Parametric analysis on plastic deformation of materials during ultrasonic spot welding with different anvil geometries

Ultrasonic metal welding (USMW) has received noteworthy attention during recent years for its application to join lightweight materials. To improve the understanding of USMW process and to enhance the weld strength as well as quality, the present work is focused on the parametric study and its influence on the weld strength with various types of anvil tip geometries. It is observed that at higher weld time, an excessive amount of heat is produced at weld zone. Thus, a heavy plastic deformation occurs which is the major reason for over welding and lowering the weld strength. The temperature profiles for different types of anvils during the welding process are also examined at various weld conditions. The numbers of critical weld attributes are also identified to characterise the quality of weld formation over time. Microstructure study and microhardness measurement also have been employed to prove the severe plastic deformation in the interface layer as well as to establish a relationship between weld performance and physical weld attributes. As the weld time increases, the weld interface has been changed from planner to wavy morphology and the SEM micrographs proved the weld strength increments with the increase of waviness of the interface.