Low-temperature steel bar and production method thereof

Abstract

The invention discloses a low-temperature steel bar and a production method thereof. The low-temperature steel bar comprises the following chemical components in percentage by mass: 0.8-0.9% of Ni, 1.6-1.7% of Mn, 0.3-0.4% of Si, 0.04-0.08% of C, 0.01-0.02% of Al, less than or equal to 0.007% of P, less than or equal to 0.004% of S, less than or equal to 0.002% of O, less than or equal to 0.003% of N, less than or equal to 0.005% of As, less than or equal to 0.0002% of H and the balance of Fe and inevitable impurities. The production method thereof comprises the steps of KR molten iron pretreatment, converter smelting, LF furnace refining, RH furnace refining, continuous casting and steel rolling. According to the steel bar and the production method thereof, component design and mass production of the low-temperature steel bar are completed at low cost, and the effects of strictly controlling impurity elements, inclusions and surface quality and reducing low-temperature brittleness are achieved.

Description

technical field [0001] The invention relates to the technical field of iron and steel materials, in particular to a low-temperature steel bar and a production method thereof. Background technique [0002] Liquefied Natural Gas (LNG) storage tanks are small in size and generally consist of two inner and outer tanks. The inner tank is generally welded by low-temperature steel plates containing 9% nickel alloy steel, and the outer tank is a composite multi-layer concrete For the structure, the concrete structure of the outer tank wall and the lower ring beam of the inner tank must use low-temperature steel bars resistant to -165°C. The existing technology improves the low-temperature performance of steel bars by adding alloy elements nickel, vanadium or titanium. Although it can reduce the low-temperature embrittlement transition temperature of steel and improve low-temperature impact toughness, due to the addition of a large number of alloy elements, the production of this typ...

AI Technical Summary

Problems solved by technology

The existing technology improves the low-temperature performance of steel bars by adding alloy elements nickel, vanadium or titanium. Although it can reduce the low-temperature embrittlement transition temperature of steel and improve low-temperature impact toughness, due to the addition of a large number of alloy elements, the production of this type of low-temperature steel bars The cost has been greatly increased, which is not conducive to market promotion, and the steel smelting and rolling process methods used are also lacking in certain rationality

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