Influence of Incident Angle on Surface Integrities of 7075 Aluminum Alloy Covered With the Flexible Coating Material During Laser Shot Peening

Author:  Qinxiang Xia, Junhao Zhang, Xiuquan Cheng, Xiao Xu
Source:  ICSP-13
Doc ID:  2017114
Year of Publication:  2017
Abstract:  
Introduction: The aircraft parts are susceptible to the corrosion damage due to the fatigue load, slight rubbing and corrosive environment during the long flight service [1]. For some slight damaged aircraft parts, the damaged aircraft parts can continue to be used after removing the corroded portion by grinding and then strengthening the ground area by shot peening [2]. Online repairment refers to the method that repairing the damaged parts without disassembly. Compared with the off-line repairment, online repairment has the advantages of saving repairment time, reducing repairment cost and maintaining the original coordination accuracy of parts. Laser shot peening has a wide application prospect because of its good accessibility [3]. Oblique angle laser shot peening during the online repairment of the damaged aircraft parts has to be adopted due to the limitation of the cabin space,which brings the difficulties of impacting along the normal direction in each impact.Focus on the gas turbine blades strengthening, Suh U W et al.[4] designed a device which realized the simultaneous double side oblique laser shot peening and applied for a patent. But the influence of laser incident angle on the strengthening effect was not studied. Leihong Z et al.[5] studied the influence of laser incident angle on sheet forming based on theoretical derivation and experiments. The results show that with the increasing of laser incident angle, the deformation alone the vertical direction decreases while the deformation alone the horizontal direction increases. But it was not mentioned the laser shot peening strengthening process. The laser incident angle θ is the angle between the axis of laser beam and the normal direction of the target material, which is an index to describe the slope degree of laser oblique impact [6]. Surface integrities refers to the qualities of surface microhardness, surface topography, residual stress, and etc.[7]. The surface microhardness, surface topography and residual stress under the different laser incident angle θ were obtained to investigate the influence of θ on the strengthening effect during laser shot peening for providing the selection guidance of laser incident angle during the actual repairment of the damaged aircraft parts.