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

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.

Generation of regression models and multi-response optimization of friction stir welding technique parameters during the fabrication of AZ80A Mg alloy joints

Conventional methodologies employed for the selection of weld process parameters for fabricating sound quality weldments have been found to consume more time and are often unreliable. Therefore, in this paper, an analysis was made to develop a quadratic regression model and empirical relationships by employing response surface methodology between various input parameters of the friction stir welding (FSW) technique including rotational speed of tool, axial force, and traversing speed of tool and five responses of output including percentage of elongation, yield strength, tensile strength, grain size, and microhardness. The discrepancies between the anticipated values and the genuine experimental outcomes are within ±1%, which reveals that the established mathematical quadratic regression model was a good fit to the actual experimental results. The experimental analysis also determined the elite combination of input parameters of the FSW technique for the output parameters.

Influence of tool rotational speed on microstructural characteristics of dissimilar Mg alloys during friction stir welding

Dissimilar friction stir welding of the AZ80A Mg alloy as the advancing side and the AZ91C Mg alloy as the retreating side was carried out at a constant feed rate of 75 mm/min using a taper cylindrical pin profiled tool at different tool rotational speeds. Defect free welds were produced in the 700–900 rpm rotational speed range. During friction stir welding, extrusion of metal took place in the advancing side and this extruded material was dynamically recrystallized and redeposited on the retreating side. This experimental investigation revealed that friction stir welding leads to the formation of comparatively finer sized grains on the retreating side of the thermo-mechanically affected zone compared to grains in the thermo-mechanically affected zone on the advancing side. Moreover, the heat affected zone of AZ80A possessed fine sized grains compared to the heat affected zone of AZ91C. Additionally, increasing tool rotational speed influenced the tensile strength of the fabricated joints.

Influence of The Arrangement of Materials and Microstructural Analysis During FSW of AZ80A & AZ91C Mg Alloys

The main objective of this paper is to produce defect free weldments with improved properties during friction stir welding of dissimilar Mg alloys. The influence of the anisotropic arrangement of materials when AZ80A Mg alloy is taken as advancing side and AZ91C Mg alloy as retreating side and vice versa with respect to their mechanical properties and microstructural characteristics were investigated. The effects of various FSW parameters on the quality of these joints were also analyzed and best optimized FSW parameters were suggested. Defect free sound joints with excellent mechanical properties were produced when AZ80A Mg alloy was positioned at retreating side. At the same time, it seems a little bit difficult to obtain good quality joints with the contrary arrangement of materials. These investigations revealed that materials having inferior plastic deformability must be kept at the advancing side to obtain sound joints during FSW of dissimilar alloys of Magnesium.

Investigation on Evolution of Microstructures and Characterization During FSW of Az80a Mg Alloy

Experimental investigation was conducted to find out microstructural characteristic changes arising in the weldments AZ80A Mg alloys obtained using the friction stir welding. Tools with three different pin profile geometries were employed during this investigation at constant tool rotational speed and feed rate. Tensile tests are performed and the tensile fracture surfaces are examined using the Scanning Electron Microscope (SEM) and the obtained SEM images are used for microstructural investigations. From the experimental results, it was observed that the geometry of the tool pin plays a significant role in producing essential stirring action there by regulating the flow of the plasticized material and leading to the formation of small sized grains having equally distributed fine strengthening precipitates. These structured grains have a direct reflecting impact in increasing the hardness and mechanical properties of the fabricated joints at the nugget zone of the friction stir welded AZ80A Mg alloy joints.