PURPOSE: To efficiently produce a material excellent in heat resistance by simplified means, by applying solution heat treatment to an Ni-Cr-Fe-type heat- resisting stock to which Nb is added and by subjecting the above to area- reducing cold working and then to aging treatment under specific conditions.
CONSTITUTION: A heat-resisting metal stock having a composition consisting of, by weight ratio, 45W60% Ni, 15W25% Cr, 3W7% (Nb+Ta), 2W5% Mo, <0.1% C, and the balance Fe with inevitable impurities or to which 0.1W1.0% Al and/or 0.1W1.5% Ti is further added is subjected to solution heat treatment at 900W1,250°C, which is then subjected to cold working accompanied by 10W80% reduction in area. Subsequently, aging treatment is applied at a temp. in range represented by an equation, t=2.5d+C [where (t) means aging temp., (d) means reduction in area attendant upon cold working before aging treatment, and C means a constant of 770W820), for 0.5W8hr. In this way, the heat-resisting metallic material such as spring material can be efficiently manufactured by means of the existing equipment.