Steel plate

Abstract

In a steel sheet, an A value is 4.5% or less, a Pcm value is 0.25% or less, a yield strength is 460 N / mm 2 to 580 N / mm 2 , a tensile strength is 550 N / mm 2 to 670 N / mm2, a difference between a hardness at 1 / 8t, which is a 1 / 8 thickness position from a surface of the steel plate in a through-thickness direction, and a hardness at 1 / 2t, which is a 1 / 2 thickness position from the surface of the steel plate in the through-thickness direction, is 20 or less by Vickers hardness, and an average grain size at 1 / 8t is 35 µm or less.

Description

technical field [0001] The present invention relates to a high-strength thick steel plate. The steel plate is suitable for welding structures such as buildings, construction machinery, marine structures, large cranes for ships, and civil structures. The strength, that is, the yield strength is 460N / mm 2 ~580N / mm 2 , Tensile strength is 550N / mm 2 ~670N / mm 2 In addition, it has uniform characteristics along the plate thickness direction, excellent weldability, base metal toughness and welding heat-affected zone toughness, and is suitable for steel plates with a plate thickness of 80mm or more. Background technique [0002] In recent years, in welded structures such as buildings, construction machinery, marine structures, large cranes for ships, civil engineering structures, etc., the application of high-strength thick steel plates has been progressing with the increase in size of structures. [0003] In the case of applying high-strength thick steel plates to large-scale st...

AI Technical Summary

Problems solved by technology

However, there is no prior art that can ensure material uniformity in the thickness direction of a high-strength steel plate exceeding, for example, 80 mm without substantially containing alloy elements such as Cr, Mo, V, etc.

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