In recent years, advances in creep data interpretation have been achieved either by modified Monkman-Grant relationships or through the more contemporary Wilshire equations, which offer the opportunity of predicting long term behaviour extrapolated from short term results. Long term lifing techniques prove extremely useful in creep dominated applications, such as in the power generation industry and in particular nuclear where large static loads are applied, equally a reduction in lead time for new alloy implementation within the industry is critical. The latter requirement brings about the utilisation of the small punch (SP) creep test, a widely recognised approach for obtaining useful mechanical property information from limited material volumes, as is typically the case with novel alloy development and for any in-situ mechanical testing that may be required. The ability to correlate SP creep results with uniaxial data is vital when considering the benefits of the technique. As such an equation has been developed, known as the kSP method, which has been proven to be an effective tool across several material systems. The current work now explores the application of the aforementioned empirical approaches to correlate small punch creep data obtained on a single crystal superalloy over a range of elevated temperatures. Finite element modelling through ABAQUS software based on the uniaxial creep data has also been implemented to characterise the SP deformation and help corroborate the experimental results.

Life extension of aging nuclear power plant components requires knowledge of the properties of the service-exposed materials. For instance, in long term service the tensile and creep properties might decline and the ductile-to-brittle transition temperature (DBTT) might shift towards higher temperatures. Monitoring of structural components in nuclear power plants receives much attention — in particular in the context of lifetime extension of current plants, where the amount of material available for destructive testing is limited. Much effort has therefore been invested in the development of miniature testing techniques that allow characterizing structural materials with small amounts of material. The small punch (SP) test is one of the most widely used of these techniques. It has been developed for nuclear applications but its use is spreading to other industries. Although the SP technique has been used for more than 30 years, there is currently no standard covering its most widely used applications. Within the auspices of ECISS TC 101 “Test methods for steel (other than chemical analysis)” WG 1 is currently developing an EN standard on the “Small Punch Test Method for Metallic Materials”. The standard will address small punch testing for the determination of tensile/fracture properties as well as small punch creep testing. This paper gives an overview of the state-of-the art of the SP tests and describes the scope of the standard under development.

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Small punch testing is now a widely recognised approach for obtaining useful mechanical property information of critical structural components, particularly in the nuclear industry. However, to date the utilisation of this method has been limited to isotropic materials such as aluminium alloys and steels. This paper will look to utilise the small punch (SP) test to assess the creep response of <001>-orientated CMSX-4® at temperatures above 950°C. An orthogonal rafting regime of the γ' structure is observed in the post-test microstructure due to the biaxial tension state typically produced in a SP test. Interpretation of the SP results to correlate with uniaxial creep data is carried out by employing the ksp approach in order to provide a platform for future material assessment. ®CMSX-4 is a registered trademark of Cannon-Muskegon Corporation