| 摘要 |
PROBLEM TO BE SOLVED: To provide an austenitic heat resisting steel containing combinedly added Cu, Nb, and N, which is excellent in hot workability and causes no problem when subjected to a tube making process by hot rolling using a cross roll piercer. SOLUTION: The steel has a composition which contains, by weight, 0.03 to 0.15% C, <=1.0% Si, 0.10 to 2.0% Mn, <=0.030% P, <=0.0010% S, 15.0 to 25.0% Cr, 6.0 to 25.0% Ni, 2.0 to 6.0% Cu, 0.10 to 0.80% Nb, 0.050 to 0.25% Ni, 0.0005 to 0.010% B, 0.001 to 0.10% Al, <=0.0050% O, and 0.0010 to 0.010% Ca or/and 0.0010 to 0.010% Mg and in which the relationship among Ca, Mg, O, and S satisfies the inequality: [3.0<= (Ca+Mg)-0.1×O}/S<=15.0] (where each symbol of element in the inequality represents the content (wt.%) of the element itself contained in the steel).
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