主权项 |
1. A steel alloy composition comprising, in weight percent:
C:0.10-0.135, Mn:0.8-1.2, P:0.012 max, S:0.002 max, Si:0.30-0.40, Cu:0.15-0.35, Ni:0.15-0.25, Al:0.02-0.05, Nb:0.015-0.030, Mo:0.06-0.09, the remainder iron and other unavoidable impurities; said composition has a CE between 0.269-0.393 and a Pcm between 0.167-0.236, wherein CE and Pcm are defined as (all elemental concentrations are in wt %):
CE=C+Mn/6+(Cu+Ni)/15+(Mo+V+Cr)/5andPcm=C+Si/30+(Mn+Cu+Cr)/20+Ni/60+Mo/15+V/10+5B said alloy having a hydrogen induced cracking (HIC) resistance such that the alloy has a Crack Length Ratio (CLR), of ≦15%, a Crack Sensitivity Ratio (CSR) of ≦5%, and a Crack Thickness Ratio (CTR); of ≦2%; said alloy further having a CVN impact energy of at least 75 ft-lb at −20 F. |