MULTI-SCALE MODELING OF AGING OF WASPALOY SUPERALLOY: PREDICTION OF MICROSTRUCTURE EVOLUTION AND COUPLING WITH MECHANICAL PROPERTIES

Date

2024-1-17

Author

Gövercin, Betül

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Ni-based superalloys operating under high temperatures, ensuing compression and tension type of loads, and highly corrosive environment are mostly used in tubine engines. In order to provide high temperature strength needed for operational conditions, heat treatment processes are crucial for those materials. Therefore, modelling of processes according to required microstructure and properties have a great importance for aerospace and power plant industries to reduce the number of time-consuming and highly costing manufacturing operations. In this study, effect of heat treatment on Waspaloy is investigated starting from solidification to implementation on mechanical properties. Solidification modelling is constituted with CALPHAD method by using PANDAT. Offered and applied heat treatment process is designed by using thermodynamic and kinetic models and the results are compared with SEM, TEM and EDS outcomes. Model results are used for yield strength estimation comprising precipitation, solid solution, Orowan, coherency and grain size hardening at varying temperatures. Aged specimens are subjected to tensile tests at room temperature, 580°C, 650°C, 720°C and 1100°C with Gleeble 3500 system. The generic approach applied in this study has given that the modelled heat treatment and experimental study are both shown ɣ' precipitate sizes with approximately 25 nm. Yield strength estimation constructed with the modelling results has shown 1-8 percent variation from the experimental results at room and elevated temperatures whereas in 1100°C condition, predictions differed greatly. Therefore, it is declared that this model can predict the yield strength of the material but needs further developments to predict all conditions accurately.

Subject Keywords

Waspaloy, Heat Treatment, Ni-based superalloy, Pandat, Modelling

URI

https://hdl.handle.net/11511/108511

Collections

Graduate School of Natural and Applied Sciences, Thesis