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Environmental protection of titanium alloys in centrifugal compressors at 500°C in saline atmosphere

Béguin, Jean-Denis and Faure, Pierre and Adrian, Denise and Alexis, Joël and Petit, Jacques-Alain and Belaygue, Philippe and Fournier, Dominique Environmental protection of titanium alloys in centrifugal compressors at 500°C in saline atmosphere. (2004) Surface Engineering, 20 (2). 135-138. ISSN 0267-0844

(Document in English)

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Official URL: http://dx.doi.org/10.1179/026708404225010685


The use of the titanium alloy Ti-6246 (Ti–6Al–2Sn–4Zr–6Mo, wt-%) for gas turbine compressors allows an increase in working temperature and stress level. Under severe service conditions, the material experiences combined high temperature and high mechanical stress and, in saline atmospheres, stress corrosion cracking (SCC) can occur, leading to catastrophic mechanical failure. The present study was performed to evaluate the potential of several surface treatments to protect Ti-6246 alloy, after salt deposit, from hot salt SCC at temperatures ?500°C and 500 MPa static mechanical stress conditions. Shot peening, thermal oxidation and metal–ceramic coatings were investigated. Experimental results confirm the existence of brittle stress corrosion phenomena marked by a low residual elongation of test samples and the presence of oxides on the fracture surfaces. Both shot peening and metal–ceramic coatings increase the hot salt SCC resistance of the alloy. Times to rupture were improved by a factor of 3 for shot peening and by a factor of 10 for metal–ceramic coatings. Inversely, the time to rupture of preoxidised alloys has been halved compared with uncoated alloys. As well as these interesting quantitative results, structural studies of metal–ceramic coatings showed that they are mechanically and chemically compatible with the titanium alloy substructure and should work under severe thermomechanical stresses and aggressive atmospheres.

Item Type:Article
Additional Information:Thanks to Maney Publishing editor. The definitive version is available at : http://dx.doi.org/10.1179/026708404225010685
HAL Id:hal-00842830
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Other partners > Turbomeca (FRANCE)
Laboratory name:
Deposited On:15 Mar 2013 08:42

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