TiN + CuS steel sheet has to precipitate for welded structures, and methods for producing the same, and welded structures using the same

摘要

A welding structural steel product having fine complex precipitates of CuS and TiN, in weight%, C of 0.03~0.17%, Si 0.01 to 0.05% 0.4-2 Mn of .0%, Ti of 0.005~0.2%, Al of 0.0005~0.1%, N of 0.008~0.030%, B of 0.0003 to 0.01 percent, W of 0.001~0.2%, Cu of 0.1~1.5%, P 0.03% or less, S of 0.003~0.05%, O 0.005% or less, and 1.2 ≦ Ti / N ≦ 2.5,10 ≦ N / B ≦ 40,2.5 ≦ Al / N ≦ 7,6.5 ≦ (Ti + 2Al + 4B) / N ≦ and at the same time contain inevitable impurities and balance Fe welding structural steel material characterized by having a microstructure consisting essentially of a composite structure of ferrite and pearlite which satisfies the conditions of 10 ≦ Cu / S ≦ 90 and 14, has a particle size of 20μm or less is supplied It is disclosed.