Effect of Ultrasonic Nanocrystal Surface Modification on residual stress, microstructure and fatigue behavior of ATI 718Plus alloy

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:711

Article

Kattoura, Micheal¹  Telang, Abhishek¹  Mannava, Seetha Ramaiah¹  Qian, Dong²  Vasudevan, Vijay K.¹ 

[1] Univ Cincinnati, Dept Mech & Mat Engn, Cincinnati, OH 45221 USA

[2] Univ Texas Dallas, Dept Mech Engn, Richardson, TX 75080 USA

关键词: Ultrasonic Nanocrystal Surface Modification (UNSM);    Nickel-based superalloys;    Fatigue behavior;    Residual stresses;    Electron microscopy;    Characterization;   

DOI  :  10.1016/j.msea.2017.11.043

来源: Elsevier

【 摘 要 】

Ultrasonic Nanocrystal Surface Modification (UNSM) is a mechanical surface treatment that induces large compressive residual stresses and near-surface microstructural changes in the material using repetitive impacts at ultrasonic frequencies with a WC tip. In this study, we investigate the use of UNSM to improve the fatigue life of ATI718 Plus (718Plus). UNSM induced severe surface plastic deformation in 718Plus, which led to nano-sized crystallites, twins, and high dislocation density in the near surface regions, coupled with an increase in surface hardness by 2.3 GPa and high magnitude of compressive residual stresses. These changes increased the endurance limit by similar to 13% (similar to 100 MPa) in room temperature fatigue tests. This improvement in fatigue life was attributed to near-surface microstructural changes, material hardening and high compressive residual stress induced by UNSM. The crack propagation rates were 66% lower for UNSM-treated 718Plus as compared with untreated material. The residual stress relaxation after cyclic loading indicates the effectiveness of UNSM in improving the fatigue life of 718Plus.

【 授权许可】

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