High impact toughness cold work die steel and preparation method thereof

Abstract

The invention provides high impact toughness cold work die steel and a preparation method thereof. The die steel includes the following elements, by weight percent, 0.45-0.50% of C, 0.10-0.30% of Si,0.40-0.60% of Mn, 4.80-5.30% of Cr, 2.20-2.40% of Mo, and 0.50-0.90% of V, with the balance being iron and unavoidable impurity elements. The preparation method includes smelting a steel ingot, and taking the steel ingot as a consumable electrode to perform electroslag remelting so that a liquid metal can be obtained; cooling the liquid metal to an electroslag ingot; performing forging processingafter keeping the electroslag ingot under 1190-1220 DEG C for 2-4 hours; and performing quenching and tempering in order to obtain high impact toughness cold work die steel. The alloy element component design of the cold work die steel is to suitably reduce C and Cr and increase Mo and V on the basis of Cr<12>MoV, so that eutectic carbide can be reduced and refined, grains can be refined, and goodmicrostructures can be obtained.

Description

technical field [0001] The invention relates to a high impact toughness cold working die steel and a preparation method thereof. In particular, it relates to a cold work mold material with excellent microstructure and high impact toughness. It is suitable for cold forging of precision stamping dies for cold forming, bending dies for auto parts, and hydraulic forming dies. Background technique [0002] Cold work die steel is mainly used to manufacture molds that are pressed and formed under cold (room temperature) conditions, such as cold drawing dies, cold heading dies, cold extrusion dies, embossing dies, rolling dies, etc. The working conditions of the cold work die are somewhat similar to the cutting tool, but because the processed material is deformed in the cold state, the deformation resistance is very large. Compared with cutting tool steel, cold work die steel should require higher hardenability, wear resistance and toughness, while the requirement for red hardness...

AI Technical Summary

Problems solved by technology

This network eutectic carbide severely splits the matrix, and can also be used as the crack source and crack propagation path when the die steel is broken, so that the grain boundaries of the die steel are severely brittle and the toughness is very low

And during forging, due to the restriction of the forging ratio, for large-size billets, the eutectic carbides in the core are difficult to break, so there are often band-shaped carbides segregated in the forged die steel structure, which makes the die The properties of steel appear anisotropic

Moreover, due to the presence of reticulated eutectic carbides, waste products caused by cracking and overburning are prone to occur during the forging process.

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