Cyclic deformation behaviour of commercially pure titanium at cryogenic temperature

Push-pull law-cycle fatigue tests were carried out on annealed and hot-roll ed commercially pure titanium under total strain control at 77 K. Very obvi ous cyclic-hardening behaviour was observed at the beginning of fatigue for the strain amplitudes employed. A large number of twins with various appea rances was observed in the microstructure of fatigued specimens of annealed and hot-rolled titanium. Three twinning systems, (11 (2) over bar(1) over bar), (1 (1) over bar 02) and (1 (2) over bar 12) types, are operative in t he cyclic deformation of titanium. Twinning is considered to be the main de formation mode of pure titanium fatigued at 77 K and to be the main reason for the cyclic hardening of pure titanium at low temperature. (C) 2001 Else vier Science Ltd. All rights reserved.