Material transfer phenomena and failure mechanisms of a nanostructured Cr–Al–N coating in laboratory wear tests and an industrial punch tool application

In this research, CrAlN and TiN coatings were deposited on AISI M2 tool steel substrate test coupons and on industrial punch tools by electron beam plasma-assisted physical vapour deposition (EB-PAPVD). The microstructure and morphology of the coatings were investigated by XRD, XPS, TEM, and SEM with EDX. Pin-on-disc tribotests were conducted on the coatings against AISI 52100 steel counterface material in order to investigate their wear performance, with particular emphasis on the material transfer phenomena during the sliding tests. After industrial trials on piercing high strength steels, the worn uncoated as well as CrAlN- and TiN-coated punches were also studied. The results showed that the nanostructured CrAlN coating exhibited less material transfer and thus better adhesive wear protection than the TiN coating under both laboratory pin-on-disc tribotests and industrial trial conditions. It was also found that the coating morphologies replicated the surface finish of the punch substrates, and that local coating spallation appeared to be initiated at machining grooves on the punches, which were detrimental to the coating lifetime.