X1CrNiMoCuN25-25-5 or 1.4537
C: 0.020% max Si: 0.70% max Mn: 2.00% max P: 0.030% max S: 0.010% max Cr: 24.0%-26.0% Mo: 4.70%-5.70% Ni: 24.0%-27.0% Cu: 1.00%-2.00% N: 0.17%-0.25%