Hot work die steel, heat treatment method thereof and hot work die

Abstract

The invention relates to hot work die steel, a heat treatment method thereof and a hot work die. The hot work die steel comprises the following chemical components in percentage by weight: 4.5 to 12 percent of Ni, 0.8 to 2.1 percent of Al, 0.4 to 1.99 percent of Cu, 0.001 to 1 percent of Mn, 0.0001 to 0.1 percent of C and the balance of Fe and inevitable impurities, wherein the ratio of Al to Ni is 0.075 to 0.234. The heat treatment method comprises a hardening treatment step, specifically, when Cu is larger than or equal to 0.4% and smaller than 0.8%, the hot work die steel is heated to the temperature ranging from 560 DEG C to 650 DEG C; when Cu is larger than or equal to 0.8% and smaller than 1.5%, the hot work die steel is heated to the temperature ranging from 470 DEG C to 580 DEG C; when Cu is larger than or equal to 1.5% and smaller than or equal to 1.99%, the hot work die steel is heated to the temperature ranging from 450 DEG C to 520 DEG C; maintaining for 1-240 hours, preferably 4-24 hours, and then cooling to room temperature.

Description

technical field [0001] The invention relates to a hot work die steel, a heat treatment method thereof and a hot work die. Background technique [0002] Hot work die steel is an alloy tool steel that selectively adds different weight percentages of carbon, silicon, chromium, tungsten, molybdenum, nickel, manganese, vanadium, cobalt and other alloying elements to iron. Dies that shape materials during die casting, forging, and extrusion. In recent years, the forming technology of advanced high-strength steel plates for automobiles that can meet the requirements of automobile lightweight and safety at the same time - hot stamping technology - has put forward new requirements and challenges for die steel. [0003] The thermal conductivity of the commonly used hot work die steel at room temperature is 18~24 W / mK. Generally speaking, after a certain temperature, the thermal conductivity decreases with the increase of temperature. During service, hot work dies are usually subjec...

AI Technical Summary

Problems solved by technology

However, there are the following problems: 1). The size of the carbide is not easy to control, and the carbide with a large size deteriorates the toughness; 2). After adding Ti, it is easy to form liquid out TiN and TiC with a large size, which deteriorates the toughness; 3). The Cr element cannot be completely precipitated from the matrix in the form of carbides, and high thermal conductivity cannot be achieved; 4). Multiple tempering, the process is cumbersome, and the secondary hardening peak needs to be avoided, otherwise the material has the highest hardness but the worst toughness

On the one hand, plastic mold steel does not need and cannot meet the performance requirements of hot work mold steel; on the other hand, although Cu, Ni and Al elements are added, the ratio is not reasonable, so the thermal conductivity is not significantly improved

In addition, other elements such as Si, Cr, V, etc. will seriously reduce the thermal conductivity, so the plastic mold steel does not have high thermal conductivity

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