Research on grain refinement and wear behavior of micro-remelted Ta15 alloy surface by laser cleaning

Abstract

TA15 alloy has received widespread attention due to its excellent properties. The native oxide film limits its application. Laser cleaning can remove the native oxide film. However, research on the surface modification of materials by laser cleaning is rarely discussed. In this paper, the effects of different energy densities (E) on the improvement of surface morphology were studied. The wear morphology and microstructure were observed in situ. The difference between the wear mechanism between the remelted layer and the base material at different wear depths was analyzed. The results show the native morphological defects are transformed into a homogeneous crater after laser cleaning. With increasing energy, the crater morphology changes to a striation morphology. Tip growth of the supercooled melt and the cumulative of multiple processes results in morphology evolution. Compared to the base material, the coefficient of friction of the remelted layer decreased to 40%. Observing the microstructure in situ, the average grain area of the remelted layer decreased by about 40%. The large-angle grain boundary ratio increased. As E increases, the thickness of the remelted layer increases. Abrasion to 10 μm below the surface, the untreated sample showed furrow, scaly flaking, and pitting spalling. The laser-cleaned sample surface showed abrasions and plastic smearing. Abrasion to 50 μm below the surface, the surface of the remelted layer was fine abrasive particles. The surface of the untreated sample was larger abrasive particles and fatigue delamination.