Effect of laser shock peening on the high temperature oxidation resistance of titanium

• Published in: Surface & coatings technology Vol. 326; pp. 146 - 155
• Main Authors: Kanjer, A., Lavisse, L., Optasanu, V., Berger, P., Gorny, C., Peyre, P., Herbst, F., Heintz, O., Geoffroy, N., Montesin, T., Marco de Lucas, M.C.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-10-2017; Elsevier
• Subjects: Chemical Sciences; High temperature oxidation; Laser shock peening; Material chemistry; Nitrogen insertion; Surface analysis; Titanium; Titanium; Laser shock peening; Nitrogen insertion; Surface analysis; High temperature oxidation
• ISSN: 0257-8972; 1879-3347
• DOI: 10.1016/j.surfcoat.2017.07.042

The effect of laser shock peening on the high temperature oxidation resistance of commercial pure titanium at high temperature (700°C) was studied in long-time (3000 h) exposure under dry air. A reduction of the gain mass by a factor 4 was found for laser-shock peened (LSP) samples compared to untreated titanium, which supports the interest of laser-shock treatment for the improvement of high temperature resistance. Short-durations (10h and 100h) oxidation experiments, devoted to investigate the influence of the LSP treatment on the first stages of the oxidation process, were also carried out by TGA. Several techniques as scanning electron microscopy, hardness and roughness measurements, X-ray diffraction and X-ray photoelectron spectrometry, micro-Raman spectroscopy, nuclear reaction analysis and electron backscattered diffraction were used to characterize the sample after laser treatment and oxidations. The formation of a continuous nitrogen-rich layer between the oxide layer and the α-case area in LSP samples appears to be the key factor to explain the reduction of oxygen diffusion, and thus the improvement of the oxidation resistance of laser shocked titanium. Moreover, the grain-texture of LSP samples after oxidation can also explain the improvement of the high temperature oxidation resistance after long times exposures.
•Laser shock peening (LSP) improves the high temperature oxidation resistance of pure titanium.•Four times smaller mass gain for LSP treated Ti after 3000h at 700°C in dry air.•The insertion of nitrogen after short oxidation times is modified by LSP treatment.•A mechanism to explain the reduction of oxygen diffusion in LSP treated samples is proposed.