High-hardness high-toughness cold work die steel as well as preparation method thereof

Abstract

The invention relates to high-hardness high-toughness cold work die steel as well as a preparation method thereof. The high-hardness high-toughness cold work die steel comprises the following chemical components in percentage by weight: 1.025-1.055% of C, 0.85-0.90% of Si, 0.20-0.40% of Mn, less than 0.02% of P, less than 0.02% of S, 8.30-8.50% of Cr, 1.95-2.05% of Mo, 0.20-0.40% of V and the balance of Fe and inevitable impurities, wherein the elements satisfy the following relationship: C=0.1(Cr+Mo). The preparation method comprises the following steps: smelting and pouring to obtain a steel ingot which serves as a consumable electrode and is placed in an electroslag remelting device for electroslag remelting and then re-solidifying to form the steel ingot; and heating the re-solidified steel ingot to 1200-1220 DEG C and then forging, quenching and tempering to obtain the cold work die steel. The impact energy of the steel is greater than or equal to 76J and the hardness of the steel is greater than or equal to 63HRC, and the steel has relatively good hardness and toughness match.

Description

technical field [0001] The invention relates to a die steel and a preparation method thereof, in particular to a high-hardness and high-toughness cold-work die steel and a preparation method thereof. The impact energy of the cold-work die steel is ≥76J and the hardness is ≥63HRC. 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 can be lower. Generally, the temperature rise of cold work die steel will not exceed 200 ~300°...

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Problems solved by technology

Since the Cr12MoV steel forms a large number of coarse eutectic carbides distributed in a continuous network, which severely splits the matrix, it 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. 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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