Vg. Krishna et al., PROCESSING MAP FOR THE HOT-WORKING OF NEAR-ALPHA TITANIUM-ALLOY-685, Journal of materials processing technology, 71(3), 1997, pp. 377-383
Using a dynamic materials model, processing and instability maps have
been developed for near-alpha titanium alloy 685 in the temperature ra
nge 775-1025 degrees C and strain-rate range of 0.001-10 s(-1) to opti
mise its hot workability. The alloy's beta-transus temperature lies at
about 1020 degrees C. The material undergoes superplasticity with a p
eak efficiency of 80% at 975 degrees C and 0.001 s(-1), which are the
optimum parameters for alpha-beta working. The occurrence of superplas
ticity is attributed to two-phase microduplex structure, higher strain
-rate sensitivity, low flow stress and sigmoidal variation between log
flow stress and log strain rate. The material also exhibits how local
isation due to adiabatic shear-band formation up to its beta-transus t
emperature with strain rates greater than 0.02 s(-1) and thus cracking
along these regions. (C) 1997 Published by Elsevier Science S.A.