High-strength low-yield-ratio steel as well as preparation method and application thereof

Abstract

The invention particularly relates to high-strength low-yield-ratio steel as well as a preparation method and application thereof, and belongs to the technical field of steel smelting. The high-strength low-yield-ratio steel comprises the following chemical components, in percentage by mass, of 0.055%-0.065% of C, 0.10%-0.30% of Si, 1.80%-2.10% of Mn, smaller than or equal to 0.008% of P, smallerthan or equal to 0.0015% of S, 0.02%-0.04% of Alt, 0.07%-0.08% of Nb, 0.010%-0.020% of Ti, 0.20%-0.50% of Ni, 0.15%-0.30% of Cr, 0.15%-0.30% of Cu, 0.15%-0.30% of Mo, and the balance Fe and inevitableimpurity elements. The high-strength low-yield-ratio steel has the following properties that the tensile strength is 760-800 MPa, the yield ratio is 0.70-0.75, the Charpy impact energy with the toughness of -40 DEG C is greater than or equal to 400 J, the dynamic load fatigue resistance is excellent, and the Charpy impact shear area at -40 DEG C is greater than or equal to 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 ...

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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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