0000000000541801
AUTHOR
Manuel François
Improving the high temperature (HT) oxidation resistance of a Beta-Titanium alloys by mechanical treatments
International audience
Improving the high temperature oxidation resistance of pure titanium by shot-peening treatments
International audience; Shot-peening (SP) treatments have shown their capacity to improve the oxidation resistance of titanium and zirconium thanks to the large compressive stresses and the surface hardening induced by this mechanical process. However, shot-peening treatments can produce a surface chemical deposit, which can modify the high temperature oxidation resistance. Here, we study pure titanium samples shot-peened with different type of balls: tungsten carbide, alumina or glass. The oxidation behavior was studied at 700 °C in dry air by thermo gravimetric analysis for short isotherm oxidation periods up to 100 h. Also, long oxidation tests (3000 h) at 700 °C were performed with an i…
Influence of surface Shock-peening treatment on high temperature oxidation of Titanium
International audience
Improving the high temperature oxidation resistance of Ti-β21S by mechanical surface treatment
The improvement of the high temperature oxidation resistance of titanium alloys is currently a technological challenge. Mechanical surface treatments as shot-peening (SP) have shown their ability to improve the behaviour of pure zirconium and titanium. However, shot-peening treatments can induce a significant surface contamination. Laser shock peening (LSP) appears as a good alternative. Here, we have investigated the effect of SP and LSP treatments on the HT oxidation behavior of Ti-β21S. Samples treated by these methods have been compared to untreated ones for long exposures (3000 h) at 700 °C in dry air. The samples placed in a furnace at 700 °C were periodically extracted to be weighed.…
Nouvelle approche dans l'analyse des contraintes résiduelles par l'interférométrie de Speckle
International audience
Residual strain and stress analysis by speckle interferometry combined with the drill of a groove
A new method for residual stresses determination combining Electronic Speckle Pattern Interferometry (ESPI) with the machining of a groove. The internal stress field is perturbed as the depth of the groove is increased incrementally [1]. The structure finds a new equilibrium state generating displacements which are measured using ESPI. This method was tested on an aluminium alloy plate treated locally by ultrasonic shot-peening. The investigation of the images obtained with the phase shifting technique and fringe patterns makes it possible to analyze, simultaneously, the stress profile along two directions: along the depth of the structure, and along the groove direction.
MICRO-SCALE STUDY OF RESIDUAL STRESSES IN CR2O3 COATINGS SPRAYED BY APS
International audience; Whichever the application field, every material forming process generates residual stresses on the surface. While they are likely to enhance the aimed properties of the final mechanical part, these stresses may also drastically reduce them and result in early failures. Therefore, understanding the residual stress state remains a major challenge when coating complex parts, especially as most characterization methods at the microscopic scale involve specific sample preparation procedures which may affect the residual stresses field. This work investigates the residual stress state that exists in chromium oxide coatings deposited via Atmospheric Plasma Spray (APS), usin…
Retarding the high temperature oxidation of Titanium by shot-peening surface treatment
International audience
Kinetics study of mechanically treated pure titanium with enhancement of the high temperature oxidation resistance
International audience
Role of nitrogen in the high temperature oxidation of mechanically treated pure titanium
International audience