Thermal Dissipation Effect on Temperature-controlled Friction Stir Welding

Abstract

During Friction Stir Welding (FSW) of complex geometries, the thermal dissipation, induced by geometric features or the surrounding environment, may strongly affect the final weld quality. In order to guarantee a consistent weld quality for different conditions, in-process welding parameter adaptation is needed. This paper studies the effect of thermal dissipation, induced by the backing bar thermal conductivity, on the weld temperature and the temperature controller response to it. A new temperature sensor solution, the Tool-Workpiece Thermocouple (TWT) method, was applied to acquire online temperature measurements during welding. An FSW-robot equipped with temperature control, achieved by rotation speed adaptation, was used. AA7075-T6 lap joints were performed with and without temperature control. The cooling rate during welding was register plus macrographs and tensile tests were assessed. The controller demonstrated a fast response promoting the heat input necessary to maintain the set welding temperature. The results demonstrated that temperature control using the TWT method is suitable to achieve higher joint performance and provides a fast setup of optimal parameters for different environments.

Experimental analysis on friction stir welding using flat-faced pins in AA2024-T3 plate

“…This indicates that the maximum heat supply varies with respect to the process conditions and maximum achievable process peak temperature depends on the amount of heat supply. It also can be noticed that in every tool pin geometry some trails are carried out with higher heat supply (Trails 3,4,7,8,11,12,14 & 16). In these trails the increase in temperature is steady.…”

Temperature-controlled friction stir welds of age-hardenable aluminum alloys characterized by positron annihilation lifetime spectroscopy

“…Temperature-controlled friction stir welding has been investigated from two principal approaches: power/torque-based control and spindlespeed-based control. [8][9][10][11][12][13][14] Most of these temperaturecontrol methods utilize temperature and material flow simulations or proportional-integral derivative (PID) gains to control temperature throughout a weld. 15,16 Either method, however, is quite capable of holding the maximum weld temperature to within 62°C.…”