CN-121976003-A - Preparation method of multi-element alloy regulated isothermal quenching high-wear-resistance high-toughness die steel

Abstract

The invention relates to the technical field of metal material treatment, and provides a preparation method of multi-element alloy regulated isothermal quenching high wear-resistant tough die steel, which comprises the steps of casting multi-element alloy steel ingots according to preset alloy components, and performing heat treatment after forging to obtain preformed blanks; and cooling the homogeneous austenitic blank to a pre-set bainite transformation temperature zone, and carrying out isothermal quenching treatment on the homogeneous austenitic blank in the bainite transformation temperature zone to obtain the die steel. The invention can effectively solve the technical contradiction that the traditional quenching internal stress is large and the tempering is difficult to cooperatively optimize the toughness of the wear-resistant phase and the matrix, and fundamentally avoids the problems of early cracking or tipping of the die.

Inventors

• LIU JIANYI
• LIU JUNHUI
• YANG LIANHUA

Assignees

• 深圳市重诚金属制品有限公司

Dates

Publication Date

20260505

Application Date

20260204

Claims (10)

1. 1. A preparation method of multi-element alloy regulated isothermal quenching high wear-resistant tough die steel is characterized by comprising the following steps: casting a multi-element alloy steel ingot of the die steel to be prepared according to a preset alloy composition, wherein the alloy composition at least comprises silicon for inhibiting a brittle phase and stabilizing residual austenite, and molybdenum for improving hardenability and secondary hardening; Performing post-forging heat treatment on the multi-element alloy steel ingot to obtain a preformed blank, and heating the preformed blank to an austenitizing temperature to perform austenitizing treatment on the preformed blank to obtain a homogeneous austenitic blank; and cooling the homogeneous austenitic blank to a preset bainite transformation temperature zone, and carrying out isothermal quenching treatment on the homogeneous austenitic blank in the bainite transformation temperature zone to obtain the die steel.
2. 2. The method for preparing the multi-element alloy controlled austempered high wear-resistant tough die steel according to claim 1, wherein the austempering treatment of the homogeneous austenitic blank is performed in the bainite transformation temperature zone to obtain the die steel, and the method comprises the following steps: Immersing the homogeneous austenitic blank in a molten salt bath maintained in the bainite transformation temperature zone so as to rapidly cool the homogeneous austenitic blank and enter an isothermal state to obtain an isothermal treatment blank; Isothermal holding the isothermally treated billet in the molten salt bath to obtain a phase change completed billet; and removing the phase-change completed blank from the molten salt bath and performing air cooling to obtain the die steel.
3. 3. The method for preparing a multi-element alloy controlled austempered high wear resistant tough mold steel of claim 2, wherein the isothermally processed billet is isothermally held in the molten salt bath to obtain a phase change completed billet, comprising: carrying out first-stage isothermal holding on the isothermal treatment blank in the molten salt bath at a constant temperature to finish main bainite transformation of the isothermal treatment blank so as to obtain a preliminary phase change blank; Carrying out second-stage isothermal holding on the preliminary phase-change blank in the molten salt bath at a similar temperature to promote the residual austenite in the preliminary phase-change blank to be stable and rich in carbon, so as to obtain the phase-change completed blank; wherein the difference between the similar temperature and the constant temperature is within + -30 ℃.
4. 4. The method for preparing the multi-element alloy regulated austempered high wear-resistant tough die steel according to claim 1, wherein the multi-element alloy steel ingot is subjected to post-forging heat treatment to obtain a preformed blank, and the method comprises the following steps: Heating the multi-element alloy steel ingot to a forging temperature and preserving heat so as to carry out multidirectional upsetting forging treatment on the multi-element alloy steel ingot to obtain a preliminary deformed blank; and after the preliminary deformed blank is air-cooled to room temperature, carrying out high-temperature homogenizing diffusion annealing treatment on the preliminary deformed blank to obtain a preformed blank.
5. 5. The method for preparing the multi-element alloy regulated austempered high-wear-resistance tough die steel according to claim 4, wherein the multi-element alloy steel ingot is heated to a forging temperature and is insulated so as to perform multidirectional upsetting forging treatment on the multi-element alloy steel ingot to obtain a preliminary deformed blank, and the method comprises the following steps: Performing three-way alternate upsetting and drawing treatment on the heated multi-element alloy steel ingot to obtain a refined deformed blank; and carrying out stress relief annealing treatment on the refined deformed blank to obtain the preliminary deformed blank.
6. 6. The method for preparing the multi-element alloy regulated austempered high wear-resistant tough mold steel according to claim 5, wherein the three-way alternate upsetting and drawing process is performed on the heated multi-element alloy steel ingot, and the method comprises the following steps: Performing primary upsetting and drawing on the heated multi-element alloy steel ingot in a first direction to obtain a primary deformed blank; After rotating the primary deformation blank around the axis by a preset angle, performing secondary upsetting and drawing in a second direction to obtain a secondary deformation blank; After the secondary deformation blank rotates around the axis of the secondary deformation blank again for the preset angle, upsetting and drawing out are carried out for three times in a third direction, and the refined deformation blank is obtained; The first direction, the second direction and the third direction are perpendicular to each other in space.
7. 7. The method for preparing the multi-element alloy controlled austempered high wear-resistant tough die steel of claim 1, wherein the pre-forming blank is heated to an austenitizing temperature to perform austenitizing treatment of the pre-forming blank to obtain a homogeneous austenitic blank, comprising: determining the Ac1 transformation point of the preform; placing the preformed blank in a controllable atmosphere furnace, and carrying out first-stage heat preservation on the preformed blank after the preformed blank is heated to a preheating temperature lower than the Ac1 transformation point; heating the preformed blank subjected to the first-stage heat preservation to the austenitizing temperature, and carrying out second-stage heat preservation on the preformed blank; and after the second-stage heat preservation is finished, removing the preformed blank in the controlled atmosphere furnace to obtain a homogeneous austenitic blank.
8. 8. The method for preparing the multi-element alloy controlled austempered high-wear-resistance tough die steel according to claim 7, wherein the purpose of the first-stage heat preservation is to make the whole temperature of the preformed blank uniform and complete the pre-transformation of partial tissues, and the purpose of the second-stage heat preservation is to ensure the sufficient solid solution of carbon and alloy elements in the preformed blank and the homogenization of austenite components.
9. 9. The method for preparing the multi-element alloy regulated austempered high-wear-resistance tough die steel according to claim 7, wherein the Ac1 transformation point is an initial temperature of the preformed blank, measured by a thermal expansion method, for starting transformation to austenite in a heating process, the austenitizing temperature is set to be 30-100 ℃ above an Ac3 transformation point, wherein the Ac3 transformation point is a critical temperature of the preformed blank for finishing transformation to austenite in the heating process, and the preheating temperature is selected to be 50-100 ℃ below the Ac1 transformation point.
10. 10. The method for preparing the multi-element alloy controlled austempered high-wear-resistance tough mold steel according to claim 1, wherein the multi-element alloy steel ingot for preparing the mold steel is cast according to preset alloy components, and comprises the following steps: alloy raw materials corresponding to preset alloy components are placed in a vacuum induction melting furnace for melting and refining treatment, so that purified molten steel is obtained; Carrying out directional solidification treatment on the purified molten steel to obtain a uniform cast steel ingot; And carrying out high-temperature homogenization diffusion annealing treatment on the uniform cast steel ingot to obtain a multi-element alloy steel ingot.

Description

Preparation method of multi-element alloy regulated isothermal quenching high-wear-resistance high-toughness die steel Technical Field The invention relates to a preparation method of multi-element alloy regulated isothermal quenching high wear-resistant tough die steel, and belongs to the technical field of metal material treatment. Background In the high-end manufacturing field, the high-wear-resistance tough die steel is used as a core material for precise forming processing, the wear resistance and the toughness matching degree of the high-wear-resistance tough die steel directly determine the service life of a die and the precision of a formed part, and the market provides higher standards for the comprehensive mechanical properties of the high-wear-resistance tough die steel along with continuous upgrading of the requirements of industries such as aerospace, automobile parts and the like on precise forming. However, the conventional method for preparing the die steel mainly combines a continuous heat treatment process of quenching and high-temperature tempering to regulate and control the steel structure, so that the base hardness and strength of the die steel can be improved, but huge internal stress is easy to generate in the quenching process, the subsequent tempering treatment is difficult to realize the cooperative optimization of the toughness of the wear-resistant phase and the matrix, and the defects can cause the problem that the die is easy to crack or break in early stage under complex stress. Disclosure of Invention The invention provides a preparation method of multi-element alloy regulated isothermal quenching high wear-resistant tough die steel, which mainly aims to effectively solve the technical contradiction that the traditional quenching internal stress is large and tempering is difficult to cooperatively optimize the toughness of a wear-resistant phase and a matrix, and fundamentally avoids the problems of early cracking or tipping of the die. In order to achieve the above purpose, the preparation method of the multi-element alloy regulated austempered high wear-resistant tough die steel provided by the invention comprises the following steps: casting a multi-element alloy steel ingot of the die steel to be prepared according to a preset alloy composition, wherein the alloy composition at least comprises silicon for inhibiting a brittle phase and stabilizing residual austenite, and molybdenum for improving hardenability and secondary hardening; Performing post-forging heat treatment on the multi-element alloy steel ingot to obtain a preformed blank, and heating the preformed blank to an austenitizing temperature to perform austenitizing treatment on the preformed blank to obtain a homogeneous austenitic blank; and cooling the homogeneous austenitic blank to a preset bainite transformation temperature zone, and carrying out isothermal quenching treatment on the homogeneous austenitic blank in the bainite transformation temperature zone to obtain the die steel. Optionally, performing austempering treatment of the homogeneous austenitic blank in the bainite transformation temperature zone to obtain the die steel, including: Immersing the homogeneous austenitic blank in a molten salt bath maintained in the bainite transformation temperature zone so as to rapidly cool the homogeneous austenitic blank and enter an isothermal state to obtain an isothermal treatment blank; Isothermal holding the isothermally treated billet in the molten salt bath to obtain a phase change completed billet; and removing the phase-change completed blank from the molten salt bath and performing air cooling to obtain the die steel. Optionally, isothermally holding the isothermally treated blank in the molten salt bath to obtain a phase-change completed blank, comprising: carrying out first-stage isothermal holding on the isothermal treatment blank in the molten salt bath at a constant temperature to finish main bainite transformation of the isothermal treatment blank so as to obtain a preliminary phase change blank; Carrying out second-stage isothermal holding on the preliminary phase-change blank in the molten salt bath at a similar temperature to promote the residual austenite in the preliminary phase-change blank to be stable and rich in carbon, so as to obtain the phase-change completed blank; wherein the difference between the similar temperature and the constant temperature is within + -30 ℃. Optionally, performing post-forging heat treatment on the multi-element alloy steel ingot to obtain a preformed blank, wherein the method comprises the following steps: Heating the multi-element alloy steel ingot to a forging temperature and preserving heat so as to carry out multidirectional upsetting forging treatment on the multi-element alloy steel ingot to obtain a preliminary deformed blank; and after the preliminary deformed blank is air-cooled to room temperature, carrying out high-temperature homogenizing di