Characterisation of microstructure and creep properties of alloy 617 for high-temperature applications

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2014-12, Vol.619, p.77-86
• Main Authors: Di Martino, S.F., Faulkner, R.G., Hogg, S.C., Vujic, S., Tassa, O.
• Format: Article
• Language: English
• Subjects: Applied sciences; Creep; Creep (materials); Cross-disciplinary physics: materials science; rheology; Deformation, plasticity, and creep; Exact sciences and technology; Heat treatment; INCONEL 617; Materials science; Materials selection; Mathematical models; Mechanical properties and methods of testing. Rheology. Fracture mechanics. Tribology; Metals. Metallurgy; Microstructural evolution; Microstructure; Modelling; Ni-base alloys; Nickel base alloys; Other heat and thermomechanical treatments; Physics; Precipitates; Precipitation; Production techniques; Superalloys; Thermomechanical treatment; Treatment of materials and its effects on microstructure and properties; Ultra-supercritical power plant
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2014.09.046

Current energy drivers are pushing research in power generation materials towards improved efficiency and improved environmental impact. In the context of new generation ultra-supercritical (USC) power plant, this is represented by increased efficiency, service temperature reaching 750°C, pressures in the range of 35–37.5MPa and associated carbon capture technology. Ni base alloys are primary candidate materials for long term high temperature applications such as boilers. The transition from their current applications, which have required lower exposure times and milder corrosive environments, requires the investigation of their microstructural evolution as a function of thermo-mechanical treatment and simulated service conditions, coupled with modelling activities that are able to forecast such microstructural changes. The lack of widespread microstructural data in this context for most nickel base alloys makes this type of investigation necessary and novel. Alloy INCONEL 617 is one of the Ni-base candidate materials. The microstructures of four specimens of this material crept at temperatures in the 650–750°C range for up to 20,000h have been characterised and quantified. Grain structure, precipitate type and location, precipitate volume fraction, size and inter-particle spacing have been determined. The data obtained are used both as input for and validation of a microstructurally-based CDM model for forecasting creep properties.