Abstract: A heat treatment process for material bodies made of a high-temperature-resistant iron-nickel superalloy of the type IN 706 comprises the following steps: solution annealing at approximately 965 to 995.degree. C. for 5 to 20 hours, stabilization annealing at approximately 775 to 835.degree. C. for 5 to 100 hours, and precipitation hardening at 715 to 745.degree. C. for 10 to 50 hours and at 595 to 625.degree. C. for 10 to 50 hours. A heat-treated material body of this kind, made of a high-temperature-resistant iron-nickel superalloy of the type IN 706 exhibits a crack growth rate of less than 0.05 mm/h and/or exhibits a minimum elongation of 2.5% without cracks at a constant strain rate of 0.05%/h and a temperature of 600.degree. C.

Abstract: In a method for welding age-hardenable nickel-base alloys, a workpiece (5) made from an age-hardenable nickel-base alloy (1, 2) is welded with filler material of the same composition as the base material. The weld metal (3) which is formed in so doing is covered by a sealed covering layer (4) comprising a ductile material and the workpiece (5) is subjected to hot isostatic pressing (HIP).