Papers by Author: Jun Peng

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Authors: Xiao Li Wang, Bo Song, Yang Bing Li, Sheng Li An, Jun Peng, Guo Ping Fu
Abstract: The corrosion of heavy rail steel is severity in south. Now there are not studies on the corrosion of heavy rail steel in atmosphere. The corrosion of heavy rail steel were studied by periodic infiltration corrosion test and electro-chemical testing technique in simulated industrial atmosphere. The result showed that U76CrRE has apparently more excellent anti-corrosion ability than that of steel U75V. The Cr and Re in U76CrRE enriched in local of base that promotes the rapid generation of α FeOOH and the increase of content. Thus the ability of the rust layer against the corrosive media from entering the layer was improved. Anti-corrosion capacity of heavy railroad steel in industrial atmosphere can be improved significantly by adding Cr and RE alloy.
Authors: Jun Peng, Vincent Ji, Jian Min Zhang, Wilfrid Seiler
Abstract: The non-destructive analysis by GIXRD allows us to determine the residual stress distribution as a function of XRD penetration depth and film thickness. A new development on the determination of residual stresses distribution is presented here. The procedure, based on the GIXRD geometry (referred to here as the ‘sin2ψ*’), enables non-destructive measurement of stresses gradient with only one diffraction family plan at a chosen depth taking into account the correction of measured direction. The chosen penetration depth is well defined for different combination of ψ and Φ and needs not to be changed during experimentation. This method was applied for measurement of residual stress gradient in Cu thin films. The obtained residual stress levels and their distribution were quite comparable with those determined by another multi-reflection method.
Authors: Jun Peng, Vincent Ji, Wilfrid Seiler
Abstract: Residual stresses levels and their distributions in thin films have an important effect on their mechanical properties. The non-destructive analysis by pseudo-grazing incidence X-ray diffraction (GIXRD) allows us to define residual stresses gradients as a function of thin film depth. In case of pseudo-GXRD, we must take into account the effects due to surface roughness on residual stress analysis. We have investigated firstly a set of carbon steel specimens with different surface roughness (RZ varies from 4.2µm to 9.5µm) obtained by grinding. All specimens were tempered to eliminate the residual stresses due to machining. With K radiation of Chromium, Bragg peak positions were determined with various incidence angles  (varies from 1° to 78°) for each specimen. Secondly, a carbon steel specimen containing 4 zones with different surface roughness was loaded elastically in tension, pseudo-GIXRD has used for stress analysis on the loaded specimen with various incidence angles. The peak shifts due to the surface roughness were studied as function of different roughness and different incidence angles. The stress relaxation due to surface roughness was then studied.
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