Normalizing-type high-strength pressure vessel steel plate with good low-temperature toughness at minus 50DEG C and manufacturing method of normalizing-type high-strength pressure vessel steel plate

Abstract

The invention discloses a normalizing-type high-strength pressure vessel steel plate with good low-temperature toughness at minus 50DEG C. The normalizing-type high-strength pressure vessel steel plate is made of chemical compositions comprising, by weight, 0.10-0.22% of C, not more than 0.40% of Si, 1.10-1.74% of Mn, not more than 0.015% of P, not more than 0.010% of S, not more than 0.40% of Ni, not more than 0.18% of V, 0.0070-0.0190% of N, 0-0.025% of Als, 0-0.018% of Ti, the balance of Fe and unavoidable impurities, wherein formulas: 3.5</=(V+Ti)/N</=15 and Ti/(3.5N)</=C+V+2Ti</=5V/(C+V) are satisfied simultaneously. The yield strength of the steel plate is >/=460MPa, the tensile strength ranges from 630MPa to 740MPa, the ductility is >/=25%, the yield ratio is </=0.80, good welding property is achieved, and production cost is low.

Description

technical field [0001] The invention relates to the field of low-alloy steel manufacturing, in particular to a normalizing high-strength pressure vessel steel plate with good low-temperature toughness at -50°C and a manufacturing method thereof. Background technique [0002] With the rapid development of my country's economy, the demand for pressure vessels shows a trend of high-parameter development. These pressure vessels have one of two characteristics: [0003] 1) The use of advanced technologies and processes, and the diversification and deterioration of raw materials make the service conditions of pressure vessels extreme, manifested as higher pressure and lower temperature; [0004] 2) In order to improve economic benefits, pressure vessels with extreme dimensions appear, which are characterized by larger diameters, thinner wall thicknesses, and greater lengths or heights. [0005] The yield strength of micro-alloyed high-strength low-alloy steel is 2 to 3 times that...

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Problems solved by technology

[0008] The Chinese invention patent with the publication number CN 95104993.3 discloses a large-scale spherical tank steel composition and heat treatment method, the chemical composition, manufacturing method and performance of large-scale spherical tank steel with yield strength ≥ 460MPa. The disadvantage is that too much Precious alloying elements such as Cu and Nb, which increase the production cost, did not mention its welding performance, and did not see its introduction to the metallographic structure of the finished steel plate

[0009] The Chinese invention patent with the publication number CN103233160A discloses a normalized high-strength steel plate with a yield strength of 460 MPa and its manufacturing method, but its tensile strength range is ≥ 570 MPa, which is lower than the strength level of the steel of the present invention, and it does not mention And the actual weldability and welding performance of the steel, and the ferrite pearlite structure of the steel has obvious banded structure, the banded structure will make the properties of the steel plate have greater anisotropy, and damage the low temperature fracture toughness of the steel

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