A kind of high-strength and high-toughness Cu-containing low-alloy high-strength steel and heat treatment method thereof

Abstract

The invention relates to the field of low-alloy high-strength steel, in particular to a high-strength and high-toughness Cu-containing low-alloy high-strength steel and a heat treatment method thereof. The chemical composition (mass percentage) of Cu-containing low-alloy high-strength steel is: C 0.035-0.070%; Ni 3.5-4.5%; Cr 0.8-1.2%; Mo 0.35-0.65%; Mn 0.25-0.65%; Si<0.05%; S≤0.010%; P≤0.010%; Nb 0.025-0.055%; Cu 1.0-2.0%, the balance being Fe. The heat treatment method includes quenching and tempering treatment, that is, the martensite structure is first obtained by quenching at 840-920°C, and then tempered at 400-600°C to obtain the tempered martensite structure. After heat treatment, it can meet the comprehensive performance requirements of Cu-containing low-alloy high-strength steel for strength, elongation and low-temperature impact toughness.

Description

technical field [0001] The invention relates to the field of low-alloy high-strength steel, in particular to a high-strength and high-toughness Cu-containing low-alloy high-strength steel and a heat treatment method thereof. Background technique [0002] Low-C and Cu-containing low-alloy high-strength steel, as a kind of steel for high-end marine equipment, has high strength, good toughness and excellent weldability, and is widely used in the construction of ships and offshore oil platforms. [0003] Compared with the traditional Fe-Cr-Ni-Mo high-strength steel, the C content in Cu-containing low-alloy high-strength steel (such as HSLA-100 alloy steel) is lower. The precipitation in the form of nano-Cu-rich clusters has a precipitation strengthening effect, thus making up for the loss of strength caused by low C. For example, after tempering at 450-500 °C, the number density of Cu-rich clusters is the largest, thereby obtaining the peak strength. Compared with the quenched ...

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Problems solved by technology

[0010] The purpose of the present invention is to provide a high-strength, high-toughness Cu-containing low-alloy high-strength steel and its heat treatment method. Through the regulation and control of Mn content and the optimization of the heat treatment system, an alloy steel with good matching of strength and toughness is obtained, which solves the problem of existing problems The problem of poor strength and toughness matching of Cu low-alloy high-strength steel can meet the safe use requirements of high-strength steel in special environments

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