High-strength thick steel plate with excellent crack-arrest property and manufacturing method thereof

Abstract

The invention relates to a high-strength thick steel plate with an excellent crack-arrest property. The steel plate has the following characteristics: a wide-plate tensile value Kca for determining the crack-arrest property is larger than 6000 N/mm<1.5>; yield strength at the positions, which are respectively 1/4 and 1/2 the thickness of the steel plate away from the surface of the steel plate, isno less than 460 MPa; tensile strength is 570 to 720 MPa; Charpy impact energy at minus 40 DEG C is no less than 200 J; and a zero-ductility transition temperature is less than minus 60 DEG C. The steel plate provided by the invention comprises the following components by weight: 0.04 to 0.16% of C, 0.1 to 0.5% of Si, 0.9 to 1.6% of Mn, 0.1 to 0.3% of Cu, 0.2 to 0.9% of Ni, no more than 0.02% ofP, no more than 0.02% of S, 0.01% to 0.05% of Als, 0.002 to 0.010% of N, 0.02% to 0.05% of Nb and 0.01 to 0.03% of Ti, with the balance being Fe and unavoidable impurities. According to the invention,through optimization of chemical components of a high-strength steel plate and adoption of controlled rolling and controlled cooling processes for controlling the microscopic structure and grain sizein a plate thickness direction, the crack-arrest steel plate with high yield and stable strength and toughness is obtained. The high-strength thick steel plate provided by the Invention is used as container vessel steel, and has the characteristics of excellent crack-arrest toughness, high yield strength, excellent low-temperature toughness and large thickness.

Description

technical field [0001] The invention relates to the field of metal material preparation, in particular to a high-strength thick steel plate with excellent crack arrestability and a manufacturing method thereof. Background technique [0002] With the advancement of super-large container ships, the maximum loading capacity of the previous few years has been advanced from 10,000 TEU to the current 20,000 TEU, which requires that the structural members of the ship (hatch coaming and hatch coaming roof) continue to thicken and the strength is further improved. More importantly, in order to suppress the brittle fracture of structural members, it is required to have the ability to suppress the growth of brittle cracks, that is, crack arrestability (performance to stop the growth of brittle fractures). However, for high-strength thick plate steel with a thickness of more than 50 mm, it is difficult to guarantee excellent crack arrest performance, excellent toughness and high strengt...

AI Technical Summary

Problems solved by technology

However, this technology ignores that thick plate steel needs the combination of bainite and ferrite to achieve excellent crack arrest performance, and the toughness and strength of the 1 / 2 position in the thickness direction are not explained, and the uniformity of the thickness direction performance cannot be guaranteed.

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