Effects of Ultrafine Particle Peening on Fatigue Properties of ASTM 5056 Aluminum Alloy

Author:  S. Kikuchi, Y. Nakamura, K. Nambu and M. Ando
Source:  Conf Proc 2014: ICSP-12 Goslar, Germany (pgs.136-141)
Doc ID:  2014064
Year of Publication:  2014
Abstract:  
Ultrafine particle peening (Ultra-FPP) using particles (10 μm diameter) was introduced to improve the fatigue properties of ASTM 5056 aluminum alloy. Surface microstructures of the peened specimens were characterized using a micro-Vickers hardness tester, scanning electron microscope (SEM) and X-ray diffraction (XRD) to clarify the fatigue fracture mechanism. The surface hardness of the peened specimen was increased with decreasing peening time. Furthermore, the Ultra-FPP treated specimen had higher hardness than the one treated with conventional FPP using particles (50 μm diameter). Fatigue tests were performed at room temperature using cantilever-type rotating bending fatigue testing machine. It was found that the fatigue life of the Ultra-FPP treated specimen was increased with decreasing peening time due to increasing surface hardness. Especially, Ultra-FPP improved fatigue properties of aluminum alloy in the very high cycle regime for more than 10⁷ cycles. Moreover, numerical calculation of particles velocity was conducted to examine the influence of shot particle size on the microstructural change of aluminum alloy.