Steel with tensile strength being of 680MPa grade and used for large transportable pressure vessel and production method

Abstract

The invention relates to steel with the tensile strength being of the 680MPa grade and used for a large transportable pressure vessel. The steel comprises the components including, by weight, 0.10-0.20% of C, 0.10-0.50% of Si, 1.00-2.00% of Mn, not greater than 0.008% of P, not greater than 0.002% of S, 0.005-0.050% of Alt, 0.10-0.50% of Cu, 0.01-0.05% of Nb, 0.10-0.20% of V, 0.20-1.00% of Ni, 0.002-0.008% of Ca and 0.010-0.020% of N. A production method comprises the steps that molten iron pretreatment and converter smelting are performed conventionally; LF furnace external refining and RH vacuum treatment are performed in sequence; tapping and continuous casting cogging are performed; segmental hot rolling is performed; normalizing is performed; and tempering is performed. According to the steel which is subjected to component designing, inclusion control, rolling and heat treatment, the tensile strength is 680-830 MPa, KV2 under the minus 40 DEG C condition is greater than or equalto 47 J, the yield ratio ReL/Rm is smaller than or equal to 0.83, and the thickness of a steel plate is 8-30 mm; and by means of the steel, requirements of preparation of the transportable vessel withhigher performance requirements can be met, and furthermore, the self weight can be reduced by 15%.

Description

technical field [0001] The invention belongs to the field of low-alloy high-strength steel manufacturing, and relates to a high-strength pressure vessel steel and a production method thereof, specifically a steel for a large mobile pressure vessel with a tensile strength of 680MPa and a production method thereof. Background technique [0002] With the rapid development of my country's energy, petrochemical, chemical and city gas industries, liquefied gas tankers play an increasingly important role in the transportation of liquid (or gas-liquid) fuels and chemical raw materials due to their flexibility and convenience. irreplaceable role. However, before the present invention was proposed, the steel used for the tank body of liquefied gas automobile tanker had always been Q345R steel (Rm was 510MPa grade), Q370R steel (Rm was 530MPa grade) and Q420R steel (Rm was 590MPa grade) with lower strength grade, resulting in the tank The body wall thickness is relatively thick, result...

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Problems solved by technology

However, the strength level of steel used in liquefied petroleum gas tankers is relatively lo

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