A kind of high-strength low-yield ratio steel and its preparation method and application

Abstract

The invention specifically relates to a high-strength low-yield-ratio steel and its preparation method and application, belonging to the technical field of steelmaking. The high-strength low-yield ratio steel provided by the invention, in terms of mass fraction, has a chemical composition comprising: : C: 0.055~0.065%, Si: 0.10~0.30%, Mn: 1.80~2.10%, P: ≤0.008%, S: ≤0.0015%, Alt: 0.02~0.04%, Nb: 0.07~0.08%, Ti: 0.010~0.020%, Ni: 0.20~0.50%, Cr: 0.15~0.30%, Cu: 0.15~0.30%, Mo: 0.15~0.30%, the balance is Fe and unavoidable impurity elements; the high strength provided by the present invention Low yield ratio steel with the following properties: tensile strength of 760-800MPa, yield ratio of 0.70-0.75, toughness of ‑40°C Charpy impact energy ≥ 400J, and excellent dynamic fatigue resistance, ‑40 ℃ Charpy impact shear area ≥ 90%.

Description

technical field [0001] The invention belongs to the technical field of steel smelting, and in particular relates to a high-strength low-yield ratio steel and its preparation method and application. Background technique [0002] The low yield ratio steel refers to the steel whose yield ratio, that is, the ratio of yield strength Rel to tensile strength Rm (Rel / Rm) is significantly lower than that of conventional steel. A lower yield ratio means a higher work hardening index. The yield ratio of steel is an important mechanical performance index related to the safety of the structure, which seriously affects the following aspects: 1. The deformation capacity and limit of the frame structure Bearing capacity, 2. Safety of welded structure, 3. Safety of continuous beam structure, etc. [0003] Low yield ratio steel is often used in bridges, buildings, pipelines, offshore platforms and other facilities. With the continuous improvement of technology level, higher requirements are ...

AI Technical Summary

Problems solved by technology

[0003] Low yield ratio steel is often used in bridges, buildings, pipelines, offshore platforms and other facilities. With the continuous improvement of technology level, higher requirements are put forward for the strength, toughness and welding performance of steel. Compared with steel, it cannot meet the properties of high strength, high toughness, low yield ratio, high fatigue resistance, high dimensional accuracy and excellent welding performance at the same time

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