Influence of Mechanical Surface Treatment on High-Temperature Oxidation of Pure Titanium

Abstract

International audienceThe excellent combination of light-weight and good mechanical propertiesmakes titanium alloys attractive for compressor section components in gasturbine engines (temperature between 250 and 600 C). However, above 600 C,the formation of an unprotective oxide layer facilitates the oxygen diffusion into thealloy. In this experimental study, pure titanium was treated with mechanical surfacetreatment to promote better protection against oxidation at high temperature. Shotpeenedand laser-shock peened specimens were compared to untreated samples interms of oxidation behavior at high temperature. We used thermal gravimetricanalysis to oxidize the samples at 700 C for 100 h. Subsequently, XRD, opticalmicroscopy, SEM/EDS, NRA, micro-Raman spectroscopy, and micro-hardnesswere used to characterize the oxide scale and the alpha-case layer formed during thehigh-temperature exposure. The shot-peened samples oxidized less (-45%) than theuntreated and laser-shock peened samples. This behavior was attributed to theformation of a continuous nitride layer between oxide and meta

High temperature oxidation resistance and microstructure of laser-shock peened Ti-Beta-21S

“…Those techniques are already used in the industry to improve some particular properties of metals at ambient temperature: mechanical (fatigue resistance) [6,7], tribological (resistance to wear) [8,9] and electrochemical (resistance to pitting) [10]. The beneficial effect of SP and LSP treatments on the high temperature (HT) oxidation resistance of pure titanium at 700°C has been reported by Kanjer et al [11,12]. The reduction of both the mass gain and the diffusion length of oxygen in the Ti-α matrix [12], which corresponds to the so-called α-case, were remarkable in LSP treated samples.…”

Effect of mechanical surface treatments on the high temperature oxidation of pure titanium: the role of nitrogen

“…The cross-sections of the three samples were also analysed by nuclear reaction analysis (NRA) in scanning mode in order to investigate the diffusion of oxygen and also nitrogen in the metal under the oxide layer. The energy of the deuteron beam was fixed at 0.92 MeV, which allows detecting the nuclear reactions of the 16 O isotope (17), but also those of the isotopes 14 N and 12 C. However, the cross-section of the nitrogen nuclear reactions is low within these experimental conditions. Figure 4 shows the NRA maps (300 x 400 μm 2 ) obtained for the isotopes 16 O, 12 C and 14 N in the cross-section of the samples US-3000h, SP-3000h and LSP-3000h.…”

“…NRA maps (300 x 400 μm 2 ) displaying the spatial distribution of the isotopes16 O, 12 C and 14 N in the crosssection of the samples US-3000h, SP-3000h and LSP-3000h.…”

High-Temperature Oxidation Behavior of Ti6242S Ti-based Alloy

“…This large surface area can be reduced through grinding, as shown by Casadebaigt et al who oxidized TA6V (Ti-6Al-4V) alloys obtained by laser and electron beam melting in the 500-600 °C temperature range [7]. Shotpeening was also used by various researchers to improve the properties of commercially pure Ti [8][9][10] and Ti-based alloys [11,12]. After oxidation for only 1 h at 700 °C, Wen et al noticed a slight increase in O, N and C contents in the near surface of commercially pure Ti after shot-peening followed by light grinding (aimed at removing 3-6 µm) [8].…”