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Friction Stir Welding (FSW) was carried out on AA2219-T87 alloy plates with various process parameters. Multiparametric optimization was carried out using Taguchi-Grey Relational Analysis (T-GRA) to determine the most influencing factors on the responses like Ultimate Tensile Strength (UTS) and Yield strength (YS) of AA2219-T87 butt joints. In this work, defect-free welding parameters were selected from the wide range of trial and L18 Taguchi Mixed factorial design was fit to further optimize the parameters by T-GRA techniques. Parameters like tool rotational speed, welding speed and tool profile were varied, tool tilt angle and thrust force were kept constant. The macro and microstructures were examined to correlate with tensile, yield and hardness property to analyze the predominant factor that would improve joint efficiency. Finer grains were found in nuggets when compared to other zones and the grain size was found to decrease from top to bottom due to centrifugal action. Scanning Electron Microscopy (SEM) studies were carried out on fracture tensile specimen to determine the mode of fracture in the different regions. EDS elemental mapping was done in fracture region of the tensile specimen and it was encountered that crack initiation is along the copper-enriched region. Tensile strength was reported to be 73% of the parent metal and optimized parameter combination was observed for tool with taper threaded pin profile that enhances metal flow.

The contemporary trend of cost-saving is the primary motive while studying the relative motion between the material surfaces. Therefore, exceptional surface characteristics are the most desirable features for any material. The rapid emerging surface modification phenomena like Friction Stir Processing (FSP) have proved its potential in the surface engineering applications. In this study, Magnesium–Aluminum–Silicon (Mg–Al–Si)-based AS21A magnesium alloy was examined for the wear characterization in respect with the cast and Friction Stir Processed (FSPed) conditions. FSP, performed at an optimized set of parameters, was utilized to attain the surface modification in the investigated material. In the wear study, cast and FSPed conditions of AS21A specimens were examined on Pin-on-disc apparatus with typical load values ranging from 10–40N. The subsequent investigation involves characterization of worn surfaces through Scanning Electron Microscope (SEM) micrographs, and Energy Dispersive X-Ray Spectrometer (EDS) to understand the accountable wear mechanism. It was found that the FSPed AS21A samples exhibited noteworthy improvement in the wear characteristics at all assessment conditions. FSPed sample showed overall 17% enhancement in the specific wear rate. Also, with an increase in normal load, around 53–55% reduction was observed in the Coefficient of Friction (COF) value. It was established that the morphology of Mg₂Si precipitates had an active contribution in the wear behavior of cast and FSPed AS21A samples. The notable mechanisms found responsible for the wear of samples were adhesion, abrasion, oxidation, delamination and plastic deformation.

In this paper, experimental analysis was performed during micro-electrical discharge machining (micro-EDM) of titanium alloy Ti–6Al–4V (grade 5) using three types of tools viz. copper (Cu) tool, tungsten carbide (WC) tool, and synthetic graphite (Gr) grade three tool. The main process parameters were taken as (a) pulse on time ($T_{\mathrm{\text{on}}}$), (b) pulse off time ($T_{\mathrm{\text{off}}}$), (c) voltage (V), and (d) capacitance (C). The output responses were taken as the material removal rate (MRR) and tool wear rate (TWR). Taguchi method coupled with grey relational analysis (GRA) (L${}_{16}$ orthogonal array) technique was applied to optimize the input process parameters for both the responses. Scanning electron microscopy (SEM) analysis of the workpiece and tool was also performed to investigate the morphology of the machined surface and tool surface. Energy-dispersive spectroscopy (EDS) analysis was performed to investigate the elemental composition of the machined surface. The experimental finding reveals that tungsten carbide is the most suitable tool material for machining the chosen workpiece for obtaining optimal MRR and TWR. The optimum condition for the copper tool was found as 180V, 1000pf, 10$\mu$s ($T_{\mathrm{\text{on}}}$), and 10$\mu$s ($T_{\mathrm{\text{off}}}$). Meanwhile, the optimum parametric condition for tungsten carbide and graphite tools was found to be the same as 240V, 100pf, 20$\mu$s ($T_{\mathrm{\text{on}}}$), and 5$\mu$s ($T_{\mathrm{\text{off}}}$).