Effects of alloying and processing on ultrasonic fatigue behavior in binary Ti-Al alloys

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

卷:756

Article

Shi, Qianying¹  Hsiel, Sinsar A.^1,2  Jones, J. Wayne¹  Allison, John E.¹ 

[1] Univ Michigan, Dept Mat Sci & Engn, Ann Arbor, MI 48109 USA

[2] Aerojet Rocketdyne, Met, Jupiter, FL 33478 USA

关键词: Titanium alloys;    Ultrasonic fatigue;    Small crack growth;    Electron microscopy;    EBSD;   

DOI  :  10.1016/j.msea.2019.03.079

来源: Elsevier

【 摘 要 】

Three model binary Ti-Al alloys with single a phase were investigated in this study to develop a fundamental understanding of high cycle and very high cycle fatigue behavior in a-titanium, alloys. Ultrasonic fatigue instrumentation with a cyclic frequency of nominally 20 kHz was used for fully reversed loading fatigue testing and combined with customized optical microscopy to study small crack growth from artificial cracks initiated at micro-notches produced by focused ion beam. Fractography showed the formation of low AK facets with different features near the crack initiation sites. Micro-beach marks were observed to form on some facets which could be correlated with the spatial angle between facet normal and loading direction. Aluminum content and processing (forging/rolling history) were found to have no significant effect on the small crack growth behavior of the studied alloys. Different crack growth models were compared and discussed to estimate the fatigue performance, especially for cross-rolled Ti-4Al alloy with void-type defects.

【 授权许可】

Free