| 摘要 |
PURPOSE:To obtain a steel material having superior notch toughness at low temp. in its weld heat-affected zone by adding specified amounts of C, Si, Mn, P, N, Al, S and B and forming a specified number of grains of Ti oxide and a composite TiN-MnS body having a specified grain size. CONSTITUTION:The composition of a steel for welding having toughness at low temp. is composed of, by weight, 0.02-0.18%C, <=0.5% S, 0.4-1.8% Mn, <=0.015% P, <=0.004% N, <=0.006% Al, 0.001-0.005% S, 0.0002-0.002% B and the balance Fe with inevitable impurities, and 5X10<4>-1X10<8> grains of Ti oxide and a composite TiN-MnS body having 0.1-3mum grain size are formed per 1mm<2> steel.
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