrate nonahydrate, ammonium molybdate and deionized water to the reaction vessel, stir evenly, add citric acid and urea, adjust the pH of the reaction system to 6-7 and continue stirring for 20-30 minutes to obtain a metal complex sol. B2. Place the metal complex sol in a reaction vessel with a water bath temperature of 80-90℃, keep it at the temperature and let it stand until no liquid is collected to obtain a ternary gel. Transfer the ternary gel to a muffle furnace with a temperature of 350℃ and keep it at the temperature for 50-60 minutes. After the treatment is completed, wait for the muffle furnace to cool to room temperature, take out the material, and grind it to obtain a ternary oxide composite.

4. The corrosion-resistant alloy mold steel material according to claim 3, characterized in that, In step B1, the ratio of ferric nitrate nonahydrate, chromium nitrate nonahydrate, ammonium molybdate tetrahydrate, deionized water, citric acid, and urea is 1g:1.0-1.2g:0.2g:100mL:1.5g:0.8-1.0g; in step B2, the particle size of the ternary oxide complex is 20-30μm.

5. The corrosion-resistant alloy mold steel material according to claim 1, characterized in that, The preparation method of the multiphase infiltration composite powder includes the following steps: C1. Place aluminum powder, aluminum chloride, sodium chloride, potassium chloride and silicon dioxide into a stainless steel reaction crucible, then place the stainless steel reaction crucible under nitrogen protection and heat it to 700℃, keep it at that temperature for 3-4 hours, and then process it to obtain the aluminum-silicon co-diffusion precursor. C2. Add the aluminum-silicon co-diffusion precursor, potassium carbonate, and N,N-dimethylformamide to a high-temperature reactor, stir evenly, then introduce nitrogen gas for protection, followed by boron trichloride gas at a flow rate of 30-50 mL / min, and heat the reactor to 880-920℃ and keep it at that temperature for 5-6 hours. The post-treatment yields the multiphase infiltration composite powder.

6. The corrosion-resistant alloy mold steel material according to claim 5, characterized in that, In step C1, the ratio of aluminum powder, aluminum chloride, sodium chloride, potassium chloride, and silicon dioxide is 8-10g:3-5g:40g:40g:2-3g; in step C2, the ratio of aluminum-silicon co-infiltration precursor, potassium carbonate, and N,N-dimethylformamide is 8-10g:2g:180-200mL.

7. The corrosion-resistant alloy mold steel material according to claim 1, characterized in that, The preparation method of the metastable dispersion base powder includes the following steps: D1. After uniformly mixing ferric oxide, chromium oxide, molybdenum oxide, silicon dioxide and aluminum powder, press them into cylindrical blocks, transfer the cylindrical blocks to a tube furnace at 900℃, ignite under argon protection, and then process them to obtain thermally reduced metal ingots. D2. Place the thermally reduced metal ingot into a vacuum induction furnace. After heating the furnace to 1600℃, introduce argon gas at a controlled pressure of 1.2MPa to atomize the metal ingot. Then, at 10... 4 Cooled to room temperature at a cooling rate of K / s, the fine powder was collected to obtain metastable dispersed base powder.

8. The corrosion-resistant alloy mold steel material according to claim 7, characterized in that, In step D1, the ratio of ferric oxide, chromium oxide, molybdenum oxide, silicon dioxide, and aluminum powder is a mass ratio.

9. A method for preparing a corrosion-resistant alloy mold steel material as described in any one of claims 1-8, characterized in that, The method for preparing the corrosion-resistant alloy mold steel material includes the following steps: S1. Nitrogen-fixed alloy powder, multiphase diffusion composite powder, metastable dispersion base powder and dispersant are added to the reaction vessel. The pH of the reaction system is adjusted to 4-5 using acetic acid. The mixture is stirred at room temperature for 1-2 hours. The post-treatment yields a cross-linked ternary mixed powder. S2. Add 0.5wt% graphene oxide to the cross-linked ternary powder, mix evenly, pack into a stainless steel sleeve, vacuum seal, and place in a hot isostatic pressing equipment for densification treatment. Keep warm and pressurize for 2 hours. After treatment, cool and remove, peel off the outer sleeve to obtain a high-density alloy billet. S3. Add the high-density alloy billet into a tube furnace, heat the tube furnace to 1030℃, hold for 20 minutes, then oil quench, and then temper twice at 520℃ for 2 hours each time. Cool to room temperature to obtain alloy mold steel.

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