Reza Karimian - Department of Metallurgy and Materials Engineering, Yazd Branch, Islamic Azad University, Yazd,Iran
Mahmoud Hajisafari - Department of Metallurgy and Materials Engineering, Yazd Branch, Islamic Azad University, Yazd,Iran

At the present study, effects of Polishing process after shot peening were investigate on fatigue prope rties of 6063-T5 aluminum alloy. At the beginning, a shot peening process was performed on a group of samples, and then polishing was performed, then fatigue properties of aforementioned samples were studied via standard rotating-bending fatigue test. But the smooth surface after shot peening also one of the important parameters increase or decrease the fatigue life of samples. Results revealed that shot peening process caused a considerable increase on fatigue life of samples in air. Furthermore, the normal polished samples (without shot peened) presented fatigue strength and fatiguelife equal to 80 Mpa and 7×105 cycles, respectively, fatigue limited and fatigue life shot peening samples (without polishing) in order of 80 Mpa and 11×106 cycles, were recorded for shot peened samples respectively at the same conditions. While the fatigue limited and fatigue life for shot peening polishing samples of 80 Mpa and 15×106 cycles respectively. The Microstructural studies showed that the fatigue crack nucleation and propagation of shot peening samples were occurred in internal layer prior to the external surface due to presented residual stress caused by shot particles on the surface and polishing process does not reduce fatigue life in shot peening samples. Also, the propagation processwere stopped by shot peening zone. In addition, there were some obvious deviations in crack propagation route due to facing to the impurities like Mg2Si

Aluminum, Shot Peening, Fatigue Life, Fatigue Strength, Fatigue Limit