Steel plate having TiN+CuS precipitates for welded structures, method for manufacturing same and welded structure made therefrom

US6686061B2 · kind B2 · utility

Assignee

• POSCO CO., LTD · KR

Inventors

• Hong-Chul Jeong · Seojong-myeon, KR
• Hae-Chang Choi · Heunghae-eup, KR

Key dates

• Filing date: Jul 16, 2002
• Grant date: Feb 3, 2004
• Expiry date: Jul 16, 2022

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10T428/12972
• WIPO field: Materials, metallurgy
• WIPO sector: Chemistry

Abstract

A weldable structural steel product having fine complex precipitates of TiN and CuS is provided which contains, in terms of percent by weight, 0.03 to 0.17%C, 0.01 to 0.05% Si, 0.4 to 2.0% Mn, 0.005 to 0.2% Ti, 0.0005 to 0.1% Al, 0.008 to 0.030% N, 0.0003 to 0.01% B, 0.001 to 0.2% W, 0.1 to 1.5% Cu, at most 0.03% P, 0.003 to 0.05% S, at most 0.005% O, and balance Fe and incidental impurities while satisfying conditions of 1.2≦Ti/N≦2.5, 10≦N/B≦40, 2.5≦Al/N≦7, 6.5≦(Ti+2Al+4B)/N≦14, and 10≦Cu/S≦90, and having a microstructure essentially consisting of a complex structure of ferrite and pearlite having a grain size of 20 &mgr;m or less.