Abstract
Compared with the laser shock peening, the warm laser shock peening has been demonstrated to get a stable compressive stress distribution under heating and cyclic loading, which is mainly due to warm laser shock peening combined with the advantages of laser shock peening and dynamic strain aging. The surface morphology evaluation of warm laser shock peening was investigated systematically in this work, the GH4169 nickel-base super-alloy is selected as the material with which to conduct experiments of laser shock peening and warm laser shock peening. It can be found that there are a lot of surface ripples appearing after the treatment of warm laser shock peening, which is different from the surface reliefs by the treatment of laser shock peening. Under high temperature and strain rate, δ phase transformed into γ″ phase. Simultaneously, compared with the δ phase of the larger grain size, the grain size of γ″ phase is much smaller, and is unable to form the surface relief. Warm laser shock peening produced a higher dislocation density and more stabilized dislocations that are pinned by the “Cottrell Clouds” formed by γ″ phase, which can inhibit the residual stress failure at the high temperature-alternating load.
Highlights
With the rapid development of the photo-acoustic/photomechanics department, the thermal and mechanical effects of lasermaterial interaction have been widely used in surface strengthening of metallic materials
Warm laser shock peening (WLSP) is an effective surface treatment method to improve the stability of micro-structure and residual stress of metallic materials at high temperature, which takes the advantages of both Laser shock peening (LSP) and dynamic strain aging (DSA).11–13
In combination with the observations, it can concluded that the formation and disappearance of surface ripples morphology are relevant with the presence of the strengthening carbide phase (δ, γ, γ′′, γ′) in GH4169 alloy and the dynamic strain aging of the alloy scitation.org/journal/adv at a higher temperature
Summary
With the rapid development of the photo-acoustic/photomechanics department, the thermal and mechanical effects of lasermaterial interaction have been widely used in surface strengthening of metallic materials. Laser shock peening (LSP) is a novel surface modification technique which can improve the fatigue performance and mechanical properties of alloys and metallic materials by using strong laser-induced plasma shock waves.. Due to strengthening effect such as the high density dislocation, dislocation pinning and grain refinement, etc. The circulation stability and thermal stability of the microstructure can be can improved, and the residual compressive stress relaxation at high temperature or under cyclic loading can be reduced.. Warm laser shock peening (WLSP) is an effective surface treatment method to improve the stability of micro-structure and residual stress of metallic materials at high temperature, which takes the advantages of both LSP and DSA.. The surface morphology is a critical parameter when fatigue strength resistance is concerned, which plays the key role in improving material’s mechanical properties using WLSP. 0.56 nuclear energy and petroleum industry due to excellent fatigue resistance, radiation resistance, corrosion resistance, good machinability and welding performance. In this work, GH4169 is selected as the experiment material, which was based on the experiments of LSP & WLSP. 3D surface microscopic topographies of GH4169 subjected to LSP & WLSP were analyzed systematically
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