Steel with tensile strength of 630Mpa for mobile-type pressure vessel 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 movable pressure vessel with a tensile strength of 630MPa and a manufacturing method thereof, belonging to the field of low-alloy steel manufacturing. Background technique [0002] Mobile pressure vessels are divided into car tankers, railway tankers and tank containers. The medium for storage and transportation of mobile pressure vessels 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 steels for mobile pressure vessels used in China are steels for normalizing pressure vessels. Compared with foreign advanced level, foreign tank truck tank materials generally adopt high-strength steel with tensile strength ≥ 610MPa. The tank wall The thickness is small, and the self-weight coefficient is correspondingly reduced, t...

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Problems solved by technology

[0005] Chinese patent publication number is the patent document of CN 1040777C, discloses a kind of chemical composition, manufacturing method and performance of the large-scale spherical tank steel of yield strength ≥ 460MPa grade, and the deficiency that it exists is to add precious alloy elements such as Cu, Nb, make Increased production costs, no mention of its weldability

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