Characterization of stress rupture behavior of commercial-purity-Ti via burst testing

An understanding of the stress rupture behavior of Ti alloy tubing is of primary importance for structural applications in energy technology. The stress rupture properties were evaluated using burst testing of closed-end, thin-walled tubing at varied test temperatures and internal pressures. The rupture data are correlated using the Larson–Miller parameter. The uniform hoop strains were also measured along with rupture times from which the strain-rates were calculated. These results were fitted to Monkman–Grant relation with the aim of extrapolating to in-service stress levels. The activation energy for creep deformation was calculated from the Arrhenius equation, and the experimental data were analyzed using Dorn parameters. The analysis indicated a transition from a power-law controlled creep regime to power-law breakdown at high stresses. Transmission electron microscopy studies corroborated the transition in mechanism from power-law region to a power-law breakdown region.