Accurate heat treatment quenching technology of powder metallurgy high-speed steel precise part

Abstract

The invention provides an accurate heat treatment quenching technology of a powder metallurgy high-speed steel precise part and belongs to the field of heat treatment of high-speed steel materials. The accurate heat treatment quenching technology is provided for the precise part made of a high-speed steel ASSAB ASP23 material imported from Sweden and comprising the main alloy ingredients of 1.28%of C, 4.2% of Cr, 6.4% of W, 5.0% of Mo and 3.1% of V. According to the accurate heat treatment quenching technology, based on different workpiece hardness requirements, different quenching temperatures are adopted, so that a small designed hardness difference needed by two interactional precise parts can be achieved; different temperature keeping times are adopted for different workpiece thicknesses, so that the hardenability of the material is reliably guaranteed, the crystal structure in the material can be accurately controlled to be refined, uniform and stable, and the parts can be good in wear resistance, long in service life, high in reliability and stable in dimension and meets the use demands for the precise parts. The accurate heat treatment quenching technology comprises the technical scheme that (1) workpieces with the thickness difference smaller than 5 mm are placed in a quenching furnace and preheated to 150 DEG C in two steps; (2) the workpieces are heated to the quenching temperature T in three steps and keep the temperature for the time t in the quenching furnace; (3) the workpieces are discharged from the furnace and air cooled to 50-70 DEG C; (4) the workpiecesare fed into a tempering furnace to be heated to 550 DEG C for tempering and keep the temperature for the time of t three times, and then the workpieces are discharged from the tempering furnace and air cooled (please refer to the figure 1).

Description

technical field [0001] The invention belongs to the field of heat treatment of high-speed steel materials, and in particular relates to a precise heat treatment and quenching process for precision parts of powdered high-speed steel materials. Background technique [0002] With the upgrading of China's manufacturing industry, some precision equipment has more and more stringent requirements for parts and components. Domestic materials cannot meet their requirements in some aspects of performance, so relevant advanced imported materials have to be used; ASSAB ASP23 is a Swedish brand, and its main alloy The composition is 1.28%C 4.2%Cr 6.4%W 5.0%Mo 3.1%V Similar to American AISI M3-2 China's W6Mo5Gr4V2 high-speed steel has high purity, fine grain, uniform structure, high hardness and wear resistance after heat treatment Good, can withstand large impact loads, often used in the manufacture of machine tool tools, die-edge parts, commonly used quenching temperature 1200 ° C, hard...

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Problems solved by technology

[0002] With the upgrading of China's manufacturing industry, some precision equipment has more and more stringent requirements for parts and components. Domestic materials cannot meet their requirements in some aspects of performance, so relevant advanced imported materials have to be used; ASSAB ASP23 is a Swedish brand, and its main alloy The composition is 1.28%C 4.2%Cr 6.4%W 5.0%Mo 3.1%V Similar to American AISI M3-2 China's W6Mo5Gr4V2 high-speed steel has high purity, fine grain, uniform structure, high hardness and wear resistance after heat treatment Good, can withstand large impact loads, often used in the manufacture of machine tool tools, die-edge parts, commonly used quenching temperature 1200 ° C, hardness HRC62-HRC66; because of its high carbon and high chromium, its thermal conductivity is poor, and the thickness of the workpiece and the composition of the alloy also affect the heat treatment process. The impact is relatively large, resulting in complex heat treatment process, such as improper heat treatment, it is not only difficult to exert its excellent performance, but also difficult to control the quality, and it is easy to be scrapped in batches; for this reason, the inventor also applied for a heat treatment quenching process patent for powder high-speed steel punching die knife edge parts (Application No. 2017112175528), achieved good results;

[0003] In such as semiconductor packaging equipment, the convex mold and concave mold parts in the chip cutting and shaping mold are made of ASSAB ASP23 powdered high-speed steel material. In addition to high hardness, good wear resistance, stable size, long life and high reliability, It is also required that the two parts have a small hardness difference; but the thickness of the parts is different, and the thermal conductivity of the high-speed steel material is poor. It is not only difficult to accurately and reliably control the quenching hardness of the stainless steel by adopting a general stainless steel heat treatment process, but also difficult to reliably ensure its hardenability. Accurately control the change of crystal phase structure inside the material. The holding time during the heat treatment process of workpieces with different thicknesses is usually estimated according to the empirical formula t=αКН based on the thickness of the workpiece. It is difficult to reliably guarantee its hardenability and accurately control the crystal phase inside the material. The uniformity and stability of the structure; this requires precise heat treatment temperature and time process parameters according to different workpiece thicknesses and different hardness requirements to reliably ensure its hardenability, accurately control the internal structure changes of the material, and eliminate residual Stress, to achieve precise part hardness and no creep during use, maintaining dimensional stability

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