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Abstract:In the present study, Ti6Al4V titanium alloy plates were joined using a robotic fiber laser welding method. The laser welding process was carried out at two different welding speeds. Effects of different heat input conditions on the microstructure and mechanical properties of robotic fiber laser welded joints were investigated. Some grain coarsening was observed in the microstructure of weld metal in samples joined using high heat input, compared to those using low heat input, and volume rates of primary α structures increased in the weld metal. The microstructure of weld metal in samples joined using low heat input was made of basket-weave or acicular α' grains and primary β grains in grain boundaries. Tensile and yield strength of samples joined using low heat input were higher than for those joined using high heat input, but their ductility was lower.

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Duplex stainless steel is widely used in the oil, chemical industry and to a lesser extent in the medical industry, because of the high mechanical properties, corrosion resistance and good weldability. In this study, AISI 2205 (22Cr5Ni3Mo) duplex stainless steel samples were joined using the CO2 laser beam welding method. In order to determine the mechanical properties of the welded joints, tensile tests were applied and the hardness of the welded sample was measured on the cross-section. The microstructure characterization of welded samples was also carried out using optical microscopy, scanning electron microscopy and X-ray diffraction analysis. Although, the mechanical properties of welded samples were found acceptable, the final microstructure of the welded metal and the heat affected zone (HAZ) were significantly affected by the ferrite phase due to the low heat input that caused high cooling rates, respectively.