Nickel-added high-polishing pre-hardened plastic mold steel plate and production method thereof

Abstract

The invention discloses a nickel-added high-polishing pre-hardened plastic mold steel plate and a production method thereof. The steel plate is prepared from the chemical components of, by mass, 0.39-0.45% of C, 0.80-1.00% of Mn, 0.20-0.40% of Si, less than or equal to 0.015% of S, less than or equal to 0.020% of P, 0.90-1.10% of Cr, 0.15-0.25% of Mo, 0.40-0.60% of Ni, 0.005-0.030% of Al, and thebalance being iron and unavoidable impurities. The production method includes the processes of converter smelting, LF furnace refining, RH vacuum refining, continuous casting slab, controlled rollingand controlled cooling and high temperature tempering heat treatment. Through the component design of adding nickel and the processes of controlled rolling and controlled cooling and high temperaturetempering heat treatment, pre-hardened plastic mold steel is obtained, and the steel has the characteristics of excellent polishing performance and simple production processes.

Description

technical field [0001] The invention belongs to the technical field of plastic mold steel, and in particular relates to a nickel-added high-polishing pre-hardened plastic mold steel plate and a production method thereof. Background technique [0002] As an industrial raw material for the manufacture of plastic and rubber products, plastic mold steel is widely used in various industries such as household appliances, electronic communication equipment, living utensils, and vehicles. This type of die steel is generally delivered in a pre-hardened state, and the hardness is controlled between 28 and 36HRC. From the perspective of raw material cost, domestic 42CrMo, Japanese SCM440, American AISI 4140 and other brands are gradually introduced into the field of plastic mold steel due to their good economy. The mold steel plate standard YB / T 107 is low in SM3Cr2Mo, and its hardness is close to the use requirements of plastic mold steel. [0003] Since the hardenability of plastic...

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Problems solved by technology

[0003] Since the hardenability of plastic mold steel with low alloy composition such as 42CrMo is weaker than that of SM3Cr2Mo, there are quality problems such as low hardness in the core and large difference in hardness from the surface after quenching. It is difficult to meet the target that the hardness deviation of the entire steel plate does not exceed 3HRC. The greater the thickness, the more obvious the uneven hardness. When the thickness exceeds 50mm, the original 42CrMo composition is difficult to meet the hardness requirements for plastic mold steel.

In addition, after the alloy elements are reduced, the polishing performance of the mold steel is reduced, and it cannot meet the technical requirements of the polished mirror surface of plastic mold steel such as P20 (SM3Cr2Mo) reaching more than 2000 mesh.

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