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

Abstract

a b s t r a c tThe 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 (10 h and 100 h) 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, microRaman 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 graintexture of LSP samples after oxidation can also explain the improvement of the high temperature oxidation resistance after long times exposures.

Improving the high temperature oxidation resistance of Ti-β21S by mechanical surface treatment

“…As it was reported in previous works [11,12], in the case of commercially pure Ti-a untreated and SP treated samples studied in the same conditions showed spallation of the oxide layer after about 1700 h at 7000 °C. On the contrary, LSP treated Ti-a showed a homogeneous oxide layer, and a mass gain of 6.7 mg/cm 2 after 3000 h.…”

“…Recent works by Raceanu et al [9] show a positive role of the mechanical treatments in the oxidation resistance of zirconium due to the large compressive stresses induced by the treatment underneath the surface. More recently, Kanjer et al reported the beneficial effect of mechanical treatments on the oxidation resistance of pure titanium at high temperature in air [10][11][12].…”

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

“…Previous studies showed that the SP treatment induces contamination with WC particles coming from the shotpeening balls (14), whereas the LSP treatment preserves the surface chemically clean (15). Figure 2 shows the mass gain for long oxidation tests, up to 3000 hours.…”

“…Two kinds of mechanical treatments were used in this work: ultrasonic shot-peening (SP) and laser-shock peening (LSP). Experimental details on both kinds of treatments are given in previous papers (14) (15). For simplicity, shot-peened samples are named here SP, while laser-shock peened samples are named LSP in the following sections.…”

The Cyclic Oxidation and Hardness Characteristics of Thermally Exposed Titanium Prepared by Inductive Sintering-Assisted Powder Metallurgy

“…Meanwhile, only a few reports have been found on the oxidation behavior of Ti at temperatures of 700 • C and 800 • C [ [14][15][16]. There has been limited attention on the cyclic oxidation and hardness characteristics of thermally exposed Ti at elevated temperatures prepared by the inductive sintering method.…”