The effect of testing environment on small punch creep

Small punch creep testing (SPCT) is currently experiencing a resurgence of interest as a small-scale testing technique (SSTT) for a wide range of uses, including testing in-service components and materials with limited availability. SPCT is particularly pertinent for the fusion community since it is difficult to irradiate large volumes of material due to the high damage levels required and relatively low number of available facilities. An important aspect of the SPCT development that still requires investigation is the effect of the testing environment, which has been shown to impact the creep properties of materials when using standard testing techniques. This paper investigates the effect of using an air or an argon environment on the SPCT behaviour of the leading European fusion reactor material Eurofer97 at 550°C. The test environment was found to impact on the small punch creep behaviour: testing in an argon environment significantly increased time to failure and deflection at failure by a factor of approximately 30 and 7%, respectively. The test environment also appeared to affect the behaviour of the test via oxidation of the punch head which should be an important consideration in future testing