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steel for welding

A technology of steel and content, applied in the direction of welding medium, welding equipment, welding/cutting medium/material, etc., can solve the problems of low limit value and inability to obtain high strength, and achieve the effect of excellent fracture toughness and excellent CTOD characteristics

Inactive Publication Date: 2016-05-11
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0012] However, at this time, P CTOD and CeqH limit values ​​are low, so it is necessary to greatly limit the amount of alloy components that can be added
Therefore, it is impossible to obtain high-strength steel with a plate thickness of 6-100mm commonly used in structural materials.

Method used

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Experimental program
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Embodiment Construction

[0048] In the present embodiment, B is added to refine the microstructure of the FL portion as described above. B segregates at the prior-austenite grain boundaries to lower the grain boundary energy, thereby significantly delaying the ferrite transformation of steel. Therefore, structures such as coarse ferrite formed from grain boundaries are suppressed by the HAZ structure having coarse austenite grains. In addition, the microstructure of the FL portion becomes Significantly fine. Its purpose is to suppress the phase change at the grain boundary due to solid-solution B, and to facilitate ferrite transformation from the oxide-based non-metallic inclusions existing in the crystal grains in the form of transformation nuclei. Thereby IGF increases. In addition, since coarse inclusions become the starting point of fracture, it is necessary to reduce coarse inclusions, and fine inclusions are preferable as transformation nuclei.

[0049] In order to obtain the above effects, ...

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Abstract

A steel for welding includes steel components in which P CTOD is less than or equal to 0.065%, CeqH is less than or equal to 0.225%, FB is greater than or equal to 0.0003%, and Bp is 0.09% to 0.30%. In the steel for welding, in a thickness center portion of a cross-section in a thickness direction, the number of oxide particles having an equivalent circle diameter of 2 µm or greater is less than or equal to 20 particles / mm 2 and the number of Ti oxides having an equivalent circle diameter of 0.05 µm to 0.5 µm is 1.0×10 3 particles / mm 2 to 1.0×10 5 particles / mm 2 .

Description

technical field [0001] The present invention relates to a steel material for welding having excellent CTOD properties in welding heat-affected zones (Heat Affected Zone; HAZ) from low heat input welding (also called small heat input welding) to medium heat input welding (also called center line energy welding) and its manufacturing method , especially the FL part (welding fusion line, FusionLine), which is the boundary between WM (welding metal) and HAZ (welding heat-affected zone), and the IC part (heat-affected zone between critical temperatures), where the toughness is most deteriorated during low-heat input welding to medium-heat input welding. Intercritical HAZ) is a steel material for welding that has extremely good CTOD properties at the boundary between HAZ and BM (base metal) and exhibits excellent toughness in the welded heat-affected zone. [0002] this application claims priority based on Japanese Patent Application No. 2011-257688 for which it applied in Japan on ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/00B21B3/00B22D11/00B22D11/124C21D8/02C22C38/16
CPCC22C38/001B23K35/30B23K35/3053B23K35/3073C21D8/02C22C38/00C22C38/002C22C38/008C22C38/02C22C38/04C22C38/08C22C38/12C22C38/14C22C38/16C22C38/60
Inventor 福永和洋渡部义之臼井真介千千岩力雄
Owner NIPPON STEEL CORP