a method of inertia friction welding a superalloy substrate , the method including : rotating and forcing a deposit material against the superalloy substrate ; plastically deforming at least one of the deposit material and the superalloy substrate to form a weld joining the deposit material to the superalloy substrate , thereby forming an assembly ; and heat - treating the assembly . heat - treating includes : a post - weld intermediate stress - relief treatment ; a solutionizing treatment ; and a precipitation hardening heat treatment .