Back (Edge zone)

1.7225 | 42CrMo4 nitrocarburized + oxidized

Numeric designation1.7225
Chemical designation42CrMo4
Statenitrocarburized + oxidized
Etching3 % Nital

The bright grain boundary precipitations in the diffusion zone are probably (chromium) nitrides, but could also be cementite. The oxidation after nitrocarburizing serves as corrosion protection; the approx. 1 µm thin oxide layer is only visible in places.