Steel Material

Abstract: Provided is a steel material having both high strength of at least 125 ksi and excellent low-temperature toughness. This steel material contains, in mass%, 0.15-0.45% of C, 0.05-1.00% of Si, 0.05-1.00% of Mn, 0.030% or less of P, 0.0050% or less of S, 0.005-0.100% of Al, 0.30-1.50% of Cr, 0.20-2.00% of Mo, 0.002-0.030% of Ti, 0.002-0.100% of Nb, 0.0005-0.0040% of B, 0.0100% or less of N, and 0.0040% or less of O, with the remainder comprising Fe and impurities, and has a yield strength of 862-1034 MPa. In the steel material, the number density of Al oxides having a major axis of at least 5.0 µm is less than 30 counts/200 mm2, and the number density of Si oxides having a major axis of at least 5.0 µm is 5 counts/200 mm2 or less.

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