Effect of double-side welding on the microstructural characteristics and mechanical performance of dissimilar AA6061-AA5052 aluminium alloys

In this study, cold metal transfer (CMT) based double-side welding process was employed to weld AA5052-H32 and AA6061-T6 plates having a thickness of 6 mm. The microstructure and mechanical integrity of the weldment was examined systematically. Symmetric and defect free joint with full penetration was achieved. The multiple heating and cooling cycles during CMT welding did not affect the weldment while the microstructure comprised of columnar and equiaxed dendrites and the heat affected zone (HAZ) width was < 50 µm at all interfaces. Precipitates such as Al3Mg2, Mg2Si, and α-Al(FeMn)Si were observed in the fusion zone. Intergranular Al-Si eutectic structure along with few microliquefaction cracks were noticed in the α-Al matrix. The maximum tensile properties for double-side welded joint were 214 MPa and 12.30 % with a joint efficiency of 70.68 %. Tensile specimens underwent ductile fracture in the weaker AA5052-H32 side with confined plastic deformation

Improvement of Surface Finish and Reduction of Tool Wear during Hard Turning of AISI D3 using Magnetorheological Damper

35-40Smart materials are the materials that have one or more properties that can be significantly changed in a controlled fashion by external stimuli such as stress, temperature, moisture, pH, electric or magnetic fields.Magneto-rheological fluids are smart fluids, which can change their viscosity when a magnetic field is applied. That is, the liquid material will change to a semi-solid under the influence of the magnetic field. Hard turning has gained popularity in machining industries as an alternative to conventional cycle of turning, heat treatment and then finishing for assembly of high wear resistant parts. Vibration developed during the hard turning is the major reason for poor surface finish of the parts produced by this process. The present investigation aims at developing the magneto rheological damper for suppressing the tool vibration and promoting better surface finish. Experiments were conducted on AISI D3 steel of HRC 60 turned with multicoated hard metal inserts with sculptured rake face geometry .This study also presentsmultivariate loss function for multi criteria optimization of surface finish and tool wear. Experimental results revealed that use of MR damper reduced the surface roughness by three times when compared with that of not using MR damper. Results also revealed that the optimum parameters to improve the surface finish and reduce the tool wear simultaneously are cutting speed 120 m/min and feed rate 0.08 mm/rev