High-temperature, high-strength and low-carbon hot work die steel and preparation method thereof

Abstract

The invention discloses hot work die steel capable of being used for a long term at the working condition of 600-700 DEG C and belongs to the field of material and preparation. The hot work die steelcomprises the following components in percentage by mass: 0.12-0.30 of C, equal to or less than 0.5 of Si, equal to or less than 0.5 of Mn, 1.0-3.0 of Cr, 1.5-2.5 of Mo, 0.3-1.2 of W, 0.5-1.6 of Ni, 0.2-1.0 of V, 0.03-0.15% of Nb, equal to or less than 0.05 of N, equal to or less than 0.03 of S, equal to or less than 0.03 of P, equal to or less than 3.5 of (Mo+W), equal to or less than 1.0 of (Nb+V) and the balance of Fe and unavoidable impurity elements. According to the hot work die steel, low carbon is adopted to form lath martensite so as to obtain high tenacity at room temperature and lowtemperature; through alloying of Cr, W, Mo, V, Nb and the like and the thermal deformation optimization and thermal treatment technology, solution strengthening is improved and MC and M2C type carbide still keeping stability at 600-700 DEG C is formed so as to obtain high temperature strength and thermal stability of the material. Compared with the commonly used hot work die steel at present including H13, 25Cr3Mo3NiNbZr and the like, the high temperature strength at 700 DEG C of the hot work die steel is improved by 50-100%, the tempering thermal stability is improved by 50-100%, the problemabout hot work die steel used at 600-700 DEG C is better solved, and the hot work die steel has longer service life at 600 DEG C and below.

Description

technical field [0001] The invention belongs to the field of materials and preparation, and in particular relates to low-carbon hot work die steel and a preparation method thereof. Background technique [0002] Hot mold steel is mainly used for molds used in various high temperature conditions, and special components under high temperature. Hot work die steel is divided into hot forging die, hot extrusion die, die casting die and hot blanking die. Among them, the working conditions of hot forging die and hot extrusion die are the most typical. Under a certain degree of load, the red-hot solid metal is plastically deformed. As high as 500°C-600°C, the local temperature is even as high as 700°C, and it bears a certain load. Under the periodic impact of strong load, it is easy to soften, collapse, and deform. Another important performance parameter. [0003] H13 steel is a commonly used traditional mold material and has a large domestic demand. However, with the rapid develo...

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Problems solved by technology

[0007] However, the above-mentioned new hot die steel is still not suitable for high-temperature working conditions above 600°C. When the working temperature is higher than 600°C, its high-temperature strength and thermal stability will drop sharply, resulting in a sharp decline in the service life of the mold.

The reason is that when the temperature rises above 600 °C, the coherent relationship between the matrix and the second phase is destroyed, and part of the strengthening effect of M 2 C-type carbides dissolve back, and some Cr carbides have poor thermal stability and grow rapidly, which makes the high-temperature strength and red hardness of the material decrease rapidly

In order to improve the high-temperature stability of the material matrix and the second phase, the method of increasing the carbon content and alloy element content is usually used, but due to the increase in the carbon content and alloy element content, it is easy to cause the formation of acicular martensite and the formation of carbides. Coarsening, which will seriously affect the toughness and fatigue properties of hot work die steel, and is also not conducive to the service life of the die

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