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CN-122013069-A - Preparation method of die steel for car lamp die

CN122013069ACN 122013069 ACN122013069 ACN 122013069ACN-122013069-A

Abstract

The invention discloses a preparation method of die steel for a car lamp die, and belongs to the technical field of die steel preparation. The die steel consists of matrix steel, a modified nano titanium carbide reinforced phase and a modified rare earth oxide complexing agent, wherein the steel matrix comprises the following components in percentage by mass of 0.45% of carbon, 0.8% of silicon, 1.2% of manganese, 13.5% of chromium, 2.0% of molybdenum, 0.6% of vanadium, 1.5% of nickel and 0.3% of niobium, and the balance of the components in percentage by mass of 1.0% of the modified nano titanium carbide reinforced phase, 0.2% of the modified rare earth oxide complexing agent and the balance of iron. According to the invention, three materials including matrix steel, a nano titanium carbide reinforced phase and a rare earth oxide complexing agent are synergistically modified, so that a trinity innovation system of 'modified matrix + reinforced phase enhancement + rare earth regulation and control' is constructed, synchronous improvement of hardness, toughness, polishing performance and corrosion resistance is realized, and the technical bottleneck of poor performance cooperativity of the traditional die steel is solved.

Inventors

  • WU MING
  • LIU ZHONGLI
  • WANG XIN

Assignees

  • 威海天润新材料科技有限公司

Dates

Publication Date
20260512
Application Date
20260224

Claims (8)

  1. 1. A die steel for a car lamp die is characterized by comprising, by mass, 0.45% of carbon, 0.8% of silicon, 1.2% of manganese, 13.5% of chromium, 2.0% of molybdenum, 0.6% of vanadium, 1.5% of nickel and 0.3% of niobium, wherein the steel matrix comprises, by mass, 1.0% of modified nano titanium carbide reinforcing phase, 0.2% of modified rare earth oxide complexing agent and the balance of iron.
  2. 2. The die steel for the car lamp die according to claim 1, wherein the preparation method of the modified nano titanium carbide reinforced phase is characterized in that industrial grade titanium carbide powder is placed in a planetary ball mill, absolute ethyl alcohol is used as a ball milling medium, the ball material ratio is 20:1, the ball milling rotation speed is 400r/min, the ball milling time is 12 hours, nano titanium carbide powder with the particle size of 500nm is obtained, the nano titanium carbide powder is immersed in 15% hydrochloric acid solution, stirred and reacted for 2 hours at 80 ℃, washed to be neutral and dried for 4 hours at 120 ℃, and the dried nano titanium carbide powder and aluminum powder are mixed according to the mass ratio of 10:1, and sintered for 2 hours at 1200 ℃ in an argon atmosphere, so that the modified nano titanium carbide reinforced phase is obtained.
  3. 3. The die steel for a car lamp die according to claim 1, wherein the preparation method of the modified rare earth oxide composite agent comprises the steps of mixing cerium oxide and lanthanum oxide according to a mass ratio of 3:2, adding the mixture into a nitric acid solution with a concentration of 20%, stirring and dissolving the mixture for 30 minutes at 60 ℃ to form a rare earth nitrate solution, adding an ammonium bicarbonate solution with a concentration of 10% into the solution, adjusting the pH value to 8.5 to generate rare earth carbonate precipitate, standing the precipitate for 30 minutes, filtering the precipitate, washing the precipitate with deionized water to neutrality, drying the precipitate at 110 ℃ for 6 hours, calcining the precipitate at 800 ℃ for 3 hours to obtain rare earth oxide composite powder, mixing the powder with a silane coupling agent according to a mass ratio of 100:3, and stirring the mixture in a high-speed mixer for 20 minutes at 1500r/min to obtain the modified rare earth oxide composite agent.
  4. 4. The die steel for the car lamp die according to claim 1, wherein the preparation method of the die steel is characterized in that the die steel is smelted by adopting a vacuum induction furnace, electrolytic manganese and ferrosilicon are added into molten steel for deoxidation and desulfurization pretreatment, prealloyed chromium-molybdenum-vanadium-nickel-niobium intermediate alloy is added, the smelting temperature is controlled to be 1580 ℃, the temperature is kept for 60 minutes, argon is introduced into the die steel for stirring, the flow rate of the argon is 5L/min, and the molten steel with a uniform composition is obtained.
  5. 5. The die steel for a lamp die according to claim 1, wherein the industrial grade titanium carbide powder has an original particle size of 50 μm, is refined to 500nm after ball milling, acid washing and aluminum powder sintering modification, and forms a titanium aluminide transition layer on the surface.
  6. 6. The die steel for a lamp die according to claim 1, wherein the modified rare earth oxide compound is prepared by dissolving, precipitating and calcining cerium oxide and lanthanum oxide, and then refining the grain size to 1-2 μm, and the surface is coated with a silane coupling agent layer.
  7. 7. The die steel for a vehicular lamp die according to claim 1, wherein the die steel has a hardness of 63-65HRC, an impact toughness of 36-38J/cm2, a surface roughness Ra after polishing of 0.014 μm or less, a corrosion rate of 0.004mm/a or less in 48 hours in salt spray test, and a service life of 16 ten thousand dies or more.
  8. 8. A method for producing the die steel for a lamp die according to any one of claims 1 to 7, comprising the steps of: S1, smelting matrix steel, namely adding industrial pure iron with the purity of 99.9%, electrolytic manganese, ferrosilicon and chromium-molybdenum-vanadium-nickel-niobium prealloy intermediate alloy into a vacuum induction furnace, vacuumizing to the vacuum degree of 0.001MPa, heating to 1580 ℃, preserving heat for 60 minutes, and introducing argon with the flow of 5L/min for stirring to obtain matrix molten steel; s2, adding a reinforcing phase and a modifier, namely uniformly adding the modified nano titanium carbide reinforcing phase into the matrix molten steel, continuously preserving heat for 30 minutes, and stirring at an argon flow of 3L/min; s3, pouring and molding, namely pouring the uniformly mixed molten steel into a die preheated to 300 ℃ at a pouring speed of 50mm/min under the protection of argon, and naturally cooling to room temperature to obtain a die steel cast ingot; S4, forging, namely heating the cast ingot to 1150 ℃, preserving heat for 2.5 hours, then performing three-way forging, wherein the forging ratio is 5:1, the rolling reduction of each forging is 10mm, the internal structure of the forging is ensured to be compact, the defects of looseness and air holes are avoided, the heat is preserved for 30 minutes after each forging, the cast ingot is finally forged into a plate with the thickness of 50mm, and the cooling speed is controlled to be 5 ℃ per minute in the forging process; s5, annealing treatment, namely heating the forged plate to 860 ℃, preserving heat for 4 hours, then cooling to 500 ℃ at a cooling speed of 2 ℃ per minute, and then air-cooling to room temperature; s6, quenching treatment, namely heating the annealed plate to 1050 ℃, preserving heat for 1.5 hours, and then adopting oil cooling quenching, wherein the cooling speed is 30 ℃ per minute, the quenching oil temperature is controlled to 50 ℃, so that uniform cooling is ensured, and deformation and cracking of steel pieces are avoided; s7, tempering, namely heating the quenched steel piece to 220 ℃, preserving heat for 3 hours, then air-cooling to room temperature, tempering for three times, and air-cooling to room temperature after each tempering, thereby finally obtaining the die steel for the car lamp die.

Description

Preparation method of die steel for car lamp die Technical Field The invention relates to the technical field of die steel preparation, in particular to a preparation method of die steel for a car lamp die. Background The car lamp die is used as core equipment for car lamp production, has extremely high requirements on the performance of die steel, not only has excellent hardness and wear resistance to ensure the service life of the die, but also has good toughness, polishing performance and corrosion resistance to ensure the high-precision molding and surface quality of car lamp products. The traditional die steel for the car lamp die adopts Cr12MoV, S136 and other conventional marks, and the preparation process is generally a conventional process of arc furnace smelting, forging, annealing, quenching and tempering, but has the following remarkable defects: The conventional die steel has poor performance consistency, the hardness and toughness are difficult to be compatible, for example, the hardness of Cr12MoV steel can reach HRC60-62 after quenching and tempering, but the impact toughness is only 15-20J/cm < 2 >, and the phenomena of angle collapse and cracking are easy to occur in the process of processing and using a complex cavity of a car lamp die; The polishing performance is insufficient, coarse carbide inclusions exist in the traditional die steel, the size is more than 5-10 mu m, the surface roughness of the polished die steel is difficult to reach the requirement of the car lamp die with Ra less than or equal to 0.02 mu m, and the light transmittance and the appearance texture of the car lamp product are affected; The corrosion resistance is poor, namely, the mold of the car lamp is contacted with release agent, impurities in cooling water and the like in the use process, the conventional mold steel is easy to rust, so that spots appear on the surface of a mold cavity, the quality of the car lamp is further influenced, and the maintenance period of the mold is short (usually less than or equal to 6 months); the service life is limited, and the service life of the traditional car lamp die is usually only 5-8 ten thousand times due to the contradiction between wear resistance and toughness and the local abrasion aggravation caused by uneven carbide distribution, so that the requirement of mass production is difficult to meet. The prior art has the defects that various optimization schemes are provided for improving the performance of the car lamp die steel, but the improvement is insufficient. For example, patent CN202010567890.3 discloses a preparation method of ultra-high hardness die steel, which increases the hardness by increasing the content of chromium and molybdenum elements, but causes further reduction of toughness, impact toughness is only 12-16J/cm < 2 >, patent CN201910876543.2 adopts vacuum arc furnace smelting to improve molten steel purity, but does not effectively regulate and control the form and distribution of carbide, polishing performance is limited to increase, surface roughness can only reach Ra0.03-0.04 μm, and other technologies increase wear resistance by surface nitriding treatment, but the thickness of a nitride layer is uneven, brittle cracking is easy to occur, and the problem of insufficient performance of a die steel matrix cannot be fundamentally solved. The core problems of the prior art are that systematic collaborative innovation is not carried out on matrix steel, strengthening phase and preparation process of the die steel, synchronous improvement of hardness, toughness, polishing performance and corrosion resistance cannot be realized by single modification or process optimization, and the specific use scene of the car lamp die is not targeted, so that the comprehensive performance of the die steel is difficult to meet the production requirement of high-end car lamps. Disclosure of Invention The invention aims to provide a preparation method of the die steel for the car lamp die, which is used for obtaining the die steel for the car lamp die with ultrahigh hardness, excellent toughness, excellent polishing performance and corrosion resistance by carrying out targeted modification on three materials, namely matrix steel, nano titanium carbide reinforced phase and rare earth oxide complexing agent and optimizing the preparation process, so that the service life of the die is prolonged, the production cost is reduced, and the requirements of high precision and high stability in the production of high-end car lamps are met. The technical scheme is that the die steel for the car lamp die comprises matrix steel, a modified nano titanium carbide reinforced phase and a modified rare earth oxide complexing agent, wherein the steel matrix comprises the following components in percentage by mass of 0.45% of carbon, 0.8% of silicon, 1.2% of manganese, 13.5% of chromium, 2.0% of molybdenum, 0.6% of vanadium, 1.5% of nickel and 0.3% of niobium, and the balance of iron. Pr