Small punch creep testing: Review on modelling and data interpretation

Abstract

In many situations where the characterisation of the mechanical behaviour of a specific material is required, source material for manufacture of conventional test specimens may be at a premium. Examples include the validation of new alloys for use in the power industry, the description of the heat affected zone (HAZ) of weldments 1 or performing a remnant life study on an in service component (such as steam pipe work used extensively in the power generation industry). The potential for a limit in sample material has necessitated the development of small specimen designs and associated test methods, particularly for the determination of the creep behaviour of a sample material. The small punch creep test (SPCT) has the potential to characterise the full uniaxial creep curve (as the specimen is taken to fracture). It is for this reason that the small punch creep test has attracted much interest from the research community. Owing to the complex deformation mechanism interactions experienced in the small punch creep test, interpretation of the results has received attention from many authors since its application was proposed by Parker et al. in the 1990s 2 (based on small punch plasticity test by Manahan et al. in the 1980s 3 ^– 5 ). In this review paper, several methods for the interpretation of small punch creep test (SPCT) data are reported and compared, together with examples of their application. Considerations for finite element (FE) modelling of small punch creep tests are highlighted and critiqued. Recommendations for potential areas of future research are also presented based on the authors’ investigation into published literature and research.