Design of polycrystalline superalloys

F. Tancret, E. Bertrand

This is our most ancient activity (started in 1998), which was the frame of the development of a large part of our skills on computational alloy design (data mining / machine learning, physical models including computational thermodynamics, multi-objective optimisation by genetic algorithm…), and that led to numerous pioneering papers in the domain and to the most integrated method to date. Examples of achievements are presented below.

 Keywords: Neural networks, Gaussian processes, Calphad, Thermo-Calc, weldable

 

 

Below is an example (PhD thesis of Edern Menou) of works undertaken as a collaboration with Aubert&Duval company. Many Pareto-optimal alloys were designed, optimising simultaneously the yield stress (vertical axis) and the ultimate tensile stress (horizontal axis) at high temperature, the creep resistance (colour code on the right) and the cost (size of bubbles). The comparison with a last generation commercial alloy shows potential gains on certain characteristics, or even on all of them simultaneously (example of alloy “C”).

 

An alloy has been selected, fabricated and characterised. It displays the desired microstructure (austenitic matrix + intermetallic precipitates γ’ + carbides), mechanical properties superior to those of the concurrent alloy, while allowing a significant reduction in cost.

 

Another example deals with the exploitation of a physical model for dynamic recrystallisation (DRX) allowing, in addition to the maximisation of the mechanical properties of alloys, to take into account their response to forging so as to optimise processing conditions (minimisation of temperature) and microstructure (minimisation of the strain necessary to provoke full recrystallisation, minimisation of the final grain size).

 

References:

F. Tancret, H.K.D.H. Bhadeshia, D.J.C. MacKay, “Design of a creep resistant nickel base superalloy for power plant applications: Part 1 – Mechanical properties modelling”, Materials Science and Technology, 19(3) (2003) 283-290

F. Tancret, H.K.D.H. Bhadeshia, “Design of a creep resistant nickel base superalloy for power plant applications: Part 2 – Phase diagram and segregation simulation”, Materials Science and Technology, 19(3) (2003) 291-295

F. Tancret, T. Sourmail, M.A. Yescas, R.W. Evans, C. McAleese, L. Singh, T. Smeeton, H.K.D.H. Bhadeshia, “Design of a creep resistant nickel base superalloy for power plant applications: Part 3 – Experimental results”, Materials Science and Technology, 19(3) (2003) 296-302

F. Tancret, M. Bellini, “Properties, processability and weldability of a novel affordable creep-resistant nickel base superalloy”, Materials Science and Technology, 24(4) (2008) 479-487

F. Tancret, “Computational thermodynamics and genetic algorithms to design affordable gamma’-strengthened nickel-iron based superalloys”, Modelling and Simulation in Materials Science and Engineering, 20 (2012) 045012 (6 pp)

F. Tancret, “Computational thermodynamics, Gaussian processes and genetic algorithms: combined tools to design new alloys”, Modelling and Simulation in Materials Science and Engineering, 21 (2013) 045013 (9 pp)

E. Menou, G. Ramstein, E. Bertrand, F. Tancret, “Multi-objective constrained design of nickel-base superalloys using data mining- and thermodynamics-driven genetic algorithms”, Modelling and Simulation in Materials Science and Engineering, 24 (2016) 055001 (25pp)

F. Tancret, E. Galindo-Nava, P.E.J. Rivera Díaz-del-Castillo, “Dynamic recrystallisation model in precipitation-hardened superalloys as a tool for the joint design of alloys and forming processes”, Materials & Design, 103 (2016) 293-299

 

Collaborations:

. Laboratoire des Sciences du Numérique de Nantes (LS2N) – Université de Nantes
. Aubert&Duval