Welding Superalloy Sheet for Superconducting Cable Jackets

Abstract

JBK-75, an iron-based supcralloy, has been selected for use as the cable jacket material for the Westinghouse magnet of the large coil project. Previous investigations of GTA welds of JBK-75 and its sister alloy, A-286, have shown that age-hardened weld metal has significantly lower yield and tensile strengths than comparable heat-treated base metal 1. In this investigation of A-286 weldments the nndermatching properties are shown to be the result of chemical segregation during weld pool solidification. This chemical segregation results in significant changes in the kinetics of preci pitation of the gamma prime (y') hardening phase.