Experimental investigation on the improvement of the properties of the AZ80A Mg alloy joints using friction stir welding process

Abstract

An experimental investigation was conducted with the basic objective of demonstrating the feasibility of joining the AZ80A Mg alloys using the technique of friction stir welding (FSW). Good quality joints free from defects were obtained for 5mm thickness AZ80A Mg alloy flat plates at a speed of rotation of 750 rpm with a traversing speed of 1.5 mm/min, by employing a FSW tool fabricated out of M35 grade High Speed Steel(HSS). It was experimetally observed that, the nugget zone (NZ) of the defect free weldments were found with fine sized, equally spaced & uniformly distributed grains when compared with that of the parent metal. Apart from this, the heat affected zone (HAZ) lying beside the NZ was found to possess larger sized near equaxied grains due to the effect of annealing. The weld zones were found to possess regions of slight softening nature when compared to that of the parent metal, arising from the dislocation of the lower densities. Moreover, the tensile strength of the defect free weldments was found to be around 78% of the parent metal, which seems to better than that of the strengths obtained using conventional joining techniques.

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.…”

Investigation of the Effect of Heat Transfer during Friction Stir Welding (FSW) of AZ80A Mg Alloy Plates using a Pin Tool by Conducting Finite Elements Analysis

“…Magnesium alloys, and low-density magnesium alloys in particular (such as AZ80A), are used in a wide variety of applications within the automotive and aerospace industries as a result of their high strength (specific strength), rigidity, attractive damping capacity, and consistent dimensions both prior to and after machining [1]. This is due to the fact that low-density magnesium alloys have a higher specific strength than their higher density counterparts [2]. The extensive use of magnesium alloys can be attributed, in large part, to the fact that they have desirable damping properties in addition to their high specific strength and stiffness.…”

Simulation of heat transfer and analysis of impact of tool pin geometry and tool speed during friction stir welding of AZ80A Mg alloy plates

“…Identification of a suitable joining technique for Mg alloys is challenging because they are prone to premature cracks, porosity, and severe stresses (residual), making them unsuitable for fusion joining. Therefore, the welded quality of Mg alloy joints must be investigated to broaden the application of these alloys [6][7][8][9].…”