High-tenacity low-alloy high-strength steel and quenched-tempered heat treatment method thereof

Abstract

The invention provides high-tenacity low-alloy high-strength steel and a quenched-tempered heat treatment method of the steel. Chemical components of the low-alloy high-strength steel comprise, by mass, 0.23% to 0.35% of C, 0.20% to 0.35% of Si, 1.0% to 4.0% of Ni, 0.8% to 1.2% of Cr, 0.4% to 1.0% of Mn, 0.4% to 1.0% of Mo, 0.01% to 0.12% of V, <=0.010% of S, <=0.010% of P, and the balance Fe. The quenched-tempered heat treatment method comprises the following steps: the steel is normalized under the temperature of 850 DEG C to 900 DEG C, then the steel is quenched under the temperature of 830 DEG C to 920 DEG C so as to form martensite, at last, tempering treatment is conducted on the martensite under the temperature between 590 DEG C and 660 DEG C so as to obtain a tempered martensite structure. The low-alloy high-strength steel after quenched-tempered treatment can satisfy the requirements of the low-alloy high-strength steel to the comprehensive performance such as tenacity, yield ratio, low temperature impact toughness and elongation.

Description

technical field [0001] The present invention relates to low-alloy high-strength steel, and specifically provides a low-alloy high-strength steel with high toughness at low temperature and a heat treatment method thereof. Tempered sorbite is obtained by adjusting the alloy composition and undergoing appropriate quenching and tempering treatment. Microstructure, on the basis of ensuring the high strength of steel, high low temperature impact toughness can be obtained. Background technique [0002] With the development of society and the progress of science and technology, steel has been used in various fields of society. At the same time, people have put forward higher requirements for the quality of steel. Low-alloy high-strength steel, because of its high strength, good plasticity and toughness, has been widely used in defense fields such as aerospace and ships, and it is also used in other civil fields such as pressure vessels, fire protection, medical treatment, petroleum ...

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Problems solved by technology

[0010] The strength and toughness of the low-alloy high-strength steel disclosed in the above patents cannot be achieved at the same time. At the same time, the yield ratio is not considered as a key consideration, because the general low-alloy high-strength steel has a relatively high yield ratio, which seriously affects the safety of high-strength steel.

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