RESEARCH ON SURFACE STRENGTHENING INDUCED BY ULTRASONIC PUNCHING TO IMPROVE MECHANICAL PROPERTIES AND CORROSION RESISTANCE FOR SHAFT PARTS

Abstract

The shaft parts surface was treated by ultrasonic surface machining (USM) technology after surface induction hardening and tempering. In order to study the surface strengthening mechanism of ultrasonic punching on the surface of induction quenching and tempering, nano-intendation, X-ray diffraction, and scanning electron microscopy equipped with energy dispersive spectroscopy were utilized to evaluate the mechanical and corrosion properties of untreated and USM-treated surface. The results indicated that the surface treated by USM had an obviously gradient plastic deformation layer and the grain of lath martensite was refined by this deformation. The surface mircohardness of USM-treated sample had a gradient trend, and the surface highest hardness was increased. Surface residual stress of USM-treated specimen was higher than untreated surface. The surface of USM-treated specimen also exhibited a lower friction coefficient, and a smaller wear scar. In addition, the surface of USM-treated sample had better corrosion resistance than untreated surface.