Effect of orientation on the tensile and creep properties of coarse-grained INCONEL alloy MA754

Elevated temperature tensile and creep-rupture tests were performed on INCONEL MA754 in longitudinal and transverse orientations at temperatures from 700°C to 1000°C. The transerve orientation was weaker and less ductile than the longitudinal orientation due to a higher grain boundary density perpendicular to the applied stress axis. This effect was especially pronounced in creep tests at 900°C and 1000°C. Threshold creep behavior was observed for the longitudinal orientation, with stress exponents ranging from 29 to 40. Stress exponents in the long transverse orientation ranged from 24 at 800°C to 5 at 1000°C, indicating a temperature-varying deformation mechanism. Creep ductility in the transverse orientation was extremely low, less than 1 pct for higher temperature, lower stress conditions. Failure in all transverse specimens was controlled by grain boundary separation. Even in the relatively weak transverse direction, the strength of MA754 compares favorably with other alloys being considered for advanced power plant applications.