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

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 degrees 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 degrees 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 gamma and gamma' phases were determined and the results showed that, with increase of carbon content, the lattice parameters of gamma and gamma' 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.