MICROSTRUCTURAL EFFECTS ON THE SLIDING WEAR-RESISTANCE OF A COBALT-BASED ALLOY

The influence of the microstructure on the dry sliding wear resistance of a hypo-eutectic Stellite 6 alloy was investigated under conditions leading to severe metallic wear of the hardfacing alloy. Conventional chill casting as well as laser surface cladding were used to produce a wide range of solidification microstructures. The hardness of the alloy was strongly dependent on the microstructure and in particular on the size of the dendrites. Under the sliding conditions investigated, severe delamination wear of the Stellite occurred. High coefficients of friction were measured and the structure in the subsurface was completely destroyed by the resulting stress cycles. During the stationary wear regime, no dependence of the wear rate on the as-solidified microstructure could therefore be determined. However, a strong influence on the wear resistance of alloying elements which affect the matrix properties was observed. Suggestions are made for the improvement of the wear resistance of such alloys under similar sliding conditions.