Some investigative studies on dissimilar metals by friction stir welding

Abstract

The aim of the current work is to develop weldments and to investigate the microstructure and mechanical properties of the aluminium alloy 6061-T6 and magnesium alloy AE42 plates (120x100x3 mm) which are welded through FSW. H13 conical thread tool pin was selected to prepare the welded joints. Two plates that were co-ordinated vertically according to the welding directions were well joined. In this study, two parameters such as weld speed at 60,150 mm / min and tool rotation speed at 800, 1200 RPM are taken into account as defect free. By changing these parameters similar and dissimilar alloys are welded together. Tensile specimens (according to ASTM standards) were developed to estimate mechanical properties including tensile strength, % elongation, yield s trength and joint efficiency. It was found that an increase in the tool rotational speed or welding speed of the tool led to an increase in the tensile strength, which reached a maximum value and then decreased. (LOM) Light optical Microscopy research was accustomed examine and study the weld zone properties. Dynamic recrystallization was discovered within the weld region in addition as within the thermo-mechanical heat-affected zone (TMAZ). There’s a transparent reduction within the quantity of precipitate through the TMAZ and from the BM (Base Material) into the weld zone. Observed precipitates from similar and dissimilar welded joints -Mg2Si, Al2O3, SiC, Mg17Al12, Mg2Al3, Al11Ce3 and Al2Ce. Welds are without porosity. XRD with the EDS characterization was executed in the NZ (Nugget Zone) demonstrated the existence of SEM intermetallic phases and their weight in percent. Rapid phase structures of welded joints were detected using X-ray diffraction (XRD), however, the SEM fractograph indicated a flexible ductile fracture mechanism. Vickers micro-hardness test was performed on the thickness of the plate within the weld space to review and perceive the variation of hardness with thickness. An interrelationship between size of precipitate and micro hardness was ascertained. The corrosion behaviour of the base alloy and welded joints was measured in 3.5% NaCl solution using the salt spray test and by investigating the corrosion parameters (corrosion rate, exposure time and weight reduction). Corroded products were analysed and classified using optical microscopy and SEM. The corrosion rate decreases with increasing exposure time, but remains uniform as the corrosion time increases. Finally, a three-dimensional finite element phases was developed for temperature evolution in the friction-stir welded joint plunge depth, dwell, moving phases, and the heat conduction effect is arbitrary in the LAGARAGIAN-EULERIAN formulation in the ABAQUS / EXPLICIT, Johnson-Cook (JC) elastic-plastic model Will be used. The JC model defines the strength of the material as a function of three parameters, i.e. the strength of the material depends on the strain hardening effects, strain rate effects and temperature and verifies the s imulated results with the experimental results.