Effects of secondary orientations on long fatigue crack growth in a single crystal superalloy

Zhang, Yangyang; Qiu, Wenhui; Shi, Hui‐Ji; Li, Changpeng; Kadau, Kai; Luesebrink, Oliver

doi:10.1016/j.engfracmech.2015.01.027

Cited by 31 publications

(8 citation statements)

References 26 publications

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“…They observed crystallographic cracking in all tests at room temperature, whereas tests at elevated temperature showed non-crystallographic cracking in the beginning of the tests with a transition to partly crystallographic cracking in some of the elevated temperature tests. The influence of crystal orientation on the fatigue crack growth behaviour of single crystal nickel base superalloys was also studied by Okazaki et.al 74 and Zhang et al 75 .…”

Section: Fatigue Crack Propagation Of Single Crystal Superalloysmentioning

confidence: 95%

“…The crack growth behaviour of single crystal superalloys under isothermal conditions has been previously studied [65][66][67][68][69][70][71][72][73][74][75][76][77][78][79][80] , although uncertainties still remain regarding the phenomenon of crystallographic crack growth. The localization of inelastic deformation to {111} planes and crystallographic crack growth along these planes provides a major challenge in terms of test data evaluation and crack growth modelling for single crystal superalloys.…”

Section: Summary Of Findingsmentioning

confidence: 99%

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Crack growth in single crystal nickel base superalloys under isothermal and thermomechanical fatigue

Palmert

2019

Linköping Studies in Science and Technology. Licentiate Thesis

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This work concerns the fatigue crack growth behaviour of nickel base single crystal superalloys. The main industrial application of this class of materials is in gas turbine blades, where the ability to withstand severe mechanical loading in combination with high temperatures is required. In order to ensure the structural integrity of gas turbine blades, knowledge of the fatigue crack growth behaviour under service-like conditions is of utmost importance. The aim of the present work is both to improve the understanding of the crack growth behaviour of single crystal superalloys and also to improve the testing and evaluation methodology for crack propagation under thermomechanical fatigue loading conditions. Single crystal superalloys have anisotropic mechanical properties and are prone to localization of inelastic deformation along the close-packed planes of the crystal lattice. Under some conditions, crystallographic crack growth occurs along these planes and this is a complicating factor throughout the whole chain of crack propagation life simulation; from material data generation to component calculation. Fatigue crack growth testing has been performed, both using conventional isothermal testing methods and also using thermomechanical fatigue crack growth testing. Experimental observations regarding crystallographic crack growth have been made and its dependence on crystal orientation and testing temperature has been investigated. Quantitative crack growth data are however only presented for the case of Mode I crack growth under isothermal as well as thermomechanical fatigue conditions. Microstructural investigations have been undertaken to investigate the deformation mechanisms governing the crack growth behaviour. A compliance based method for the evaluation of crack opening force under thermomechanical fatigue conditions was developed, in order to enable a detailed analysis of the test data. The crack opening force evaluation proved to be of key importance in the understanding of the crack driving force under different testing conditions. vi vii

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Section: Fatigue Crack Propagation Of Single Crystal Superalloysmentioning

confidence: 95%

Section: Summary Of Findingsmentioning

confidence: 99%

Crack growth in single crystal nickel base superalloys under isothermal and thermomechanical fatigue

Palmert

2019

Linköping Studies in Science and Technology. Licentiate Thesis

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“…One particular aspect complicating the understanding of the behaviour of singlecrystal materials is the dependency on the crystallographic orientation, which influences the stress state and thus the fracture behaviour [19,29]. Hence, the material response is strongly coupled to the crystallographic orientation [17,[29][30][31][32][33][34] and it is thus crucial to be able to accurately determine it. Often only the primary orientation is accounted for during the casting procedure, while the secondary orientation is not determined.…”

Section: Single-crystal Nickel-base Superalloysmentioning

confidence: 99%

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

Busse

2019

Linköping Studies in Science and Technology. Dissertations

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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. Thank you! Linköping, December 2019 Christian Busse iii The nature of science is not that of a steady, linear progression toward the truth, but rather a tortuous road, often characterized by dead ends and U-turns, and yet ultimately inching toward a better, if tentative, understanding of the natural world.

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“…Nickel-based single crystal superalloys have excellent high-temperature mechanical properties and are the preferred materials for aero-engine and gas turbine blades [1]. Due to the anisotropy of mechanical properties, the single crystal blade has the best service performance when the <001> direction of the crystal is consistent with the maximum stress direction [2]. Directional solidification investment casting, combined with grain selection or seeding technology, is the main method for preparing single crystal blades [3,4].…”

Section: Introductionmentioning

confidence: 99%

Orientation Control for Nickel-Based Single Crystal Superalloys: Grain Selection Method Assisted by Directional Columnar Grains

Zhao

Bai

et al. 2022

Materials

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The service performance of single crystal blades depends on the crystal orientation. A grain selection method assisted by directional columnar grains is studied to control the crystal orientation of Ni-based single crystal superalloys. The samples were produced by the Bridgman technique at withdrawal rates of 100 μm/s. During directional solidification, the directional columnar grains are partially melted, and a number of stray grains are formed in the transition zone just above the melt-back interface. The grain selected by this method was one that grew epitaxially along the un-melted directional columnar grains. Finally, the mechanism of selection grain and application prospect of this grain selection method assisted by directional columnar grains is discussed.

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Effects of secondary orientations on long fatigue crack growth in a single crystal superalloy

Cited by 31 publications

References 26 publications

Crack growth in single crystal nickel base superalloys under isothermal and thermomechanical fatigue

Crack growth in single crystal nickel base superalloys under isothermal and thermomechanical fatigue

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

Orientation Control for Nickel-Based Single Crystal Superalloys: Grain Selection Method Assisted by Directional Columnar Grains

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