High-plasticity-toughness low-alloy ultrahigh-strength steel and preparation method

Abstract

The invention provides high-plasticity-toughness low-alloy ultrahigh-strength steel and a preparation method, and relates to the technical field of engineering materials. The high-plasticity-toughnesslow-alloy ultrahigh-strength steel comprises the following chemical components in percentage by mass: 0.30-0.43% of C, 0.50-1.60% of Mn, 0.80-2.00% of Si, 0.80-1.50% of Cr, 2.50-3.50% of Ni, 0.50-1.50% of W, 0.20-0.80% of Mo, 0.05-0.20% of V, 0.01-0.20% of Nb, not greater than 0.005% of S, not greater than 0.010% of P, not greater than 0.050% of Al, and the balance Fe. The mechanical performanceof the steel material reaches the design index; the steel material can replace G50 and DT300 steel materials in a certain field; and the steel material is higher in hardenability, and can satisfy thelarge-specification requirements on the steel material.

Description

technical field [0001] The invention relates to the technical field of engineering materials, in particular to a high-plastic-toughness low-alloy ultra-high-strength steel and a preparation method thereof. Background technique [0002] A medium-alloy ultra-high-strength steel G50 (25Si2CrNi5MoNb) for a special purpose Rm≥1660Mpa, R p0.2 ≥1380MPa, A≥10%, Z≥45%, Ak≥47J, K IC ≥105MPam 0.5 , another material is DT300 (30Si2CrNi6MoV) Rm≥1730Mpa, R p0.2 ≥1350MPa, A≥8%, Z≥40%, Ak≥60J, the strength of the two materials is different, but the characteristics are similar, with high plasticity, toughness and impact resistance, but the softening of the two materials is difficult, annealing (high temperature tempering) ) hardness is high, machining (turning) is difficult, and the cost is high and the price is high. [0003] When the size specification of the material for this application is Φ90~Φ520mm, it must have high hardenability, ultra-high strength, high plasticity and toughness...

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Problems solved by technology

[0005] (1) An ultra-high-strength steel with high hardenability and low yield ratio and its preparation method (application number: CN201610065359.6). This invention is similar to G50 and DT300 and belongs to the same type of product, but the content of alloy elements is high and the cost is high. high;

[0006] (2) A low-alloy ultra-high-strength structural steel and its preparation method (application number: CN201911074448.7), the tensile strength of the material is Rm≥2135MPa, the yield strength Rp0.2≥1430MPa, and the elongation (A)≥9 %, reduction of area (Z) ≥ 30%, impact toughness Ak ≥ 15J, the parameter values ​​of yield strength, reduction of area Z, impact toughness A ku2 are relatively low, the impact performance may not be as good as G50 and DT300, and cannot meet the above technical requirements;

[0007] (3) An ultra-high-strength and high-toughness alloy steel (application number: CN201910625665.4), the tensile strength Rm and elongation (A) of the steel material in this invention are relatively large, that is, the steel has high strength and high toughness, However, the total content of chromium, nickel and molybdenum is low, resulting in low hardenability of steel materials, which cannot meet the requirements of large-scale materials;

[0008] (4) A high-toughness, easy-spinning and easy-welding ultra-high strength (application number: CN201410613963.9), the invention has suitable strength and toughness, but the content of alloy elements is high and the cost is high

[0009] After analyzing and researching the above four patents, we found that these patented products cannot replace G50 and DT300 to manufacture parts with low cost, ultra-high strength, high toughness and large cross-section

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