Uncertainties in and recommendations to small punch tensile and creep tests for ductile materials

•The complex deformation mechanisms of the small punch tensile and creep tests are clarified.•Specific features on the uncertainties of the test method in data interpretation are highlighted.•Critical comments on the applicability of the test method are given.•Recommendations and the opportunities for future developments are addressed. The objective of this paper is to clarify the complex nature which involves the interaction of several non-linear deformation mechanisms experienced in small punch tensile and small punch creep tests, and as a consequence, the associated difficulties in data interpretation. The paper starts with a highlight of some specific features experienced during small punch deformation, e.g., large deformation, high local plasticity, contact, the effect of initial plasticity, possible early cracking etc. and the consequences of them in data interpretation. Although several test standards have been available, uncertainties in data interpretation still exist and a universally accepted conversion method has not been available. On this basis, for the first time, critical comments on the uncertainties and applicability of the test methods in determining the tensile and creep properties and in high-temperature structural integrity assessment are addressed. Finally, recommendations on future developments are provided.