Abstract
Laser shock peening has established itself as an effective surface treatment to enhance the fatigue properties of metallic materials. Although a number of works have dealt with the formation of residual stresses, and their consequent effects on the fatigue behavior, the influence of material geometry on the peening process has not been widely addressed. In this paper, Laser Peening without Coating (LPwC) is applied at the surface of a notch in specimens made of a 6082-T6 aluminum alloy. The treated specimens are tested by three-point bending fatigue tests, and their fatigue life is compared to that of untreated samples with an identical geometry. The fatigue life of the treated specimens is found to be 1.7 to 3.3 times longer. Brinell hardness measurements evidence an increase in the surface hardness of about 50%, following the treatment. The material response to peening is modelled by a finite element model, and the compressive residual stresses are computed accordingly. Stresses as high as −210 MPa are present at the notch. The ratio between the notch curvature and the laser spot radius is proposed as a parameter to evaluate the influence of the notch.
Highlights
Laser Shock Peening (LSP) is a technology that makes use of shock waves induced by a laser to improve the mechanical properties of a metallic component
The outcomes of this work, focusing on Laser Peening without Coating (LPwC) applied at a notch, could be of interest for those applications in which the structural integrity is severely affected by the presence of holes and notches, such as aircraft components
The fatigue life of the peened samples shows an improvement over that of the untreated ones, suggesting that laser peening without coating could enhance the fatigue behavior of notched components, to conventional laser shock peening
Summary
Laser Shock Peening (LSP) is a technology that makes use of shock waves induced by a laser to improve the mechanical properties of a metallic component. Fabbro et al [2] studied the use of a transparent overlay as an effective method to confine the generated plasma. This results in the formation of intense shock waves, which induce high residual stresses in the surrounding material, as shown by Sano et al [3]. Conventional laser peening usually employs an ablative layer (i.e., a coating applied on the surface of the material) to prevent damage to the metal surface.
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