Wear mechanisms and hardness thresholds under repeated impact contact loading

Experiments were performed on 20 different types of materials to analyze the impact contact wear and to establish the wear mechanism map, The wear mechanism has been categorized into three prominent regions （delamination wear, quasi-nano wear and lamination-like wear） and is governed by two hardness thresholds （Hdq and Hql）. When the material hardness gcp〈Hdq, the delamination wear is the dominant wear mechanism; when Hcp〉Hql, the mechanism is lamination-like wear; however, whenHco is between Hdq and Hql, the mechanism is determined to be quasi-nano wear. Hdq is determined to be the threshold hardness between delamination wear and quasi-nano wear that reflects the cracks being produced in the subsurface layer, whereas, Hql is termed threshold hardness between quasi-nano wear and lamination-like wear with formation of nanostructure within the surface layer.