| 摘要 |
A weldable structural steel product having TiN and ZrN precipitates, which contains, in terms of percent by weight, 0.03 to 0.17% C, 0.01 to 0.5% Si, 0.4 to 2.0% Mn, 0.005 to 0.2% Ti, 0.0005 to 0.1% Al, 0.001 to 0.03% Zr, 0.008 to 0.030% N, 0.0003 to 0.01% B, 0.001 to 0.2% W, at most 0.03% P, at most 0.03% S, at most 0.01% O, and balance Fe and incidental impurities while satisfying conditions of 1.2<=Ti/N<=2.5, 0.3<=Zr/N<=2.0, 10<=N/B<=40, 2.5<=Al/N<=7, and 6.8<=(Ti+Zr+2Al+4B)/N<=17, and having a microstructure essentially consisting of a complex structure of ferrite and pearlite having a grain size of 20 mum or less. |
