Influence of microstructure on impact and wear behaviour of sintered Cr and Mo steel

The microstructure, mechanical properties, and dry rolling-sliding wear res istance of sintered Fe-Cr-Mo alloy and steel (0.4%C) were investigated as a function of microstructure. Graphite enhances sintering of chromium alloye d powder owing to the effect of free carbon on the reduction of chromium ox ide. A bainitic-martensitic microstructure is obtained after sintering with normal cooling on the carbon alloyed material. Impact properties are incre ased by the addition of graphite to the base powder. In the carbon alloyed material, they are higher in the as sintered condition than after heat trea tment because of the lower ductility of tempered martensite than that of lo wer bainite. Wear behaviour is strongly influenced by hardness. The increas e in hardness reduces delamination and favours the formation of a glazed su rface during rolling-sliding, which significantly reduces the wear rate.