Effect of preexisting plastic deformation on the creep behavior of TP347 austenitic steel

We investigated the effect of preexisting plastic deformation with the strain of 30% on the creep behavior of TP347 austenitic steel at 650 °C with different applied stresses. The results showed that the creep rupture life of the prestrained sample increased more than that of the unstrained sample tested at 300, 250 and 200 MPa due to the strengthening of the mechanical twins induced by preexisting plastic deformation. Conversely, the prestrained samples were ruptured earlier than that of the unstrained sample tested when the lower creep stresses (150 and 125 MPa) were applied. The shorter creep rupture life of the prestrained sample was due to the reduced amount of time to a minimum creep rate and the shorter tertiary-stage creep time which can be related to the accelerated precipitation of sigma phase at the grain boundaries in the strained sample.