A Deformation Mechanism Map for Incoloy 800H Optimized Using the Genetic Algorithm

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 50; no. 9; pp. 4098 - 4110
• Main Authors: Beardsley, Aaron L., Bishop, Catherine M., Kral, Milo V.
• Format: Journal Article
• Language: English
• Published: New York Springer US 15.09.2019; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Creep (materials); Deformation mechanisms; Ferrous alloys; Genetic algorithms; Grain size; High temperature; Iterative methods; Materials Science; Metallic Materials; Nanotechnology; Nickel base alloys; Optimization; Structural Materials; Superalloys; Surfaces and Interfaces; Test procedures; Thin Films
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-019-05350-6

A total of fifty-eight Incoloy 800H samples were creep tested between temperatures of 1023 K and 1293 K, stresses of 14.1 to 105 MPa, and average grain sizes of 87.7 to 315 µ m. Combined with data obtained by the National Institute for Materials Science (NIMS), a deformation mechanism map (DMM) for Incoloy 800H was produced. Optimization of the fit of the constitutive creep equations to the experimental data was performed using a global search iterative numerical optimization tool called a genetic algorithm (GA). It was found that the data were well represented by both high-temperature and low-temperature power-law creep mechanisms, but the extent of the influence of diffusion-based creep mechanisms, most specifically Coble creep, will require further investigation. A training and test method was performed to validate the solution and to test the extrapolability of the dataset. It was determined that the extrapolability of the data in all directions of the DMM was generally low.