Heat distribution in resistance upset butt welding

Resistance upset butt welding (RUW) has been employed for wheel rim manufacturing for many decades. Recently there has been a trend toward improved production methods and the use of high strength materials, accompanied by an increasing demand for knowledge about the RUW process. One of the phenomena observed during RUW is an uneven heat distribution and temperature profile during welding. This work examines potential causes for hot spot formation and compares experimental observations with predictions from a simple thermal model to illustrate aspects of importance for adequate process control and reduction of weld rejection rates.