Process for the production of a body of material stable at high temperatures from an iron-nickel superalloy of the type in 706

A process for the production of a body of material stable at high temperatures, the process comprising steps of:

• solution annealing and subsequent precipitation hardening of a hot work-hardened starting body composed of an iron-nickel superalloy having, in weight %, .ltoreq.0.02% C, .ltoreq.0.10% Si, .ltoreq.0.20% Mn, .ltoreq.0.002% S, .ltoreq.0.015% P, 15 to 18% Cr, 40 to 43% Ni, 0.1 to 0.3% Al, .ltoreq.0.30% Co, 1.5 to 1.8% Ti, .ltoreq.0.30% Cu, 2.8 to 3.2% Nb, balance Fe the starting body being cooled in a furnace at a cooling rate of between 1.degree. and 5.degree. C./min between the solution annealing and precipitation hardening steps, the precipitation hardening being preceded by an additional heat treatment stage in which the solution-annealed starting body is held at a temperature of between 800.degree. C. and 850.degree. C., the starting body being cooled at the rate of between 1.degree. and 5.degree. C. between the solution annealing and additional heat treatment steps and being cooled at the rate of between 1.degree. and 5.degree. C. between the additional heat treatment and precipitation hardening steps.