Steel for portable pressure vessel with tensile strength of 630mpa and production method thereof

Abstract

The invention provides steel with the tensile strength of 630Mpa for a mobile-type pressure vessel. The steel is produced by using one or a mixture of more than two of the following chemical components in percentage by weight: 0.15-0.20% of C, 0.15-0.40% of Si, 1.00-1.70% of Mn, less than or equal to 0.015% of P, less than or equal to 0.006% of S, 0.10-0.30% of Ni, 0.02-0.20% of V, 0.03-0.3% of Cu, or 0.01-0.10% of Cr or 0.008-0.020% of Ti. A production method of the steel comprises the following steps: continuously casting so as to form billet, heating, carrying out hot rolling, and carrying out thermal treatment by adopting a normalizing technology. The yield strength of the steel is greater than or equal to 460Mpa, the tensile strength of the steel is 630-730Mpa, the elongation of the steel is greater than or equal to 25%, the yield ratio of the steel is less than or equal to 0.80, and the steel has good welding properties. The hardening capacity of the steel subjected to heat and hot machining is not obvious. The steel has low requirements on welding wire energy, welded joints have good mechanical properties, and the steel lays a foundation for the enlargement and weight reduction of the mobile-type pressure vessel and is relatively low in production cost.

Description

technical field [0001] The invention relates to a steel for a mobile pressure vessel with a tensile strength of 630 MPa and a manufacturing method thereof, belonging to the field of low-alloy steel manufacturing. Background technique [0002] Mobile pressure vessels are divided into automobile tankers, railway tankers and tank containers. The medium of mobile pressure vessel storage and transportation is liquefied gas, cryogenic liquid and permanent gas, such as liquefied petroleum gas, ethylene oxide, liquid oxygen, liquid ammonia, liquid carbon dioxide, liquefied natural gas, compressed natural gas, hydrogen, etc. [0003] At present, most of the steel used for mobile pressure vessels in China is normalized pressure vessel steel. Compared with foreign advanced level, foreign tank car body materials generally use high-strength steel with tensile strength ≥ 610MPa. The thickness is smaller, and the self-weight coefficient is correspondingly reduced, thereby improving the se...

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Problems solved by technology

[0005] The Chinese Patent Publication No. is the patent document of CN1040777C, discloses the chemical composition, manufacturing method and performance of a kind of large spherical tank steel with yield strength ≥ 460MPa grade. Increased cost, no mention of its welding performance

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