Effect of laser power and welding speed on microstructure and mechanical properties of fibre laser-welded Inconel 617 thin sheet

Inconel alloy 617 was used in the present research because of its high strength and oxidation resistance in a wide range of temperatures. In this investigation, full-penetration welding of 1.5-mm-thin Inconel 617 plates in a butt configuration was carried out with a fibre laser welding machine of 400 W. The influence of different welding conditions, such as welding speed, welding power on the heat-affected zone morphology, metallurgy and mechanical properties has been discussed in detail in this study. Microstructures have been assessed by optical microscope and by field emission scanning electron microscope. On the other hand, mechanical behaviour has been analysed in terms of Vickers microhardness and compared with specimens of base materials under different welding conditions. Tensile test has been conducted on standard welded specimen and its tensile strength along with percentage elongation has been analysed and compared with base metal specimen. Surface topography at the fractured region of the specimen has also been studied. EDAX analysis has been done at different regions of the welded samples to study the chemical composition at various regions of the welded samples. During the investigation, XRD analysis was carried out at different positions (2θ°) to analyse the crystallographic structure and to get the maximum intensity of the compound matrix at different positions. During the microhardness test, hardness of the base metal was found to be lower in comparison with the fusion zone due to rapid cooling.