[MadKaw]

It's black (Parkurized?) on Tenifer.
Tenifer is a nitrocarburizing process that leaves the surface very hard, and corrosion resistant.
Taurus International Manufacturing Inc
Ferritic nitrocarburizing - Wikipedia, the free encyclopedia

 

[MadKaw]

BTW: Two years after much of the black wore off, there is not a single sign of corrosion or wear on underlying gray Tenifer surface