X2CrMoTi18-2 or 1.4521
C: 0.025% max Si: 1.00% max Mn: 1.00% max P: 0.040% max S: 0.015% max Cr: 17.0%-20.0% Mo: 1.80%-2.50% Ti: 4×(C+N)+0.15%-0.80% N: 0.030% max