Study of fracture mechanisms of a Ni-Base superalloy at different temperatures

Purpose: The Ni-base superalloy GTD-111 gains its appropriate microstructure and high temperature strength through precipitation hardening mechanism. Because of their service condition, tensile properties of the alloy have strong influence on stability and life of the blades. Design/methodology/approach: Tensile fracture mechanisms of the cast and heat treated superalloy were studied over a wide range of temperatures from 25 to 950°C with a constant strain rate of 10-4s-1. The present paper provides structural and fractography evidence by means of scanning electron microscopy at different temperatures for the superalloy GTD-111. Findings: The variation in alloy ductility was found to correlate well with the fractography results of the tensile tested specimens. Transgranular and intergranular fracture with fine dimples, cleavage facets and a combination of them were shown in the fractographs. Research limitations/implications: Although tensile properties alone are important for the alloy, it is suggested for future research to work on the simultaneous effects of tension and fatigue on the fracture mechanisms. Originality/value: It was cleared that different fracture mechanisms operate in different temperature ranges; while transgranular dimple fracture was dominant at 650°C, the dominant fracture mechanism at room temperature was intergranular.