welded joint

Abstract

A weld joint with an excellent CTOD property is produced with a weld metal, using a steel plate as a base metal. The steel plate has a chemical composition including C: 0.03% to 0.09%, Si: 0.01% to 0.35%, Mn: 1.3% to 2.0%, P: 0.012% or less, S: 0.0035% or less, Al: 0.01% to 0.06%, Ni: less than 0.3%, Mo: less than 0.10%, Nb: 0.005% to 0.023%, Ti: 0.005% to 0.025%, B: less than 0.0003%, N: 0.002% to 0.005%, Ca: 0.0005% to 0.0050%, and O: 0.0030% or less, with the components additionally satisfying a predetermined relationship. The weld metal has a chemical composition including C: 0.040% to 0.090%, Si: 0.1 % to 0.8%, Mn: 1.0% to 2.5%, Al: 0.020% or less, Ni: 0.1 % to 1.0%, Mo: 0.05% to 0.50%, Ti: 0.005% to 0.050%, and B: 0.0015% or less, the balance being Fe and incidental impurities.

Description

technical field [0001] The present invention relates to a welded joint using a high-tensile steel plate used for steel structures such as marine structures, wind power generation, ships, pressure vessels, and pressure water pipes as a base material. A high-tensile steel sheet having excellent low-temperature toughness at the welded portion at the time of welding is used as a base material, and a welded joint is produced through a weld metal having excellent toughness. Background technique [0002] Steel used in ships, marine structures, wind power generation equipment, and pressure vessels is welded and joined, and finished into structures of desired shape. Therefore, from the viewpoint of the safety of structures, these steels are required to have high strength and excellent toughness of the base metal, as well as excellent toughness of the welded joint (weld metal, weld heat-affected zone). [0003] As a criterion for evaluating the toughness of steel, the absorbed energy...

AI Technical Summary

Problems solved by technology

However, depending on the welding conditions, the addition of B may lead to the formation of hard phases such as martensite, which may worsen the toughness

Images