Temperature and Traverse Force Analysis During Underwater Friction Stir Welding

Abstract

Friction stir welding (FSW) is an auspicious clean welding method to join marine grade aluminum alloys (AAs). Underwater Friction Stir Welding (UFSW), can extend the marine application of the FSW due to its superior mechanical properties over its contemporary FSW. In FSW/UFSW the weld thermal cycles and tool forces exhibit a noteworthy effect on the weld properties. Force and temperature measurement during UFSW process play a pivotal role in understanding the process, prediction of tool life, microstructure and mechanical properties of the welded joints. As such an attempt has been made in this study to investigate the effect of welding speed (50–80 mm/min) on temperature distribution and traverse force during UFSW of AA 6082–T6. The results revealed that increase in welding speed caused high traverse force and low peak temperature. Furthermore, the increase in temperature was observed as the tool approaches the thermocouple near the weld center. After that, the temperature reduces due to a decrease in the thermal gradient. The maximum peak temperature of 137 ℃ was observed at the retreating side (RS) in heat affected zone (HAZ) at a low welding speed of 50 mm/min due to high heat input and slow cooling rate. Additionally, the maximum traverse force of 103 kgf was attained at a high welding speed of 80 mm/min due to high material flow stresses resulting from high strain rate and low temperature.