Creep and Stress Relaxation Anisotropy of a Single-Crystal Superalloy

Segersäll, Mikael; Moverare, Johan; Leidermark, Daniel; Simonsson, Kjell

doi:10.1007/s11661-014-2198-0

Cited by 22 publications

(9 citation statements)

References 40 publications

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“…Compared to creep test data, stress relaxation data for superalloys is sparse [1,2,[8][9][10] and especially rare for single crystal alloys [2,9,10]. Test durations at constant strain beyond 24 h are essential for a higher fidelity design of the high temperature seals, but such data are absent.…”

Section: Introductionmentioning

confidence: 99%

Stress relaxation behavior in single crystal superalloys

Nathal¹,

Bierer²,

Evans³

et al. 2015

Materials Science and Engineering: A

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Section: Introductionmentioning

confidence: 99%

Stress relaxation behavior in single crystal superalloys

Nathal¹,

Bierer²,

Evans³

et al. 2015

Materials Science and Engineering: A

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“…Therefore, it is not believed that the serrated yielding occurs due to twinning in this case. Instead, previous studies [10,11] have reported of a serrated yielding behaviour for the 011 direction, and it was discussed that dynamic strain ageing has occurred and also that only one slip system is active during plastic deformation in the 011 direction. If a serrated yielding behaviour during the first cycles will influence the TMF life has not been considered in this paper, but this may be of interest for future research.…”

Section: The Tmf Behaviourmentioning

confidence: 98%

In- and out-of-phase thermomechanical fatigue of a Ni-based single-crystal superalloy

Segersäll

Moverare

Leidermark

et al. 2014

MATEC Web of Conferences

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Abstract. In this study, the difference between in-phase (IP) and out-of-phase (OP) thermomechanical fatigue (TMF) cycling from 100 to 750• C has been investigated for the Ni-based single-crystal superalloy MD2. In addition, two different crystal orientations were studied, the 001 and 011 orientations respectively. When comparing IP and OP TMF lives, a strain range dependency is found for the 001 direction. For high strain ranges, IP cycling leads to a higher number of cycles to failure compared to OP. However at lower strain ranges, OP cycling leads to a higher number of cycles to failure compared to IP. Microstructure investigation shows that for the 001 direction, deformation twinning within the γ /γ -microstructure is much more pronounced during OP conditions compared to IP. However for the 011 direction, the opposite is observed; twinning is more pronounced during IP TMF. From the microstructure investigation it is also visible that intersections between twins seems to trigger formation of TCP phases and recrystallization. These intersections also work as initiation points for TMF damage.

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“…These components are often cast from nickel-base superalloys in the form of singlecrystals. The material anisotropy of single-crystal materials adds an extra dimension of complexity to the modelling, testing and understanding of the fracture mechanisms [3][4][5][6][7][8][9][10][11]. The service life of many hot components is not fully restricted by the number of cycles to crack initiation, which means that a certain amount of crack propagation is allowed before the component has to be replaced in service.…”

Section: Zusammenfassungmentioning

confidence: 99%

Aspects of Crack Growth in Single-Crystal Nickel-Base Superalloys

Busse¹

2017

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Linköping, December 2017Cover: Front: Anisotropic stress response of an FE-simulation of an uncracked DCT specimen. Back: Stress response at the crack tip of an FE-simulation of a cracked DCT specimen.Printed by: LiU-Tryck, Linköping, Sweden, 2017 ISBN: 978-91-7685-395-5 ISSN: 0280-7971 Distributed by: Linköping University Division of Solid Mechanics SE-581 83 Linköping, Sweden © 2017 Christian Busse This document was prepared with L A T E X, November 14, 2017 No part of this publication may be reproduced, stored in a retrieval system, or be transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior permission of the author. PrefaceThe work presented in this Licentiate of Engineering thesis has been generated at the Division of Solid Mechanics at Linköping Universtiy and is part of the research project KME-702. The research has been funded by the Swedish Energy Agency and Siemens Industrial Turbomachinery AB through the Research Consortium of Materials Technology for Thermal Energy Processes, the support of which is greatly acknowledged. The research project concerns the fields of mechanical testing, microstructure investigations and modelling. This variety gave me the opportunity to learn something new in many different fields almost every day.This Furthermore, I would like to thank my friend and fellow PhD student J-L, who helped me with many fruitful discussions and makes the PhD life more joyful.Finally, I would like to thank Nathalie, who, even though we had to part ways, has always supported me and was always there for me. In a way, I am where I am today because of you. I will always be grateful for that and I will never forget you. Thank you! AbstractThis Licentiate of Engineering thesis is a product of the results generated in the research project KME-702, which comprises modelling, microstructure investigations and material testing of cast nickel-base superalloys.The main objective of this work is to model the fatigue crack propagation behaviour in single-crystal nickel-base superalloys. To achieve this, the influence of the crystal orientations on the cracking behaviour is assessed. The results show that the crystal orientation is strongly affecting the material response and must be accounted for. Furthermore, a linear elastic crack driving force parameter suitable for describing crystallographic cracking has been developed. This parameter is based on resolved anisotropic stress intensity factors and is able to predict the correct crystallographic cracking plane after a transition from a Mode I crack. Finally, a method to account for inelastic deformations in a linear elastic fracture mechanics context was investigated. A residual stress field is extracted from an uncracked finite-element model with a perfectly plastic material model and superimposed on the stress field from the cracked model with a linear elastic material model to account for the inelastic deformations during the determination of the crack driving force. The modellin...

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Creep and Stress Relaxation Anisotropy of a Single-Crystal Superalloy

Cited by 22 publications

References 40 publications

Stress relaxation behavior in single crystal superalloys

Stress relaxation behavior in single crystal superalloys

In- and out-of-phase thermomechanical fatigue of a Ni-based single-crystal superalloy

Aspects of Crack Growth in Single-Crystal Nickel-Base Superalloys

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