GB647701A - Improvements in and relating to nickel chromium steels - Google Patents

Abstract

Austenitic steels have the following composition: C 0.08-1.0 per cent; Si 0.1-2.0 per cent; Mn 0.1-5.0 per cent; Ni 5-30 per cent; Cr 5-21 per cent; W and/or Mo 1.5-15 per cent; Nb with or without Ta, the minimum quantity of Nb being 0.05 per cent when Ta is present, with the optional presence of V for part of the Nb or Nb and Ta, the quantity of Nb or Nb and Ta not falling below 1.0 per cent when V is present, the total quantity of these elements being 0.25-15 per cent; Co 3-30 per cent; N 0.0.3 per cent; Cu 0-6 per cent; Fe, not less than 33 per cent, constituting with unavoidable impurities the balance. The sum of the Ni and Cr proportions is not less than 24 per cent. The Nb with or without one or both of Ta and V may be added in a vacuum furnace or in conditions in which a non-oxidizing atmosphere is employed. The alloy may be used for machine parts and other articles which are subjected to high stress and high temperatures particularly discs, rotors, vanes or blades of gas turbines or for valves of high duty internal combustion engines. The Provisional Specification describes also alloys within the ranges set forth below: C 0.08-1.0 per cent; Si 0.1-2.0 per cent; Mn 0.1-2.0 per cent; Ni 5.0-3.0 per cent; Cr 5.0-30.0 per cent; W 0.05-10.0 per cent; Nb 0.05-15.0 per cent; Mo 0-15.0; Co 0-30.0 per cent; N 0-0.5 per cent in which alloy Nb may be partly replaced by Ta and/or V.