| 摘要 |
By heating a steel material comprising C: 0.003 to 0.05%, Si: 0.60% or less, Mn: 0.6 to 2.0%, P: 0.020% or less, S: 0.010% or less, Cr: 0.20 to 1.5%, Nb: 0.005 to 0.05%, Al: 0.060% or less, and N: 0.001 to 0.006%, further limiting, as an impurity, Mo to 0.03% or less, having a balance of iron and unavoidable impurities, and having a weld cracking parameter P CM value defined by P CM =C+Si/30+Mn/20+Cu/20+Ni/60+Cr/20+Mo/ 15+V/10+5B of 0.22% or less, to 1000 to 1300°C in temperature, finishing the hot rolling at 800°C or more in temperature, then cooling, steel for welded structures excellent in high temperature strength and low temperature toughness can be inexpensively provided. |
