GB618560A - Heat resistant machinable alloy with high strength while hot - Google Patents

Abstract

A heat resistant machinable alloy, particularly suitable for apparatus, machines and furnaces working at high temperatures, having mainly a face centred cubic crystal structure and having high strength when hot, comprises 0.05-0.5 per cent of carbon, 0.20-2.5 per cent of silicon, 0.2-1.5 per cent of manganese, 7-80 per cent of nickel and/or cobalt, 11.5-30 per cent of chromium, up to 10 per cent each of one or more of tungsten, molybdenum, vanadium and antimony and the remainder iron, and comprising in addition up to 7.5 per cent in total of carbides of one or more of titanium, vanadium, zirconium, niobium, molybdenum hafnium tantalum, tungsten and thorium and finely divided particles of one or more strongly oxide-forming metals in total amount up to 12 per cent. The oxide-forming metals may be lithium, beryllium, magnesium, calcium, copper, strontium, zirconium, barium, cerium or thorium. The finely-divided particles of carbides and oxides may be added to a molten alloy or mixed in the alloy in a powder-metallurgical manner, or the basic elements composing the oxides and/or carbides may be added to a melt in stoichiometrical relation to each other. Thus a suitably proportioned amount of oxygen may be added to a melt followed by a metal having a strong affinity for oxygen. The oxygen content of the melt may be increased by using a melt rich in oxygen, by blowing in oxygen or by using the oxygen-containing atmosphere surrounding the melt at a higher pressure. The oxide-forming components may be added simultaneously with, before or after the carbide-forming metals.