PSI - Issue 19

Available online at www.sciencedirect.com Available online at www.sciencedirect.com

ScienceDirect ScienceDirect

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2019) 000 – 000 Structural Integrity Procedia 00 (2019) 000 – 000

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 19 (2019) 538–547

Fatigue Design 2019 Effect of temperature condition on short crack propagation in a single crystal Ni-base superalloy under thermomechanical fatigue Yasuhiro Yamazaki a , * , Maiki Miura a a Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 2683-8522, Japan Fatigue Design 2019 Effect of temperature condition on short crack propagation in a single crystal Ni-base superalloy under thermomechanical fatigue Yasuhiro Yamazaki a , * , Maiki Miura a a Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 2683-8522, Japan This study investigated the behaviors of short cracks in a single crystal Ni-base superalloy under the thermo-mechanical loading. The effect of temperature condition on the propagation behavior of short crack was discussed taking into account of crack closure. The experimental results indicated that the short crack growth rates under the higher temperature condition are remarkably higher than those under the lower temperature condition even if the crack closure and the temperature dependence on the deformation resistance take into consideration. Based on the crack propagation mechanism, the summation law of the crack propagation rates controlled with the mechanical and environmental factors was proposed to predict the fatigue short crack propagation rate. It was found that the experimental results can be predicted with good accuracy by the proposed method. is study inv stigated the behaviors of short cracks in a single crystal Ni-base superalloy under the thermo-mechanical loading. ffect of temperature condition on t e propagation behavior of short crack was discussed taking into account of cr ck closure. The experimental results indicated that the short crack growth rates under the higher t r t r condition are remarkably higher than those under the lower temperatur c dition even if the crack closure and the temperature dependence on the deformation resistance take into consideration. Based on the crack propagation mechanism, the summation law of the crack propag tion rates c ntrolled with the mechanical and environmental factors was proposed to pr dict the fatigue short crack propagation rate. It was found that the experimental results can be predicted with good accuracy by the proposed method. Abstract Abstract

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. Keywords: Short crack; Propagation; Thermo-mechanical fatigue; Oxidation effect Keywords: Short crack; Propagation; Thermo-mechanical fatigue; Oxidation effect

1. Introduction 1. Introduction

Ni-base superalloys have been used with high reliability for blades and vane applications in gas turbine system used as electrical generators and aero-engines. Because of the efficiency and performance of gas turbines can be improved by increasing the operating gas temperatures, the operating gas temperature has been increasing and increasing. By applying the directionally solidified superalloy and single crystal one to the turbine blade and vane materials, the heat resistant temperature of has been improved up to 1000℃ or higher. However, the inner and outer cooling system and the thermal barrier coatings are essential requirements for the hot section components (Kuwabara Ni-base superalloys have been used with high reliability for blades and vane applications in gas turbine system used as electrical generators and aero-engines. Because of the efficiency and performance of gas turbines can be improved by increasing the operating gas temperatures, the operating gas temperature has been increasing and increasing. By applying the directionally solidified superalloy and single crystal one to the turbine blade and vane materials, the heat resistant temperature of has been improved up to 1000℃ or higher. However, the inner and outer cooling system and the thermal barrier coatings are essential requirements for the hot section components (Kuwabara

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. * Correspon ing author. Tel.: +81-43-290-3208; fax: +81-43-290-3909. E-mail address: Y.yamazaki@chiba-u.jp * Corresponding author. Tel.: +81-43-290-3208; fax: +81-43-290-3909. E-mail address: Y.yamazaki@chiba-u.jp

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 10.1016/j.prostr.2019.12.058