Primary, secondary and anelastic creep of a high temperature near alpha-Tialloy 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 o n primary and anelastic creep and their dependencies on processed microstru cture and applied stress. The results of steady state creep are also report ed. It is shown that the primary creep strain depends strongly on microstru cture. Its dependence on stress is linear in the low stress regime, whereas a weak dependence is observed for high applied stresses. Unloading experim ents lead to a time-dependent strain recovery that is also dependent on mic rostructure 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 s hown that primary and anelastic creep strains are intimately related, and d epend on microstructure and stress. The results are discussed with respect to existing dislocation creep models and the observed dislocation structure s. (C) 2000 Elsevier Science Inc. All rights reserved.