Fatigue cracking in gamma titanium aluminide

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

卷:798

Article

Trant, Claire F.¹  Lindley, Trevor C.¹  Martin, Nigel²  Dixon, Mark²  Dye, David¹ 

[1] Imperial Coll, Dept Mat, Royal Sch Mines, Prince Consort Rd, London SW7 2BP, England

[2] Rolls Royce PLC, POB 31, Derby DE24 8BJ, England

关键词: Fatigue;    Intermetallics;    Electron microscopy;    TiAl;    Borides;    Temperature effects;   

DOI  :  10.1016/j.msea.2020.140202

来源: Elsevier

【 摘 要 】

Cast and HIP'ed gamma-TiAl 4522XD is being developed for use in jet engine low pressure turbine blades, where temperature variations occur through the flight cycle. The effects of temperature variations on fatigue cracking were therefore examined in this study. It was found that fatigue crack growth rates were higher at 750 degrees C than 400 degrees C, but that Delta Kth was also higher. Temperature excursions between 400 and 750 degrees C during fatigue crack growth resulted in retardation of the crack growth rate, both on heating and cooling. It was also found that for notches 0.6 mm in length and smaller, initiation from the microstructure could instead be observed at stresses similar to the material failure stress; a microstructural initiation site exists. A change from transto mixed trans-, inter- and intra-lamellar cracking could be observed where the estimated size of the crack tip plastic zone exceeded the colony size.

【 授权许可】

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