Improvements relating to heat-resisting alloys and articles and parts made therefrom

715,140. Heat treatment of nickel alloys. MOND NICKEL CO., Ltd. Nov. 26, 1952 [Dec. 5, 1951], No. 28545/51. Classes 72 and 82 (1) The creep resistance of alloys containing 10-25 per cent. chromium, 1.8-4 per cent. titanium,. 0.5-4 per cent. aluminium, 00-25 per cent. cobalt, 0-10 per cent. iron, carbon in amount defined by the intersection of the ordinate corresponding to the cobalt content with the lines A and B on Fig. 1, and the balance nickel and unavoidable impurities, is increased by heating the alloy to 1150-1250‹C. for times corresponding to 2-12 hours at 1150‹C. and ¢ to 4 hours at 1250‹C., reducing the temperature to 1100‹C. maximum and holding for 2 hours in the range 800-1100‹C. and then holding for 1-24 hours at a temperature within the range 650-850‹C., but lower than the temperature of the second step. The second step may be an isothermal treatment or the alloy may be cooled slowly through the range of the second treatment and the third step may be isothermal, or slow cooling, or the alloy may be cooled to room temperature and reheated, Figs. 4, 5 and 6 (not shown), indicate the temperature range of the second step corresponding to the cobalt content for alloys containing 0.03-0.05 per cent. carbon, 0.06-0.09 per cent. carbon, and 0.1-0.15 per cent. carbon respectively. The alloy may also contain at least one of the following: silicon up to 1 per cent., copper up to 2 per cent., molybdenum and tungsten each up to 10 per cent., niobium, tantalum, or vanadium or any combination up to 5 per cent., zirconium up to 0.3 per cent., and boron up to 0.05 per cent.