Comparison between ultrasonic vibration-assisted upsetting and conventional upsetting

Abstract

Ultrasonic vibration has been increasingly applied to metal forming processes due to its beneficial effects on the reduction of the forming force, flow stress, and friction coefficient and on the increase of the forming limit of the sheet metal. In this work, the effect of the ultrasonic vibration on the upsetting has been studied experimentally and numerically. The microstructure of the specimens processed with ultrasonic vibration-assisted upsetting (UAU) and conventional upsetting was characterized. Differences in the forming characteristics between these two methods, in terms of metal flow and forming force, were analyzed. The results of this study indicate that the use of high-intensity ultrasonic vibration can induce severe plastic deformation and improve the grain refinement efficiency. The grains of the specimens processed by the UAU process were refined to 100 to 300 nm. A deformation mechanism of the UAU process was proposed. The grain refinement mechanism was used to explain the reason why ultrasonic vibration can be used to improve the grain refinement efficiency of the upsetting process. © The Minerals, Metals & Materials Society and ASM International 2013.