EFFECTS OF NEUTRON-IRRADIATION AND HYDROGEN ON DUCTILE-BRITTLE TRANSITION-TEMPERATURES OF V-CR-TI ALLOYS

The effects of neutron irradiation and hydrogen on the ductile-brittle transition temperatures (DBTTs) of unalloyed vanadium and V-Cr-Ti alloys were determined from Charpy-impact tests on 1/3 ASTM-standard-size specimens and from impact tests on 3-mm diameter discs. The tests were conducted on specimens containing < 30 appm hydrogen and 600-1200 appm hydrogen and on specimens after neutron irradiation to 28-46 atom displacements per atom at 420, 520, and 600 degrees C. The DBTTs were minimum (< -220 degrees C) for V-(1-5)Ti alloys and for V-4Cr-4Ti alloy with < 30 appm hydrogen. The effect of 600-1200 appm hydrogen in the specimens was to raise the DBTTs by 60-100 degrees C. The DBTTs were minimum (< -200 degrees C) for V-(3-5)Ti and V-4Cr-4Ti alloys after neutron irradiation.