et al.. Microstructure and residual stresses in Ti-6Al-4V alloy pulsed and unpulsed TIG welds. Journal of Materials Processing Technology, Elsevier, 2016, 231, pp.a b s t r a c tIncreasing the pulse frequency in pulsed Tungsten Inert Gas arc welding refines the prior-␤ grain size in the fusion zone of Ti-6Al-4V alloy compared to unpulsed process. The microhardness increases in the fusion zones (FZs) obtained with pulsed welding process with respect to their microstructural evolution. The increase of the pulse frequency contributes to the formation of a significant amount of residual ␤ phase in the FZ which is accompanied by a decrease of its microhardness. The tensile residual stresses (RSs) level in the pulsed process is lower than the one of the unpulsed one. The tensile RSs induced by both welding processes in the heat affected zone (HAZ) are found to decrease when increasing the pulse frequency. In the FZ, the transversal RSs are of compressive type for both processes whereas the longitudinal ones change from tensile to compressive type when increasing the pulse frequency.

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The microstructure and texture of an Al1050/AZ31/Al1050 laminated composite fabricated by accumulative roll bonding at 400°C up to 5 cycles are investigated using Electron BackScatter Diffraction, neutron diffraction, microhardness measurements and tensile tests. EBSD analysis has shown that ARB processing led to microstructural refinement with equiaxed grain microstructure in AZ31 layers and to the development of elongated grains parallel to the rolling direction in Al 1050 layers. No new phases formed at the bond interface after the first ARB cycle while Mg 17 Al 12 and Mg 2 Al 3 phases appeared after subsequent cycles. During the ARB processing, a typical strong basal (0002) texture is observed in AZ31 layers along with a weak rolling texture showed in Al 1050 layers with a dominant Rotated Cube {001}〈110〉 component. The microhardness of Al1050/AZ31/ Al1050 laminated composite increased with increasing ARB cycles and almost saturated after five ARB cycles. The yield strength and ultimate strength increased gradually between 1 and 3 ARB cycles due to the strain hardening and grain refinement. They decreased with further increasing of the ARB cycles because of crack and failure of the Mg x Al y intermetallic compounds which developed during 4th and 5th ARB cycles. The deformation behavior of the laminated composite becomes rather similar to the behavior of AZ31 alloy that underwent a dynamic recrystallization during processing.

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