| 摘要 |
PURPOSE: To produce an austenitic steel excellent in stress corrosion cracking resistance, strength, and resistance to irradiation embrittlement by specifying respective contents of C, Si, Mn, Ni, Cr, and impurities and precipitating carbides in a single-crystal austenitic phase. CONSTITUTION: An austenitic steel, which has a composition containing, by weight, 0.03-0.20% C, <=1% Si, <=2.0% Mn, 9-21% Ni, 14-20% Cr, and <=0.5% inevitable impurities and further containing, if necessary, 0.5-2.0% Pd and further 1-4.0% Mo and further one or more elements among Ti, Zr, V, Nb, and Ta, defined by 1<(Ti+Zr+V+Nb+Ta)/(C+0.043)<2, is used, This austenitic steel is subjected to unidirectional solidification, by which single-crystal austenitic phase and <=10vol.% ferritic phase are formed. Then, this steel is subjected to solution heat treatment in two stages at 1050-1150 deg.C and at 1200-1300 deg.C. Subsequently, aging treatment is performed at 600-900 deg.C, by which carbides of <=0.5μm diameter and <=1μm length are finely precipitated at 5-20% area ratio in the base phase. |
