Die-casting die steel with high heat conductivity and large section and preparation and heat treatment method thereof

Abstract

The invention relates to die-casting die steel with high heat conductivity and large section and a preparation and heat treatment method thereof. The die steel is characterized by comprising the following main alloy elements by mass percent: 0.30-0.45% of C, 0.20-0.30% of Mn, 0.10-0.30% of Si, 2.00-3.50% of Cr, 2.00-6.00% of Ni, 2.50-4.00% of W, 1.00-1.50% of Mo, 0.35-0.65% of V, less than 0.025% of P, less than 0.025% of S and the balance of Fe. The steel is prepared by mixing, smelting, casting, electroslag remelting and annealing, high-temperature homogenization treatment, multi-directional forging, ultrafine treatment and final quenching and tempering heat treatment. The die steel has better heat conductivity, quenching degree, high-temperature strength and heat cracking resistance than those of H13 steel and takes a critical step for localization of steel for large, complex and precision die-casting dies in China.

Description

Technical field [0001] The invention relates to a die-casting die steel with high thermal conductivity and large section, and a preparation and heat treatment method thereof, belonging to the technical field of alloy steel manufacturing technology. Background technique [0002] Since die casting can cast parts with complex shapes, high precision, small surface roughness and good mechanical properties, the number of aluminum, zinc, copper, magnesium, lead and other alloy parts produced by die casting is increasing. develop rapidly. However, for a long time, the domestic industry has not found the best mold materials, all of which are replaced by general hot work mold steels such as H13 (4Cr5MoSiV1) and H11 (4Cr5MoSiV), but the effect is not satisfactory. On the one hand, surface micro-cracks are prone to occur during the forging process of the plate; on the other hand, the service life of the die-casting mold is very short, and the surface quality of the die-cast product is not h...

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Problems solved by technology

Because this material contains a large amount of secondary hardening elements, its tempered secondary carbides are easy to grow, coarsen and undergo type transformation under service conditions, and the alloying elements in the tempered martensite are also easy to precipitate and reduce the hardness of the steel. strength, thereby reducing the high temperature performance of steel

At the same time, due to the alloying characteristics of H13 or H11 steel, when manufacturing large-scale die steel over 350mm, the core cannot be completely hardened and cannot reach the level of high-quality steel. Serious obstacles have brought great impact on the localization of large, complex and precision die-casting molds in China

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