Critical evaluation of the small punch test as a screening procedure for mechanical properties

Within a collective exercise, a systematic and statistically based analysis of the repeatability and device dependence of small punch test results was performed. An unirradiated ferritic-martensitic steel T91 was selected for this. The test results allowed an evaluation of accuracy and reliability of material properties extracted from load–displacement-based and energy-based parameters. In a second step, neutron irradiated T91 with doses of 2.3 and 4 dpa was investigated in the temperature range −165 °C to 300 °C. The effects of test temperature and irradiation on the load–displacement curves and on the derived parameters were analysed. It was found that the small punch test is well suited for estimation of neutron embrittlement in cases of small amounts of available material or high activity. The preferred procedure for that purpose was specified.