Creep property measurements of welded joint of reduced-activation ferritic steel by the small-punch creep test

The small-punch (SP) test and the SP creep test were carried out by using a further miniaturized plate-type specimen (3 mm diameter × 0.25 mm thick). Those tests were applied to the electron-beam welded joint of reduced-activation ferritic steel for evaluating the distribution of high-temperature strength in the joint. The experimental results revealed that the distribution of the maximum load measured by the SP test at 873 K was very similar to that obtained from Vickers hardness, and the fusion zone was relatively devoid of high-temperature ductility. In addition, the ratio of the load of SP creep test to the stress of standard uniaxial creep test was calculated so that both the creep rupture curves were overlapped to convert the results of SP creep test into those of standard test. As a result, the ratio was determined to be 0.43 for the base metal and this load-stress conversion coefficient is in good agreement with that obtained from finite element analysis.