Abstract: The surfaces of 316 L stainless steel,a new material in auto-industry, were modified with the WC-Ni coatings deposited by laser cladding and in-situ irradiated by ultrasonic wave in rapid solidification of the laser-melted spots.The influence of the ultrasonic irradiation on the microstructures and tribological behavior of the WC-Ni coatings was investigated with scanning electron microscopy and conventional mechanical probes.The preliminary results show that the ultrasonic irradiation significantly improved the surface modification.For example,the ultrasonic irradiation resulted in the formation of a large number of finer equiaxed and some smaller dendrites grains,increased the micro-hardness,reduced the friction coefficient from 0.59 to 0.42,and considerably improved the wear resistance.Possible mechanisms responsible for the improved tribological properties and grain-size reduction of the laser cladded WC-Ni coatings were also tentatively discussed in a thought provoking way.