GB1305608A - - Google Patents

Abstract

1305608 Metal powder mixture BIRMINGHAM SMALL ARMS CO Ltd 19 April 1971 [18 March 1970] 13096/70 Addition to 1009425 Heading C7A A mixture of powder from which, by powder metallurgy steel articles may be made consists of the elements Fe + impurities, balance, a constituent of the mixture comprising a powdered alloy, i.e. a prealloyed powder containing Ni, Mn, Mo and Fe. Preferably Ni 2 - 4À9, Mn 0À1 - 1, Mo 0À1 - 2. The pre-alloyed powder may contain the elements in any proportions such that on mixing with suitable additions, it produces the above composition. The additions may take the form of nickel or nickel carbonyl powder, ferro-manganese powder, molybdenum or ferro-molybdenum powder, soft iron powder. Up to 5% iron may be replaced by one or more of the following Al 1%, B 0À3%, Cr 5%, Cu 5%, Mg 1%, Nb and/or Ta 4%, P 0À3%, Si 1%, Ti 1%, W 4%, V 0À3%, Zr 0À6%, Se 0À6%, Pb 0À5%. A steel article is produced by mixing the powders, adding lubricants e.g. wax or stearates, compacting in a mould and sintering in a non-oxidizing atmosphere e. g. 75% H 2 , 25% N 2 or 70% H 2 , 25% CO, 5% N, at 100‹C.-1400‹C. for at least 30 minutes. Heat treatment may be applied to the sintered product and they may also be case hardened, electro-plated, phosphatized or coated with a diffusive chromium layer. A sintered article produced may be coined under pressure and further sintered at up to 1400‹ C under a suitable atmosphere.