Peak Temperature Correlation and Temperature Distribution during Joining of AZ80A Mg Alloy by FSW – A Numerical and Experimental Investigation

Abstract

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.

Development of Thermo Mechanical Model for Prediction of Temperature Diffusion in Different FSW Tool Pin Geometries During Joining of AZ80A Mg Alloys

“…This unique transformation of grain structures is a direct evident to the fact that, the ideal peak temperature (ie., 348 0 C which is nearly 81 -82% of the melting temperature of AZ80A Workpiece) has been generated due to the employment of the FSW tool with optimal pin geometry (i.e., taper cylindrical pin geometry). This ideal peak temperature generation have led to superplasticity, which has contributed for plastically deformed material flow in an orderly manner, coupled together with dynamic recyrstallization of the grain structures [18,23,38,47]. Further detailed examination of these microstructures also helps us to understand that, generation of the peak temperature in ideal volumes plays a crucial part in deciding grain size & their refinement.…”

“…Several modelling based experimental investigations [40 -42] the course of formulation of the process model [43,44]. The generated computational domain for the joining of AZ80A mg alloy by FSW technique is shown in the Figure 4 and it can be visualized that, the surface of the workpiece is attached with two absolute dominion along the direction of xaxis.…”

“…In this experimental research, anticipated peak temperature Tmax was validated against experimentally measured temperature values and found to coincide with one another. Results of experimental runs carried out at the optimised process parameter conditions (i.e, tool rotational speed = 818 rpm; force applied on the FSW tool axially = 3.64 kN; rate of traversing of tool over workpiece = 1.48 mm/s) were taken as the inputs for generating line plots and contours [3,44]. The variations of temperature on the surface of the workpiece w.r.t the offset lines and bonding lines, when the tool approaches the workpiece centre part, for the various employed FSW tools with the different pin geometries are illustrated in the Figure 7 Figure 8 decribes in detail, the generated temperature contour graphs on the top surfce of the work piece and on the bonding surfaces for tools with different pin geometries.…”

“…Thus, it can be understood that, the technique of FSW joins materials in their solid state itself and due to this reason, it has various added merits like less input of energy, reduced volume of residual stresses, greater strength of weld etc when compared to that of the numerous fusion welding techniques [18,19]. But, inspite of the simple & user friendly principle of joining, there seems to exist various unexplored areas and research complications arising due to the anomalies occurring internal flow of plasticized materials due to the exhilarating action of the FSW tool pin geometry and by the generated heat arising from friction between shoulder and workpiece surface [20][21][22][23] Detailed illustration of the thermo mechanical anomaly occurring between the flat metal plates to be joined and the employed FSW tool pin will enable optimization of welding parameters, perfect design of FSW tool, extending the application of the FSW to various new dimensions [24 -26].…”

Development of Thermo Mechanical Model for Prediction of Temperature Diffusion In Different Fsw Tool Pin Geometries During Joining of Az80A Mg Alloys

“…Observational conclusions are also acquired for the above mentioned equational structures, emerging from those definite assessments. As it is evident that, the numerical dominion is well-proportioned along the line of weld, it is sufficient to consider only half of the flat plate of investigational workpiece, in the course of formulation of the process model [43,44]. The generated computational domain for the joining of AZ80A mg alloy by FSW technique is shown in the Figure 4 and it can be visualized that, the surface of the workpiece is attached with two absolute dominion along the direction of xaxis.…”