High-toughness low-yield ratio low-temperature steel for LPG ship storage tank and manufacturing method thereof

Abstract

The invention belongs to the field of manufacturing of low alloy steel, and particularly relates to high-toughness low-yield ratio low-temperature steel for an LPG ship storage tank and a manufacturing method thereof. The low-temperature steel comprises the following raw material chemical components by mass percent: 0.08% to 0.23% of C, 0.30% or less of Si, 0.85% to 1.50% of Mn, 0.004% or less ofP, 0.002% or less of S, 0.015% to 0.050% of Alt, 1.00% to 1.30% of Ni and 0.004% or less of N, and further comprises at least one of 0.10% or less of Mo, 0.05% or less of Nb, 0.036% or less of Ti and0.005% or less of Ca, and the balance being Fe and unavoidable impurities. The method for manufacturing the low-temperature steel comprises a steel-making technology, a steel rolling technology and aprocessing and thermal treatment technology. According to the high-toughness low-yield ratio low-temperature steel, through component design, inclusion control, rolling and thermal treatment, a steelplate has excellent low-temperature toughness and good welding performance, the yield ratio is relatively low, the steel plate can be utilized to manufacture the storage tank for an LPG ship, and utilization safety performance is greatly improved.

Description

technical field [0001] The invention belongs to the field of low-alloy steel manufacturing, and in particular relates to a low-temperature steel with high toughness and low yield ratio for LPG ship storage tanks and a manufacturing method thereof. Background technique [0002] The yield ratio is the ratio of the yield strength to the tensile strength of the material. A steel with a lower yield ratio can improve the deformation resistance of the steel under severe load deformation, that is, the lower the yield ratio, the material from plastic deformation to The greater the deformation energy required for fracture, the greater its ability to resist large deformations and effectively ensure safety. However, in the application of LPG ship and LPG storage tank materials, the service temperature has reached -80°C, not only the yield ratio of the material is strictly regulated, but also the low temperature toughness of the steel is extremely high. Therefore, it is necessary to reas...

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Problems solved by technology

[0004] In order to overcome the defects of the prior art, the purpose of the present invention is to provide a low yield ratio, high strength, high toughness low-temperature pressure vessel steel for LPG ship storage tanks and its manufacturing method, which can overcome the yield ratio of existing steel types High, low temperature toughness and poor yield strength ratio matching problem, using a feasible production process, suitable for large-scale production operations, to obtain good low temperature toughness, tensile properties of pressure vessel steel

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