1988 Volume 74 Issue 1 Pages 115-122
The powder of nickel-base suneralloy Mod. IN-100 was consolidated by hot isostatic pressing and recrystallized under the conditions of extrusion ratio of 72% at 1 373 K and subsequent annealing at 1 343 K×1h. The fine grain size of 1.5 μm in diameter was obtained.
The superplastic behaviour of alloy bars mentioned above was investigated in the temperature range of 1 2231 423 K and in the range of strain rates from 2.5 × 10-4 to 10-1 s-1.
The ln σ vs. ln ε curves were obtained. It was shown that the conditions obtaining the maximum strainrate sensitivity index, m changed from the constant strain rate of 10-2 s-1 at temperatures above 1 303 K to the constant flow stress of 150 MPa below 1 303 K. Therefore, it was possible to divide the ln σ vs. ln ε curves into six regions according to the deformation behaviour.
Furthermore, it was desirable to decrease the temperature continuously for the purpose of keeping the maximum m during superplastic deformation in tensile test. In fact, the total elongation exceeded extremely as compared with the isothermal test.
