•
CrCN coatings with diverse carbon concentrations were deposited on 316 L disks.
•
All coated 316 L performed better corrosion resistance than uncoated 316 L in SBF.
•
CrCN coating (15.4 at.% C) with N–C bond alone was a favorable candidate.
•
Protective effect of CrCN (52.6 and 75.0 at.% C) was degraded by unstable NC bond.