A quadratic equation has been developed based on experimental measurements to estimate the peak temperature in the friction stir welding (FSW) process during the joining of AZ80A Mg alloys. The numerical simulation of the FSW process was performed by employing COMSOL software to predict and calculate the distribution of temperature on the various regions of the parent metal and the welded joints. The predicted and finite element analysis (FEA) simulating the results of the distribution of peak temperatures were found to be consistent with the experimental values. In addition to this, a parametric experimental investigation was conducted to identify the most influential process parameter that plays a significant role in the peak temperature distribution during FSW of AZ80A Mg alloy. Linear contributions by the input process parameters of FSW, namely, traversing speed, rotating tool speed and axial force on the peak temperature were observed to be 32.82 %, 41.65 % and 21.76 %, respectively.

Heat generated during the friction stir welding (FSW) process is of complex nature and plays a vital role in influencing the quality of the fabricated joints. In this experimental research, an thermo mechanical process model was formulated to estimate the values of peak temperatures generated during the employment of FSW tools with four different pin geometries (namely cylindrical, taper cylindrical, square and triangle) for joining of AZ80A Mg alloy flat plates, to understand their significant role in influencing the size of the grains, their mechanical strength and in the quality of the joints. The peak temperature values of the formulated thermo mechanical process model are found to be consistent with that of the actual experimental results and exhibited relatively very small variation It was observed that the joints fabricated by taper cylindrical pin geometry was found to possess very fine sized grains, due to the generation of ideal peak temperature (ie., 348 0 C which is nearly 81-82% of the melting temperature of AZ80A Workpiece).

Peak temperature arising during the joining of metals by friction stir welding (FSW) needs to be investigated along with other process parameters of FSW to understand their inevitable impact on joint quality. This investigational and experimental analysis aims to determine the impact of pin geometry and its rotational speed by formulating thermic mechanical process-based models to anticipate peak temperature and to compare it with actual values. Three distinctive pin geometries rotated at three speeds were used while other parameters were unchanged. The fitness and suitability of the model were verified by comparing the anticipated values with the experimental values. Macrographic and micrographic observations revealed that flawless joints with improved mechanical properties were fabricated at a peak temperature of 616 K (80 % melting temperature) when a taper cylindrical pin with a rotational speed of 818 rpm was employed. In addition, SEM analysis of the fractured specimen confirmed that failure of the defect free weldment occurred in brittle mode, indicating that preferred fusion of grains and their constituents occurred during the joining process. Compared with other solid-state and unconventional welding techniques, such as electron beam welding, laser beam welding, and plasma arc welding, FSW is cheaper and more cost effective and does not require filler material and shielding medium (or gas), strict safety measures due to the absence of molten spatter and toxic fumes, skilled labor, long operation period, and cool down period, thereby boosting production rate and efficiency; moreover, FSW can be employed to fabricate joints in all positions, including horizontal, vertical, and overhead [12][13][14].

No abstract