Aging behavior of Haynes® 282® wrought nickel superalloy subjected to a cold pre-deformation by differential speed rolling

Abstract

The mechanical response of Haynes® 282®, a wrought gamma prime strengthened nickel-based superalloy, is tailored by using both a cold deformation processing and a post-straining heat treatment including a two-step aging. In this work, the effect of the applied cold pre-deformation by conventional equal speed rolling (ESR) or differential speed rolling (DSR) methods on the aging behavior of Haynes® 282® superalloy, is examined for the first time. For this reason, the solid solution annealed alloy was subjected to ~50% nominal cold thickness reduction by either ESR or DSR methods, followed by a two-step heat treatment at 1010 °C/2 h and 780 °C/8 h. The material’s structural evolution on each processing step was characterized by using scanning electron microscopy/electron backscatter diffraction and transmission electron microscopy methods. Corresponding mechanical properties were examined in static tensile tests performed on non-standard miniaturized specimens. It was found that, the introduction of a shear strain by rolls speed differentiation in the cold-rolling process results in an (I) more efficient strain-hardening of the alloy in the as-deformed state and (II) an intensive grain-refinement upon the post-deformation annealing. Consequently, the DSR provides a higher room temperature mechanical strength obtained in both aging steps, as compared to the non-deformed and conventionally cold-rolled counterparts. Furthermore, noticeable differences in terms of stability of crystallographic orientations for ESRed or DSRed and heat-treated alloy, were noted.