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Tenacity excellent high intensity steel for welding heat influenced part

A welding heat-affected, high-strength technology, applied in the field of high-strength steel, to achieve excellent HAZ toughness and excellent base metal toughness

Inactive Publication Date: 2009-06-03
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, this need cannot be met in the existing technologies for improving the toughness of the HAZ

Method used

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  • Tenacity excellent high intensity steel for welding heat influenced part
  • Tenacity excellent high intensity steel for welding heat influenced part
  • Tenacity excellent high intensity steel for welding heat influenced part

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Experimental program
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Embodiment Construction

[0036] The first point on the composition of the steel sheet of the present invention is that on the basis of extremely low C content, elements Mn, Ni, and Cu that improve hardenability are actively added in accordance with AS≧3.60 that can ensure the predetermined base metal strength, and the other On the one hand, Nb, V, and Mo are actively suppressed so that DL≦2.80 can ensure the toughness of the base material. First, the steel composition of the steel sheet according to the present invention, the resulting structure and properties after hot rolling will be described with reference to the CCT diagram.

[0037] figure 1 Shown are the CCT diagrams of the ultra-low C-series steel (A) to which Mn, Ni, and Cu are actively added in the present invention, and the conventional high-C-series steel (B1) and low-C-series steel (B2). The figure shows that BF is carbon-free bainite, GBF is granular carbon-free bainite, M is martensite, B is bainite, and F is ferrite. According to thi...

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PUM

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Abstract

The present invention provides a steel product which comprises by mass, 0.010 to 0.080% C, 0.02 to 1.00% Si, 1.10 to 2.90% Mn, 0 to 0.030% P, 0 to 0.010% S, <=0.20% Al, 0.40 to 2.40% Ni, 0.50 to 1.95% Cr, 0.16 to 1.10% Mo, 0.002 to 0.030% Ti and 0.0058 to 0.0120% N also so as to satisfy 1.0<=[Ti] / [N]<4.0, and the balance Fe with inevitable impurities, and in which AS value and DL value defined by the following formulae satisfy AS>=3.60 and DL<=2.80, and has a structure mainly composed of bainitic ferrite: AS=[Mn]+[Ni]+2*[Cu], and DL=2.5*[Mo]+30*[Nb]+10*[V]; wherein, [X] denotes the content (mass%) of the element X.

Description

technical field [0001] The present invention relates to a high-strength steel with a tensile strength above 780MPa used in bridges, buildings, ships, penstocks, tanks, and other large structures, in particular to a large A material excellent in toughness of the welded heat-affected zone (hereinafter referred to as "HAZ") after heat input welding. Background technique [0002] In the high-strength steel plate above 780MPa, from the viewpoint of ensuring the strength of the base metal, since a large amount of alloy components are added, when the cooling rate is fast under low heat input welding conditions, the HAZ is hardened, and welding cracking (low temperature cracking) is likely to occur. In order to prevent this from happening, preheat above 100°C during welding construction. If such preheating can be omitted, construction efficiency can be greatly improved and cost reduction can be realized. Therefore, a high-tensile steel sheet of 780 MPa class or higher having excel...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/50
CPCC21D8/0205C22C38/001C22C38/02C22C38/42C22C38/44C22C38/46C22C38/48C22C38/50C22C38/54C22C38/58
Inventor 高冈宏行冈崎喜臣畑野等
Owner KOBE STEEL LTD