The Effects of Carbon Content on the Microstructure and 650°C Tensile Properties of Incoloy 901 Superalloy

Abstract The microstructure and tensile properties of Incoloy 901 superalloy with various contents of carbon (0.02–0.09 wt%) were studied and a proper amount of carbon was determined to achieve good tensile properties at 650°C. The alloys were produced by vacuum induction melting and electro-slag refining (VIM+ESR) process and then they were hot rolled. After heat treatment, microstructures and 650°C tensile properties of specimens were investigated. Phase analysis with X-ray diffraction (XRD) indicated that Incoloy 901 contained Metallic carbides (MC)-type carbide enriched with Ti and Mo. With increasing carbon content from 0.02 to 0.09 wt%, carbide area fraction increased from 0.73% to 1.2%. Also, increasing of carbon content gave rise to higher amounts of carbide sizes. Using XRD patterns, the lattice parameters of γ and γ ′ phases were determined and the results showed that, with increase of carbon content, the lattice parameters of γ and γ ′ phases decreased and the mismatch between them increased from 0.119% for alloy containing 0.02 wt% to 0.167% for alloy containing 0.09 wt% C. The maximum strength of the alloy was obtained at 0.05 wt% carbon and ductility decreased slightly with increasing carbon.