Microstructural Evolution of Large Cast Haynes 282 at Elevated Temperature

Abstract

Haynes 282 has attracted attention for casting applications in AUSC power plants due to its good creep properties. However, the market is primarily comprised of wrought Haynes 282, while the cast version is not commercially available. In this study, the microstructure of a large traditional sand cast Haynes 282 was studied from as-cast condition to long-term heat-treated condition by combining experimental data and thermodynamic calculations. The microstructure of a large cast Haynes 282 includes γ, γ’, two types of MX, M23C6 and µ phases. After standard post heat treatment, µ phases were dissolved and precipitated as M6C. The equilibrium state was achieved after 266 h aging at 788 °C, after which γ’ particles began coarsening. These kept to a spherical morphology; the smallest misfit was found with the γ matrix. Once post heat treatment was finished, MX exhibited little morphology and compositional change during the long-term isothermal aging. Grain boundary is covered by discrete M23C6 and M6C precipitates and this morphology keeps stable during isothermal aging. No presence of the needle µ phase have been found at grain boundaries after 10,000 h aging at 788 °C. All these microstructural features indicated that cast Haynes 282 could have a high thermal stability and good creep properties.

The Impact of Plastic Deformation on the Microstructure and Tensile Strength of Haynes 282 Nickel Superalloy Produced by DMLS and Casting

“…These treatments can help inhibit the formation of large Ti-rich MX. It is important to reduce the amount of Ti-rich CX type carbides because Ti is the component of the main strengthening phase γ′ of the alloy [ 28 ].…”

Effect of the Addition of Re on the Microstructure and Phase Composition of Haynes 282: Ab Initio Modelling and Experi-Mental Investigation of Additively Manufactured Specimens

“…However, molybdenum was chosen to be included in the model. It plays a vital role in defining the creep properties of Haynes 282 [1] while also influencing the phase stability of Ni-based superalloys, i.e., leading to µ phase formation [22]. Because both Al and Ti mainly enrich the gamma L1 2 -Ni 3 (Al, Ti) phase in Ni-based superalloys [23] and occupy similar positions in its crystal structure [17], the concentration of Al was set as a sum of Al and Ti fractions in the Haynes 282 alloy.…”

Effect of the Addition of Re on the Microstructure and Phase Composition of Haynes 282: Ab Initio Modelling and Experimental Investigation of Additively Manufactured Specimens

“…However, molybdenum was chosen to be included in the model. It plays a vital role in defining the creep properties of Haynes 282 [ 1 ] while also influencing the phase stability of Ni-based superalloys, i.e., leading to μ phase formation [ 22 ]. Because both Al and Ti mainly enrich the gamma L1 2 -Ni 3 (Al, Ti) phase in Ni-based superalloys [ 23 ] and occupy similar positions in its crystal structure [ 17 ], the concentration of Al was set as a sum of Al and Ti fractions in the Haynes 282 alloy.…”

“…It is worth n higher percentage of Co than Mo in Haynes 282 (10 and 8.5 wt%, resp molybdenum was chosen to be included in the model. It plays a vita creep properties of Haynes 282 [1] while also influencing the phase superalloys, i.e., leading to µ phase formation [22]. Because both Al a the gamma L12-Ni3(Al, Ti) phase in Ni-based superalloys [23] and occu in its crystal structure [17], the concentration of Al was set as a sum o in the Haynes 282 alloy.…”