Creep of a Nickel-Base Directionally Solidified Alloy Under Combined Tension and Torsion

Abstract

Combined tension-torsion creep tests of directionally solidified IN738LC are performed at 850°C using thin-walled tubular specimens with their axes coincident with the direction of solidification. It is observed that equivalent creep-rate depends markedly on the ratio of shear stress to tensile stress under constant equivalent stresses of Mises, while non-coaxiality between stress and creep-rate is rather small. It is shown that the experiments are simulated well, if the {100} <110> cubic system is combined with the {111} <110> or {111} <112> octahedral system; i.e., the former is active in shear creep, while the latter in tensile creep.