抄録
Toughness evaluation of narrow high-energy-beam welds by the conventional Charpy V-notch (CVN) impact test is not all successful because the crack often deviates from the fusion zone into the heat affected- or unaffected base metal-zones. The small-punch (SP) test was applied to the electron-beam welds of a steel with a 490 MPa yield strength to evaluate the toughness by measuring the ductile-brittle transition temperature (DBTT). The steel was electron-beam-welded with various heat-inputs and the welds were examined by Charpy V-notch and small-punch tests at 40-298 K. The SP-DBTTs obtained from the SP energy show a linear correlation with the CVN-DBTTs. The load-deflection curves during the small-punch tests and the fractography of small-punch tested specimens supported the ductile-brittle transitions. The results suggest that the small-punch test can be used to predict the DBTTs of the electron-beam welds, which cannot be accomplished by conventional Charpy V-notch impact tests.
