High-performance hot-working die steel for large die-casting die and manufacturing technology of high-performance hot-working die steel

Abstract

The invention relates to high-performance hot-working die steel for a large die-casting die and a manufacturing technology of the high-performance hot-working die steel. The high-performance hot-working die steel is prepared from, by mass, 0.20%-0.30% of C, smaller than or equal to 0.40% of Si, 0.30%-0.60% of Mn, 4.10%-4.50% of Cr, 2.10%-2.30% of Mo, 0.10%-0.20% of W, 0.40%-0.80% of V, smaller than 0.01% of P, smaller than 0.005% of S, 0.02%-0.04% of Nb and the balance Fe. The manufacturing method of the die steel comprises the following manufacturing process that material mixing, smelting andcasting are conducted, and then electroslag remelting is conducted; high-temperature diffusion heat treatment is conducted, multi-directional forging hot working is conducted, and cooling controllingafter forging is conducted; secondary carbide refining heat treatment and isothermal annealing treatment are conducted; and finally quenching and tempering heat treatment is conducted. The hot-working die steel has the advantages that the hardenability, the heat stability, the impact toughness and the thermal fatigue property are superior to those of H13 steel, the hot-working die steel can be machined into a single large die-casting die with the weight reaching 5 tons or above, and the good using performance is achieved.

Description

technical field [0001] The invention belongs to the technical field of alloy steel and relates to a hot work die steel, in particular to a high-performance hot work die steel for large die-casting molds and a manufacturing process thereof. Background technique [0002] Hot work die steel is a die steel used at higher temperatures (generally higher than 500 ° C), in which the alloying elements that play high temperature thermal strength and thermal stability are usually Cr, Mo, V and other alloying elements, so the current Some of the research work is mainly on the adjustment of these alloying elements. This study found that the addition of a higher content of Mo element can improve the thermal fatigue resistance and temper softening resistance of steel, and the addition of a certain amount of W element can greatly improve the thermal stability and thermal fatigue resistance of steel, so that The service temperature of the steel is greatly increased, so it is used to manufac...

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Problems solved by technology

4Cr5MoSiV1 steel is the most widely used hot work die steel, but its high temperature strength is not very high, the general use temperature can not exceed 540 ℃, and the thermal fatigue resistance and thermal stability are not high

This manufacturing process has the following problems: 1) The size of the electroslag ingot is small, and the small ingot size reduces the yield and manufacturing capacity of the product; 2) The original structure of the electroslag ingot has a large number of large particles or large blocks of liquefied carbonization 3) The grain size of the material after forging is coarse, resulting in low impact toughness of the material after quenching and tempering, and the product grade is low, which cannot meet the market demand for large cross-section, high toughness, and high heat. The need for strong hot work die steel; 4) The hydrogen expansion annealing time after forging is long, and it is prone to flaw detection defects such as white spot cracks

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