Improved approaches for small punch test to estimate the yield and ultimate tensile strength of metallic materials

The small punch test (SPT) has been used extensively in nuclear industries to estimate mechanical properties changes of metals due to irradiation. This paper aims to propose more accurate approaches for SPT to estimate the yield and ultimate tensile strength of metals. The relationship between the SPT force and the yield and ultimate tensile strength of materials was studied by using finite element simulation data, and then three approaches were developed to determine tensile properties of materials by means of SPT. Force method and Slop method were developed to derive the ultimate tensile strength of metals from SPT curves, and Area method was proposed to determine the yield and ultimate tensile strength of metals. The accuracy of these approaches were verified by two candidate structural material for fusion reactors (CLF-1 steel and 9Cr-ODS steel) and other 10 structural materials. Area method gives more accurate evaluation on the yield strength of metals than the correlation method given in European standard on SPT. In addition, the developed approaches have advantages in estimating the tensile properties of low ductility metals.