## Overview about constitutive models for single crystal superalloys

- The technological importance, the regularity of the microstructure and the complexity of the mechanical behavior of single crystal superalloys have motivated the development of a large number of mathematical models of the mechanical behavior of these alloys in the last two decades. While crystal viscoplasticity has proven to be an efficient framework to account for their anisotropy, several issues are still challenging. Indeed, most models consider that octahedral and cubic slip systems contribute to the largest part of the plastic deformation. However, the exact nature of cubic slip is still controversial and the precipitates can be sheared by <112> slip systems at intermediate temperatures, which largely influence the dependence of the flow rate on the orientation under creep conditions. Due to the different strengths of the matrix and the precipitates and the large volume fraction of the precipitate phase, a complex distribution of internal stresses exists, which can difficultly beThe technological importance, the regularity of the microstructure and the complexity of the mechanical behavior of single crystal superalloys have motivated the development of a large number of mathematical models of the mechanical behavior of these alloys in the last two decades. While crystal viscoplasticity has proven to be an efficient framework to account for their anisotropy, several issues are still challenging. Indeed, most models consider that octahedral and cubic slip systems contribute to the largest part of the plastic deformation. However, the exact nature of cubic slip is still controversial and the precipitates can be sheared by <112> slip systems at intermediate temperatures, which largely influence the dependence of the flow rate on the orientation under creep conditions. Due to the different strengths of the matrix and the precipitates and the large volume fraction of the precipitate phase, a complex distribution of internal stresses exists, which can difficultly be captured by the conventional back stress models of plasticity. In addition, at high temperature, the microstructure degrades and the residual mechanical strength is reduced. The driving force for this microstructure degradation is intimately connected to the distribution of the internal stresses. As a result of this complexity, a large number of tests are usually required to fully characterize the mechanical behavior of single crystal superalloys. This in turn largely impedes the implementation of inelastic modeling in the industrial praxis. The lecture summarizes the principal types of constitutive models for single crystal superalloys and reviews some recent advances in this area. In particular, it is shown how simulations at the microstructure scale level combined with conventional testing and microscopic analysis helped to improve our understanding of the mechanical behavior of single crystal superalloys. Directional coarsening, the importance of internal stresses, orientation dependency and the corresponding modeling issues are discussed. Also open questions are highlighted.…

Autoren/innen: | Bernard Fedelich |
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Koautoren/innen: | A. Epishin, Vitaliy Kindrachuk, Th. Link, A. Vattré |

Dokumenttyp: | Vortrag |

Veröffentlichungsform: | Präsentation |

Sprache: | Englisch |

Jahr der Erstveröffentlichung: | 2017 |

Organisationseinheit der BAM: | 5 Werkstofftechnik |

5 Werkstofftechnik / 5.2 Experimentelle und modellbasierte Werkstoffmechanik | |

DDC-Klassifikation: | Technik, Medizin, angewandte Wissenschaften / Ingenieurwissenschaften / Ingenieurwissenschaften und zugeordnete Tätigkeiten |

Freie Schlagwörter: | Constitutive law; Model; Single Crystal; Superalloy |

Themenfelder/Aktivitätsfelder der BAM: | Material |

Veranstaltung: | International Workshop on Modelling and Simulation of Superalloys |

Veranstaltungsort: | Bochum, Germany |

Beginndatum der Veranstaltung: | 27.03.2017 |

Enddatum der Veranstaltung: | 28.03.2017 |

Verfügbarkeit des Dokuments: | Datei im Netzwerk der BAM verfügbar ("Closed Access") |

Datum der Freischaltung: | 09.05.2017 |

Referierte Publikation: | Nein |