Effect of Weld Speed on Joint Quality of Nd: YAG Laser Welded Inconel 718 Alloy Weldments

Inconel 718, a nickel based superalloy is used in all kinds of applications where outstanding strength and corrosion resistance are essential. The Inconel 718 alloys joints from sheets of 1mm thickness are fabricated using a 4 kW Nd: YAG laser welding equipment. The influence of welding speed on the weld bead ripples, weld morphology, defects and the mechanical properties are investigated. Microstructure of the weld fusion zone, Heat Affected Zone (HAZ) and the weld ripple structure were analyzed using optical microscope and the scanning electron microscope. The weldments obtained were with nominal cracks, porosity and shape imperfections that signifying Nd: YAG laser welding as an effective method for fabricating joints of Inconel 718 of thickness 1mm. The weld fusion zone consists of fine dendritic structure and HAZ is found with columnar grain structure. The welded joints found with a higher joint strength but with a reduced ductility owing to the formation of detrimental laves phase.