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Dai F.Z.,Jiangsu University | Dai F.Z.,Jiangsu Key Laboratory of Photon manufacturing science and technology | Wen D.P.,Jiangsu University | Wen D.P.,Jiangsu Key Laboratory of Photon manufacturing science and technology | And 7 more authors.
Materials and Design | Year: 2015

A method called masked laser ablation (MLA) was proposed to fabricate a micro-dimple array on a substrate surface with a pulsed Nd:YAG laser. Micro-dimple arrays were successfully fabricated on the surface of Ti6Al4V samples both in air and water. The aim of this paper was to investigate the influence of processing parameters on the morphology of micro-dimples, spatter deposition, micro-dimple depth and ablation rate. Contrast experiments were conducted to evaluate the effects of masks. Results showed that the shape of micro-dimples in air could be affected by the overlapping of spatter between the adjacent micro-dimples, while in water it is nearly copied from the mask. The bottom of the micro-dimple fabricated in water was coarse but the periphery was clean. The spatter deposition extremely depended on the laser intensity, pulse numbers and surroundings. Discussions about the existence of masks were carried on. © 2015. Source


Dai F.Z.,Jiangsu University | Dai F.Z.,Jiangsu Key Laboratory of Photon manufacturing science and technology | Lu J.Z.,Jiangsu University | Lu J.Z.,Jiangsu Key Laboratory of Photon manufacturing science and technology | And 7 more authors.
Vacuum | Year: 2014

In this paper, a novel micro-dent array fabrication technique called net mask laser shock processing (NMLSP) was proposed. Micro-dent arrays were successfully fabricated on the surface of ANSI 304 stainless steel. The research goals of this paper are to find out the influence of processing parameters on the surface topography, microhardness and residual stress distribution of treated samples. A new method was proposed to measure the microhardness of unregularly curved surface. This method can be adapted to measure any type of surface with high precision. Results showed that the surface topography and the microhardness-distribution were different from previous studies. These were because the interference of neighboring surface shock waves. Compressive residual stress was found on the curved surface although the treated region was masked. However, it did not be saturated as regular laser shock processing (LSP) treatment after five NMLSP impacts. © 2014 Elsevier Ltd. All rights reserved. Source


Dai F.Z.,Jiangsu University | Dai F.Z.,Jiangsu Key Laboratory of Photon manufacturing science and technology | Zhang Y.K.,Nanjing Southeast University | Lu J.Z.,Jiangsu University | And 8 more authors.
Surface and Coatings Technology | Year: 2015

A method called rigid contact laser shock processing (RCLSP) technique was presented in this paper. LY2 aluminum alloy samples with different initial surface topographies were treated by RCLSP with different technological parameters, and then surface topographies were carefully investigated with a non-contact optical profiler (NCOP) before and after RCLSP. Results showed that whatever the initial surface topography, there was a final value about surface roughness. Compared with the regular LSP technique, the RCLSP technique could effectively reduce the surface roughness. © 2014 Elsevier B.V. Source


Dai F.,Jiangsu University | Dai F.,Jiangsu Key Laboratory of Photon manufacturing science and technology | Zhou J.,Jiangsu University | Zhou J.,Jiangsu Key Laboratory of Photon manufacturing science and technology | And 4 more authors.
Applied Surface Science | Year: 2016

A technique called elastic contact laser shock peening (ECLSP) is presented in this paper. In this technique, a metal foil with high dynamic yield strength is fixed between absorbing layer and workpiece, and the peak pressure of laser shock wave is a little less than the dynamic yield strength of metal foil, but higher than the Hugoniot Elastic Limit (HEL) of work piece. Surface roughness, microhardness and residual stress are investigated. Compared with regular laser shock peening (LSP), ECLSP can reduce the depth and area of secondary plastic deformation of overlapping region. This can effectively reduce surface roughness in overlapping LSP. Measurement of microhardness and residual stress shows that the work hardening effects and strengthening effect are similar as regular LSP. © 2016 Elsevier B.V. All rights reserved. Source

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