WELDABILITY OF A NEWLY DEVELOPED 718 PLUS AND INCONEL 718 SUPERALLOY

摘要

Weldability of a newly developed Ni base superalloy, Allvac 718 Plus (718 Plus), and the baseline superalloy Inconel 718 was investigated by hot ductility measurements by Gleeble Thermo mechanical simulator, and by evaluating microfissuring in bead on plate electron beam welds. Microstructures of the pre-welded and as welded alloys were characterized by optical and analytical electron microscopy. Grain boundary liquation and constitutional liquation of Nb rich MC type carbides were observed in the HAZ microstructure. Weld cracking measurements and the hot ductility of the alloys suggested that weldability of the baseline superalloy Inconel 718 was marginally better than that of the newly developed 718 Plus alloy. The causes and mechanism(s) of liquation and the differences in the weldability of the two alloys were discussed.