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CN-121992279-A - High-purity and high-toughness hot work die steel and preparation method thereof

CN121992279ACN 121992279 ACN121992279 ACN 121992279ACN-121992279-A

Abstract

The invention relates to a preparation method of high-purity and high-toughness hot-work die steel, which comprises the following steps of S1, electric furnace smelting, S2, ladle refining, S3, vacuum refining, S4, die casting of electrode blanks, S5, annealing of the electrode blanks, S6, electroslag remelting, surface polishing of the electrode blanks, smelting by adopting a quaternary slag system of calcium fluoride, aluminum oxide, magnesium oxide and silicon dioxide, wherein the melting speed of a starting point in a steady-state stage of electroslag smelting is 7-10 kg/min, the melting speed of an end point is 5.0-8.0 kg/min, an electroslag ingot is obtained, then the electric furnace is cooled for 80-100 min, S7, forging, S8, pretreatment after forging, and S9, solid solution and spheroidization final treatment. The invention is based on the common heat-used die steel H13, and the prepared product has excellent high hardness, high purity and high toughness performance by fine adjustment of chemical components and special smelting, forging and heat treatment processes. The cracking resistance of the die manufactured by the material is greatly improved, the service life of the die is prolonged, and the use cost of the die is greatly reduced.

Inventors

  • GUAN HAILONG
  • DING HAIFENG
  • OU ZHENGWEI
  • ZHU WEIFENG
  • Su Xuting
  • JIANG HAIQING
  • QIAN XIAOLIANG
  • ZHOU PENG
  • SHEN WEIXIN

Assignees

  • 江苏宏晟模具钢材料科技有限公司

Dates

Publication Date
20260508
Application Date
20260116

Claims (10)

  1. 1. A preparation method of high-purity and high-toughness hot work die steel is characterized by comprising the following steps of, S1, electric furnace smelting, namely preparing ingredients of scrap steel and alloy materials in advance according to the content of chemical components of smelting steel types, smelting the scrap steel in an electric furnace, carrying out oxidation deslagging on the temperature of molten steel at not less than 1630 ℃, adding the alloy materials after deslagging and completely melting the alloy materials, then adding lime and fluorite to form alkaline slag, dephosphorizing and desulfurizing molten steel in the electric furnace, and when the temperature of the molten steel is not less than 1620 ℃, adding aluminum wires for deoxidization and tapping; Wherein the hot-work die steel comprises the following components in percentage by mass ,C 0.35%~0.40%、Mn 0.30%~0.50%、Si 0.70%~0.90%、S≤0.001%、P≤0.010%、Cr 4.90%~5.10%、Mo 1.20%~1.50%、V 0.80%~1.10%,, the balance of Fe, the residual gas content is H less than or equal to 1.5ppm, O less than or equal to 13ppm, N less than or equal to 90ppm, the residual harmful elements Cu less than or equal to 0.10%, and Ti, sn and Pb less than or equal to 0.002%; s2, refining by a ladle refining furnace, namely transferring molten steel smelted by an electric furnace into a ladle, and lifting the ladle to a refining furnace seat for refining; S3, refining in a vacuum refining furnace, namely refining in the vacuum refining furnace, namely, a four-stage pump of the vacuum refining furnace, wherein the final vacuum degree is less than or equal to 35Pa, the vacuum time is maintained for more than 18 minutes for two times, and the target value of residual gas nitrogen is less than or equal to 80ppm; S4, die casting an electrode blank; s5, annealing the electrode blank; S6, electroslag remelting, namely adopting the electrode blank obtained in the step S5 to carry out surface polishing, adopting a quaternary slag system of calcium fluoride, aluminum oxide, magnesium oxide and silicon dioxide to carry out smelting, wherein the melting speed value of a starting point in a steady-state stage of electroslag smelting is 7-10 kg/min, the melting speed value of a finishing point is 5.0-8.0 kg/min, obtaining an electroslag ingot, and then cooling the electroslag ingot in a power failure furnace for 80-100 min and then carrying out a forging process; s7, forging; S8, preprocessing after forging; s9, solid solution and spheroidization final treatment.
  2. 2. The preparation method of the high-purity high-toughness hot work die steel is characterized in that in the step S2, the concrete process of refining in a ladle refining furnace is that molten steel is transferred to a ladle after electric furnace smelting, lifted to a refining furnace seat, slag materials CaO, caF 2 and C-Si powder are added to reduce and manufacture primary white slag, corresponding alloy materials are added according to deviation of actual components and target components of the molten steel in the refining furnace seat, component fine adjustment, desulfurization and deoxidation operations are completed, the white slag is removed after the operation is finished, then the temperature of the molten steel is reheated to be more than or equal to 1620 ℃, and CaO, caF 2 , C-Si powder and red brick heads are added to manufacture secondary white slag.
  3. 3. The method for preparing high-purity and high-toughness hot work die steel according to claim 1, wherein in the step S4, the specific process of die casting the electrode blank is that an ingot mould is preheated to 40-60 ℃, argon is filled into the ingot mould, each ingot mould is filled with argon for 3-5 min, an argon pipe is withdrawn, and the ingot mould is covered by a cover and then is cast.
  4. 4. The method for preparing high-purity and high-toughness hot work die steel according to claim 3, wherein in the step S4, an asbestos cloth added argon protection casting is adopted for protection in the whole casting process, the argon protection flow is 15-26 m 3 /h, the casting time is 4-8 min, the diameter of an electrode blank is 450-910 mm, and the die is removed after 3-5 h.
  5. 5. The method for preparing high-purity and high-toughness hot work die steel according to claim 1, wherein in the step S5, the electrode blank is annealed, the annealing temperature is 850-870 ℃, the heat preservation time is 1-1.5 min/mm, and the furnace cooling is carried out until the temperature reaches 300-380 ℃.
  6. 6. The method for preparing high-purity and high-toughness hot work die steel according to claim 1, wherein in the step S7, the specific forging process is that the electroslag ingot obtained in the step S6 is heated to 1290-1310 ℃, is kept at a temperature of 40-50 h for diffusion homogenization, is cooled to 1240-1260 ℃ by furnace cooling, is kept at a temperature of 6-10 h, and is discharged from a furnace for one firing time to finish Z, X, Y three-way upsetting, drawing and cogging and is drawn to a finished product size along the Z direction.
  7. 7. The method for preparing high-purity and high-toughness hot work die steel according to claim 1, wherein in the step S8, the specific process of pre-treatment after forging is that the forging stock obtained in the step S7 is air-cooled to the large surface temperature of 680-720 ℃, then water is added for limiting cooling control, precipitation of carbide in the grain boundary is inhibited, namely, water is cooled once to the large surface temperature of the blank of less than or equal to 250 ℃, then the blank is put into a heat treatment furnace, heated to 680-720 ℃, and heat preservation is carried out for 20-30 hours for tempering treatment.
  8. 8. The method for preparing high-purity and high-toughness hot work die steel according to claim 1, wherein in the step S9, the specific operation of solid solution and spheroidization is that the workpiece obtained in the step S8 is placed into a heating furnace, the temperature is raised to 1010-1040 ℃ along with the furnace, the temperature is kept for 10-20 h, the workpiece is cooled by adopting a direct water-air bottom mode, the workpiece is cooled to the maximum temperature of less than or equal to 250 ℃ after water cooling, the workpiece is placed into an annealing furnace after cooling, the workpiece is heated to 820-860 ℃ and is kept for 10-20 h, and the workpiece is discharged from the furnace to below 500 ℃ and cooled to room temperature after cooling.
  9. 9. The method for producing high purity, high toughness hot work die steel according to claim 8, wherein in step S9, the furnace cooling rate is 10 to 20 ℃.
  10. 10. The hot working die steel with high purity and high toughness is characterized by being prepared by adopting the preparation method according to any one of claims 1-9, wherein the hot working die steel comprises the following components in percentage by mass ,C 0.35%~0.40%、Mn 0.30%~0.50%、Si 0.70%~0.90%、S≤0.001%、P≤0.010%、Cr 4.90%~5.10%、Mo 1.20%~1.50%、V 0.80%~1.10%,, the balance of Fe, the residual gas content is H less than or equal to 1.5ppm, O less than or equal to 13ppm and N less than or equal to 90ppm, the residual harmful elements Cu less than or equal to 0.10%, and the Ti, sn and Pb are all less than or equal to 0.002%.

Description

High-purity and high-toughness hot work die steel and preparation method thereof Technical Field The invention relates to the technical field of die steel materials and metallurgical preparation, in particular to high-purity and high-toughness hot work die steel and a preparation method thereof. The die steel is suitable for manufacturing large, precise, complex and key industrial dies requiring long service life, particularly can be applied to die casting dies of engines, motors and the like, new energy automobile bodies, battery box forming dies, and processing and manufacturing high-end dies of car covering parts and the like, and can meet the strict energy requirements of die materials in the field of manufacturing high-end equipment. Background With the rapid development of modern industry, the die is used as core equipment for processing and forming parts, and the application range of the die covers a plurality of key industries such as automobiles, electronics, instruments, household appliances, aerospace, building materials, motors, communication equipment and the like. According to industry statistics, about 60% -80% of parts in the fields need to be processed and formed by means of a die, and the die is covered with the reputation of 'industry master', so that the technical level of the die directly determines the product quality, production efficiency and manufacturing cost of downstream industries. By 2025, the global mold market size has broken through $2000 billion, china contributed more than 35% of its share, and was the first to stabilize the world, becoming the core driving force for the development of the global mold industry. From the industrial driving effect, the pulling effect of the mold industry on related industries is remarkable. According to industry measurement and calculation, the driving ratio of the die industry to the upstream and downstream related industries is about 1:100, namely, each time the die industry grows by 1 hundred million yuan of output value, the related industries can be directly or indirectly driven to realize 100 hundred million yuan of output value growth, and the die industry is an important supporting force for promoting the transformation and upgrading of the manufacturing industry. At present, the total industrial yield of the global die industry keeps continuously growing, china becomes the forefront country of the world with the total die steel production amount by virtue of a perfect industrial system and huge market demands, and the number of die steel production enterprises is numerous, so that a large-scale industrial foundation is formed. The H13 steel is one of the hot work die steels with the largest market demand and the most extensive application at present, has better comprehensive mechanical properties, but still can not meet the use requirements of high-end dies in the aspects of purity, high toughness and the like. Therefore, the component optimization and the preparation process improvement are carried out on the basis of H13 steel, and the development of high-purity high-toughness high-performance hot work die steel becomes an urgent need for guaranteeing the autonomous development of high-end manufacturing industry. The research and industrialization of the high-performance hot-working die steel can replace imported materials on the premise of meeting the use conditions of customers, further improve the domestic substitution rate of the high-end die steel (about 65% of the imported substitution rate of the current high-end product), help customers to obviously reduce purchasing cost (the price of domestic high-end die steel is 30% -40% lower than that of imported high-end die steel), shorten production period, and realize maximization of benefits, and meanwhile, the research and industrialization of the die steel industry structure in China is facilitated to promote the core competitiveness of the die steel industry in China, and the development opportunity of the whole-ball die market in the scale of 2000 hundred million dollars and the high-frequency iteration requirement of the emerging industry such as domestic new energy automobiles are better adapted. Disclosure of Invention The first aim of the invention is to provide high-purity and high-toughness hot-work die steel and a preparation method thereof, wherein the prepared product has excellent high-hardness, high-purity and high-toughness performances by taking the common hot-work die steel H13 as the basis, and adopting special smelting, forging and heat treatment processes through fine adjustment of chemical components. The cracking resistance of the die manufactured by the material is greatly improved, the service life of the die is prolonged, and the use cost of the die is greatly reduced. In order to achieve the aim of the invention, the invention provides a preparation method of high-purity and high-toughness hot work die steel, which comprises the following steps, S1, el