THERMOMECHANICAL STRENGTHENING OF THE NICKEL-BASE SUPERALLOYS

摘要

1,268,844. Heat-treating nickel alloys. UNITED AIRCRAFT CORP. July 8, 1969 [July 19, 1968], No.34406/69. Heading C7A. Nickel-base super alloys are heat-treated to form a homogeneous distribution of precipitated SP1/SP phase, the latter having an interparticle spacing not exceeding 5 microns and forming a volume fraction of not less than 25%; they are then worked at a temperature not exceeding the solvus temperature of the SP1/SP phase or the gross recrystallization temperature, but not less than the minimum recovery temperature to effect a reduction in area of at least 15% without impairing the volume fraction or distribution of the SP1/SP. The alloy is then further heat-treated to stabilise it and provide additional precipitation strengthening. The first step may consist of solution treatment followed by ageing at a temperature between the SP1/SP solvus and the minimum recovery temperature. Working may be carried out near the minimum recovery temperature, when a random dislocation distribution is obtained, or near the solvus temperature, when the dislocations are aligned regularly along the polygonal sub-cell boundaries.