1986 年 72 巻 9 号 p. 1351-1358
Superplastic isothermal forging process called Gatorizing has been developed for manufacturing of turbine discs of nickel-base superalloy IN-100.
A key point of this technology is a preform processing aimed at grain refinement for superplasticity but no details have been made public.
Therefore, powder-consolidated Mod. IN-100 samples made by a hot isostatic pressing were extruded at various reductions and temperatures.
The optimum conditions required to obtain the fine grained sound sample and the recrystallization behaviour during extrusion and subsequent annealing were investigated.
It was shown from results that (1) the reduction should exceed about 70% and (2) the temperature range should be 1 353-1 393 K, strictly speaking, 1 393 K was most desirable.
Furthermore, it was discussed whether a tensile strength and an elongation at 1 033 K of greater than 1 568 MPa and 20% which were aimed at by "the R & D Project of Basic Technology for Future Industries" sponsered by Agency of Industrial Science and Technology, MITI, were possible or not to be achieved by a optimum work processing, for a traditional alloy.