Use of the small punch test to determine the ductile-to-brittle transition temperature of structural steels

摘要

The small punch test (SPT) consists in punching very small square specimens, measuring 10 × 10 mm~2 and 0.5-mm thickness, until fracture using a 2.5-mm-diameter hemispherical punch. Different specimens of a structural steel were tested from room temperature to cryogenic temperatures in order to determine its ductile-to-brittle transition temperature (DBTT). The DBTT obtained in SPT (DBTTstp) is much lower than the DBTT obtained by means of Charpy specimens (DBTT_(CVN)). The variation of the mechanical parameters calculated from the SPTs with temperature was also calculated and the operative fracture micromechanisms defined using a scanning electron microscope.