Characterisation of low-temperature creep deformation and primary creep stage of TA2 using small punch creep test

The low-temperature creep deformation characteristics and primary creep behaviour of TA2 were analysed by the small punch creep (SPC) test in this paper. Uniaxial creep and SPC tests were conducted to estimate the temperature and load influences on the creep deformation. At room temperature and 373 K, an increase in the creep load and temperature caused a rapid increase in the creep deflection, exhibiting a greater primary creep deformation. Considering the non-linear deformation process, a modified membrane stretch model was introduced and a deformation analysis was performed. The creep deformation evolution process of a SPC test specimen was discussed. An apparent decline was observed in the equivalent creep stress and uniform thickness reduction was found. The material characteristics and stress reduction caused by the non-linear deformation were believed to be the cause of the primary creep behaviour of TA2. The results showed that SPC characteristic differs from that of the uniaxial creep test. To simplify the creep curve, a modified power relation between the creep deflection and time was established. Based on the constant strain rate test results, consideration of the strain rate sensitivity was applied to rationalise the low-temperature creep behaviour of TA2 in the uniaxial and multiaxial creep tests. Finally, a modified creep analysis model for the SPC test was proposed to predict the low-temperature creep deformation.