Good low-temperature high-toughness normalized high-strength pressure vessel steel plate and manufacturing method thereof

Abstract

The present invention discloses a good low-temperature high-toughness normalizing type high-strength pressure container steel plate, wherein the chemical components comprise, by weight, 0.10-0.22% of C, less than or equal to 0.40% of Si, 1,10-1.80% of Mn, less than or equal to 0.015% of P, less than or equal to 0.010% of S, less than or equal to 0.40% of Ni, less than or equal to 0.035% of Nb, less than or equal to 0.17% of V, 0.0070-0.0190% of N, 0-0.025% of Als, 0-0.018% of Ti, and the balance of Fe and unavoidable inclusion, wherein (V+Ti+Nb) / N is more than or equal to 3.5 and is less than or equal to 15, and (C+V+2Ti) is more than or equal to Ti+Nb / (3.5N) and is less than or equal to 5V / (C+V+Nb). The good low-temperature high-toughness normalizing type high-strength pressure container steel plate has the following characteristics that: the yield strength is more than or equal to 460 MPa, the tensile strength is 630-725 MPa, the elongation is more than or equal to 25%, the yield ratio is less than or equal to 0.85, the weldability is good, and the production cost is low.

Description

technical field [0001] The invention relates to the field of low-alloy steel manufacturing, in particular to a normalized high-strength pressure vessel steel plate with good low-temperature high toughness 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 of h...

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Problems solved by technology

[0008] The Chinese invention patent with the publication number CN 95104993.3 discloses the chemical composition, manufacturing method and performance of a large spherical tank steel with yield strength ≥ 460MPa. It increases the production cost, does not mention its welding performance, and does 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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