Liquation and post-weld heat treatment cracking in Rene 80 laser repair welds

摘要

An extensive experimental study on a nickel-based superalloy, Rene 80 usingautogenous laser welding has been undertaken to determine the effect of theprocess parameters and weld bead geometry on cracking in the as-welded and post-weld heat treated conditions. Little cracking was observed in the as-weldedcondition with low powers and beam diameters around 2.5mm. Welding speed hadlittle effect on the incidence of cracking in the as-welded condition.Investigation of the aspect ratio (penetration divided by width) indicated thatlittle cracking occurred in the as-welded condition when the aspect ratio wasapproximately 0.5. The same effect was observed with the post-weld heat treatedsamples. An analysis of the microstructures indicated that the cracking wascaused primarily by liquation in the as-welded condition and was exacerbated bypost-weld heat treatment cracking during the subsequent heat treatment. Finallythe study resolved some of the contradictory findings in the literature on theeffect of process parameters on the incidence of cracking in the as-welded andpost-weld heat treated conditions.