Weldability of Alloy 718, 625 and Variants

The fusion zone weldability of a new alloy Inconel725 T”1. is presented and compared to Alloys 7 18,625 and Carpenter Custom Age 625 PlusTM*. Of these alloys, Inconel725 and Alloy 718 are most prone to solidification cracking during autogenous gas tungsten arc (GTA) welding as characterized by the Varestraint test. Each alloy typically forms a y/Laves terminal eutectic solidification product. In addition, other eutectics which form in some alloys include a y/MC and ‘y/M&, depending on composition. Formation of 6 (orthorhombic NigNb) adjacent to Laves and MC carbides in the interdendritic region was peculiar to Inconel 725 welds. Their possible relevance to solidification cracking tendency is discussed in terms of their volume fraction and contribution to solidification temperature range. t Inconel725 is a registered trademark of Into Alloys International. * Carpenter Custom Age 625 Plus is a registered trademark of Carpenter Technologies, Inc. Superalloys 718,625,706 and Various Derivatives Edited by E.A. Loria ‘he Minerals, Metals & Materials Society, 1994