①化学成分(百分数)满足
C≦0.030 Si≦0.40 Mn﹦2.5~3.0 P≦0.020 S≦0.015
Cr﹦24~26 Ni﹦19~21 Mo﹦2.50~3.00 N﹦0.20~0.30
②机械性能满足:
σb≧579MPa σ0.2≧294MPa δ5 ≧30%