Plating cracking deep drawn parts

I've got a small deep drawn product made from 3/4 hard, 304 Stainless. I need it to be black and the surface needs to be electrically conductive.

Our vendor suggested using a process they refer to as "black nickel strike". Unfortunately when the parts go through the blackening process they crack in the corners where the residual stresses are at their highest.

Can anyone suggest an alternative plating process which will give me a black, conductive surface with no cracks?

Thanks.