Prediction of plastic strain for recrystallisation during investment casting of single crystal superalloys

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Colleges, School and Institutes

External organisations

  • University of Cambridge
  • Rolls-Royce plc

Abstract

Castings for single crystal aerofoils can be prone to re-crystallisation during solution heat treatment; however quantitative information concerning the factors causing this phenomenon is lacking. In this paper, mathematical modelling and targeted experimentation are used to deduce the levels of localised plastic strain needed for recrystallisation to occur. The influences of differential thermal contraction against the shell, specimen geometry and stress concentration factor are quantified. The model predicts that the induced strain in the metal increased with the ceramic shell thickness, and in some geometries, with the solidification height. Negligible plastic strains were predicted in a solid casting with no stress concentration features. However, as the geometry became more complex by reducing the casting cross-section, by the insertion of a core and introduction of stress concentration features, the induced plastic strains increased significantly. The predicted plastic strain for recrystallisation in a cored casting was in good agreement with experimental critical strain data. The model provides the foundation for a systems-based approach which enables recrystallisation to be predicted and thus avoided, prior to its occurrence in the foundry.

Details

Original languageEnglish
Title of host publicationProceedings of the International Symposium on Superalloys
Publication statusPublished - 2012
Event12th International Symposium on Superalloys, Superalloys 2012 - Seven Springs, PA, United States
Duration: 9 Sep 201213 Sep 2012

Conference

Conference12th International Symposium on Superalloys, Superalloys 2012
CountryUnited States
CitySeven Springs, PA
Period9/09/1213/09/12

Keywords

  • Investment casting, Modelling, Plastic strain accumulation, Recrystallisation