Experimental Study on Surface Integrity and Fatigue Performance of Dissimilar Material Stack-Structured Holes Manufactured by Different Processing Method
DONG Zhipeng1 , WANG Yanli1 , YAO Liangliang2 , YANG Fan3 , LIU Wei1
( 1. PLA 32256 Units, Nanning 530000, China; 2. The First Military Representative Office of the Military Equipment Department of the Army in Chongqing Region in Kunming, Kunming 650021, China; 3. Non-Commissioned Officer School of Army Academy of Armored Forces, Changchun 130000, China)
Abstract：In order to study the effect of the dissimilar material stack-structure on the surface integrity and fatigue properties of holes, under the stacked condition, ϕ8.36mm holes were prepared by different processes, such as drilling & reaming, burnishing, and split sleeve cold expansion (SSCX). The surface morphology, surface roughness, residual stress and microstructure were investigated. Fatigue test and fracture surface analysis were performed. The results show that burnishing forms obvious material pile-up at the end of the interlayer hole and introduces circle-shaped micro-crack around the 7B04–T6 hole, while SSCX imparts micro-crack in the region corresponding to sleeve split. Under fatigue loading conditions in present paper, burnishing increases the fatigue life (99.9% survival rate, 95% confidence) of 7B04–T6 and TA15 hole structures by 0.01 times and 0.63 times, and SSCX with interference value of A increases that of 7B04–T6 hole by 3.25 times but reduces that of TA15 holes, while SSCX with interference value of B increases that of 7B04–T6 and TA15 by 18 times and 3.30 times, respectively. The fatigue sources of the three types of hole all originate from the hole wall or corner, and never start from the micro cracks of cold expansion or burnishing
2020, 
