Primary, secondary and anelastic creep of a high temperature near α-Ti alloy Ti6242Si

The creep behavior of the near alpha -Ti alloy Ti6242Si is investigated at 500 degreesC using constant stress tensile creep testing. Emphasis is put on primary and anelastic creep and their dependencies on processed microstructure and applied stress. The results of steady state creep are also reported. It is shown that the primary creep strain depends strongly on microstructure. Its dependence on stress is linear in the low stress regime, whereas a weak dependence is observed for high applied stresses. Unloading experiments lead to a time-dependent strain recovery that is also dependent on microstructure and prior stress. Unloading in the primary creep regime results in the recovery of almost all of the creep strain. However, a substantial strain recovery was also obtained upon unloading from steady state. It is shown that primary and anelastic creep strains are intimately related, and depend on microstructure and stress. The results are discussed with respect to existing dislocation creep models and the observed dislocation structures. (C) 2000 Elsevier Science Inc. All rights reserved.