Characterization of the Cold Ductility Degradation after Aging of aCentrifugally Cast 20Cr32Ni+Nb Alloy

摘要

The mechanical properties (yield stress, ultimate tensile stress and elongation) of alloy20Cr32Ni+Nb subject to isochronal aging at temperatures between 670 and 820℃ for 200h wereinvestigated using samples extracted from a centrifugally cast tube. The results confirm theoccurrence of embrittlement in the aged samples, with maximum embrittlement observed around770℃ without significant gain in strength. Analysis of the fracture surface shows that the crack pathis interdendritic at low magnification, but that dimples are observed at a finer scale. No majorchange in fracture morphology could be identified as origin of the ductility degradation observed forthe aged samples. No indications of the so-called “G phase” could be found either.