Influence of Surface Roughness on Rolling Contact Fatigue Behavior of Fe-Cr Alloy Coatings

Fe-Cr coating was prepared by plasma-spraying process. As-sprayed coatings were machined by grinding, lapping, or polishing processes as appropriate to get different surface roughnesses. Rolling contact fatigue (RCF) experiments were conducted using a ball-on-disk setup. RCF lifetime of the coating was calculated. The worn morphologies of the coating were observed. Results show that surface roughness obviously influences RCF behavior of the coating. The smooth coatings showed longer RCF lifetimes, and always failed by delamination. The rough coatings always failed by abrasion or spalling. The failure of smooth coatings was driven by the orthogonal shear stress and radial stress, whereas the failure of rough coatings was driven by the asperity contact.