Bainite pre-hardening plastic mold steel and preparation method and heat treatment method thereof

Abstract

The invention relates to bainite pre-hardening plastic mold steel and a preparation method and a heat treatment method thereof. Chemical components of the steel are optimized on the basis of P20 steel, the content of manganese (Mn) is appropriately increased, the content of the chromium (Cr) and molybdenum (Mo) is reduced, little niobium (Nb) is added, and no nickel (Ni) and vanadium (V) in expensive price are not contained. The preparation method of the plastic mold steel comprises the following steps of: compounding, smelting and casting; carrying out the multi-directional forging heat machining; carrying out the wind cooling and the air cooling; and finally carrying out the tempering heat treatment. The plastic mold steel has characteristics of large cross section, low cost, high hardenability, good hardness uniformity and the like and also has low susceptibility of flake formation, a diffusion hydrogen annealing process is omitted, in addition the post-forging normalizing is adopted to substitute a thermal refining process, so that the production period is greatly shortened, the domestication of the plastic mold steel with large cross section, long service life, top quality and short period can stride forward for a large step, and the existing domestic manufacturing concept of energy conservation, emission reduction, sustainability and economical type can be met.

Description

technical field [0001] The invention relates to a bainitic pre-hardened plastic mold steel and a preparation and heat treatment method thereof, belonging to the technical field of alloy steel manufacturing technology. Background technique [0002] The so-called pre-hardened plastic mold steel is pre-heat-treated by the steel factory in the supply state to make it reach the required hardness and performance when the mold is used, so as to avoid quenching and tempering after mold processing Oxidation, decarburization, deformation and cracking caused by heat treatment operations, thus ensuring the manufacturing accuracy of the mold. At the same time, because heat treatment and finishing after heat treatment are omitted, the cost is reduced and the manufacturing cycle is greatly shortened. [0003] Pre-hardened plastic mold steel belongs to low and medium carbon steel, the carbon content is generally in the range of 0.3% to 0.5%, and alloy elements such as Cr, Mo, Mn, Ni, V are...

AI Technical Summary

Problems solved by technology

3Cr2Mo (P20) is currently the most widely used, generally used to make plastic modules with a thickness of less than 400mm, while 3Cr2MnNiMo (718) steel is based on P20 by adding elements such as Ni, Cr, etc. to improve hardenability, which can be used It is suitable for making modules with a cross-sectional thickness of up to 1000mm, but the addition of 1% Ni content makes the cost significantly higher than that of P20

[0006] Therefore, quenched and tempered pre-hardened plastic mold steel has long production cycle, high energy consumption and high cost, while some non-quenched and tempered steel used for structural parts is introduced to manufacture plastic mold steel, and its structure is mostly ferrite- pearlite type

This not only makes many production enterprises lack international and domestic competitiveness, but also causes a lot of waste of resources in our country.

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