Room-temperature ductility and surface notch sensitivity of chromium alloyed with vanadium and molybdenum

The ductility at room temperature was investigated with pure Cr, Cr–V and Cr–Mo alloys from the view of surface energy and shear modulus. The surface energy, γ, was qualitatively evaluated by the creep method using thin plate specimens. The specimen contraction during creep was observed only when the low stress was applied to Cr–0.5 mol%V and Cr–0.2 mol%Mo alloys. This indicated that the γ value was highest in these alloys among the other compositional alloys as well as pure Cr; although the reason still remained unknown. On the other hand, the shear modulus, G, was measured using the cantilever-type resonating method. It decreased monotonously with the V or Mo content in the alloys. Thus, the G/γ ratio was supposed to be smaller in Cr–0.5 mol%V and Cr–0.2 mol%Mo alloys than in pure Cr. In response to this change in the G/γ ratio, the ductility measured by the three-point bending test was high in these alloys. Nevertheless, the overall ductility change with alloying could not be explained by the G/γ ratio alone.