| 摘要 |
<p>A low alloy steel for a heat-resistant structure member being improved in high-temperature long-time creep ductility and temper softening resistance, characterized in that it comprises 0.03 to 0.10 mass% of C, 0. 30 mass% or less of Si, 1.0 mass% or less of Mn, more than 1.5 mass% and not more than 2.5 mass% of Cr, 0.01 to 1.0 mass% of Mo, 0.04 to 0.30 mass% of V, 0.001 to 0.10 mass% of Nb, 0.001 to 0.020 mass% of Ti, 0.0001 to 0.020 mass% of B, 0.001 to 0.01 mass% of Al, 0.0001 to 0.05 mass% of Nd and the balance comprising Fe and impurities, the impurities include 0. 020 mass% or less of P, 0.03 mass% or less of S, less than 0.0050 mass% of N and 0.0050 mass% or less of O(oxygen), and a value of BSO represented by the following formula (1) is 0.0001 to 0.010; BSO = B-(11/14)N-(11/32)S-(11/16)O----(1) where the symbol of an element in the formula (1) represents the content (mass %) of the element. The steel may further contain one or more of W, Cu, Ni, Co, Mg, Ca, La, Ce, Y, Sm and Pr.</p> |
