High-strength thick steel plate having excellent arrestability

A thick steel plate, high-strength technology, applied in the field of high-strength thick steel plate, to achieve the effect of excellent crack arrest and high strength

Active Publication Date: 2014-07-30
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the above-mentioned crack arrestability generally tends to be opposite to the strength and plate thickness.

Method used

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  • High-strength thick steel plate having excellent arrestability
  • High-strength thick steel plate having excellent arrestability
  • High-strength thick steel plate having excellent arrestability

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0192] The effects of the present invention will be described below based on examples.

[0193] In the steelmaking process, the component composition of molten steel was adjusted, and thereafter, steel sheets A to Z were produced by continuous casting. Steel sheets A to O are invention steels, and steel sheets P to Z are comparative steels.

[0194] In Examples 1 to 20 and Comparative Examples 21 to 55, the steel sheets A to Z were reheated and then plate rolled to form thick steel plates with a thickness of 60 to 95 mm, and then the steel plates were water cooled. However, in Comparative Example 53, air cooling was performed instead of water cooling. Thereafter, heat treatment is performed as necessary.

[0195] Table 1 and Table 2 show the component compositions of the steel sheets A to Z. Underlines in Table 1 and Table 2 indicate that the values ​​are outside the scope of the present invention, and italics indicate the analysis values ​​of the amounts contained as unavo...

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Abstract

This high-strength thick steel plate has a component composition in which the carbon equivalent (Ceq) is 0.3-0.5% and has a microstructure containing 70% or less of ferrite by area ratio and 30% or more of bainite by area ratio. At 1/4 of the plate thickness, the crystal grain boundary density, which is the total length per unit area of crystal grain boundaries having a crystal orientation difference of 15 DEG or greater, is 400-1000 mm/mm2; and the area ratio of the {100} plane, which forms an angle within 15 DEG with respect to a plane that is perpendicular to the main rolling direction, is 10-40%. At 1/2 of the plate thickness, the crystal grain boundary density is 300-900 mm/mm2; and the area ratio of the {110} plane, which forms an angle within 15 DEG with respect to a plane that is perpendicular to the main rolling direction, is 40-70%.

Description

technical field [0001] The present invention relates to a high-strength thick steel plate excellent in crack arrestability. [0002] This application claims priority based on Patent Application No. 2012-087384 for which it applied in Japan on April 6, 2012, and uses the content here. Background technique [0003] For heavy steel plates used in structures such as shipbuilding, buildings, tanks, marine structures, and line pipes, in order to suppress brittle fracture of the structure, the ability to suppress the propagation of brittle fractures, that is, crack arrest performance (brittle fracture propagation stop performance) is required. In recent years, along with the increase in the size of structures, there have been more and more cases of using high-strength thick steel plates with a yield stress of 390 to 690 MPa and a plate thickness of 60 to 95 mm. However, the aforementioned crack arrestability generally tends to be opposite to each of the strength and plate thicknes...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C22C38/58C21D8/02
CPCC21D8/02C21D8/0247C21D2201/05C21D2211/002C21D2211/005C22C38/001C22C38/002C22C38/005C22C38/02C22C38/06C22C38/42C22C38/44C22C38/46C22C38/48C22C38/50C22C38/52C22C38/58
Inventor 中岛清孝大川铁平
Owner NIPPON STEEL CORP
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