GB424124A - Improvements in processes for thermally hardening steels and alloy steels - Google Patents

Abstract

424,124. Hardening steel. ELLIS, R. E., 70, Chancery Lane, London.-(United States Steel Corporation; 71, Broadway, New York, U.S.A.) May 15, 1933, No. 14092. [Classes 72 and 82 (i)] A process for hardening steel comprises quenching from above the critical temperature to below the temperature of rapid pearlite formation but above that at which rapid conversion of austenite to martensite is obtained, maintaining the quenched steel within that range, which may be 300-1000‹ C., for at least sufficient time to obtain conversion of the austenite to crystal structures other than pure martensite, and then cooling to atmospheric temperature. The heating may be effected in an inert or reducing atmosphere. The steels treated may contain up to about 2 per cent of carbon, and various amounts of nickel, manganese, silicon, chromium, tungsten, molybdenum, vanadium and titanium, the following being specifically referred to :- 1À13 per cent of manganese and 0À64 per cent of carbon; 3À88 per cent of nickel and 0À55 per cent of carbon ; 11À5 per cent of chromium and 0À35 per cent of carbon; 0À36 per cent of manganese, 0À78 per cent of carbon and 0À16 per cent of silicon. The articles treated may be wire, strip, rails, cutlery, tools, bearings, &c. Apparatus for treating wire, strip, &c., 5 comprises a heating furnace and 1 hardening bath 2, containing preferably lead or a lead alloy, both thermostatically controlled and preferably electrically heated, with means 13 to submerge the wire, with or without the interposition of other cooling means between the furnace 1 and bath 2. Reference has been directed by the Comptroller to Specification 10738/00, [Class 72].