1993 Volume 33 Issue 8 Pages 884-888
Ti-47mol%Al alloy powder produced by plasma rotating electrode process (PREP) was consolidated by HIPing at 1423 K and 176 MPa for 10.8 ks. Isothermal hot forging (IHF) with the small samples cut from the as-HIPed compact at 1223 K and an initial strain rate of 3.8×10–4 s–1 up to 78% reduction in height was carried out. This IHF process was considered to proceed by super plastic flow. A large pancake (approximately 25 mm thick with 140 mm diameter) without any crack was successfully obtained from the as-HIPed large compact (approximately 60 mmφ with 100 mm height) by the similar 78% IHF process. The results of the tensile strain-rate-change test and elongation to failure test of the specimens machined from the pancake indicated that this material exhibits fine grain superplasticity at elevated temperature higher than 1223 K. The maximum elongation to failure value of 398% was obtained at 1323 K and an initial strain rate of 2.8×10–4 s–1.
