Patent ID: 8668784
Filing Date: 2014-03-11
Classification: C21D,C22C

Abstract:
1. A steel for a welded structure, comprising the following composition: by mass %, C at a C content [C] of 0.015 to 0.045%; Si at a Si content [Si] of 0.05 to 0.20%; Mn at a Mn content [Mn] of 1.5 to 2.0%; Ni at a Ni content [Ni] of 0.73% to 1.50%; Ti at a Ti content [Ti] of 0.005 to 0.015%; O at an O content [O] of 0.0015 to 0.0032%; and N at a N content [N] of 0.002 to 0.006%, and a balance composed of Fe and unavoidable impurities, wherein, a P content [P] is limited to 0.008% or less, a S content [S] is limited to 0.005% or less, an Al content [Al] is limited to 0.004% or less, a Nb content [Nb] is limited to 0.005% or less, a Cu content [Cu] is limited to 0.24% or less, a V content [V] is limited to 0.020% or less, and a steel composition parameter P and the steel for welded structure wherein a CTOD (dc min) value in an IC zone at −60° C., which is obtained by a CTOD test of BS 5762 method, is 0.59 mm or more.