Papers by Author: Ru Lin Peng

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Authors: Yan Dong Wang, Ru Lin Peng, Jonathan Almer, Magnus Odén, Y.D. Liu, Liang Zuo
Abstract: Quantitative interpretations of the so-called non-linear lattice strain distributions observed in coatings and thin films are important not only for determining the macro- and microstress fields, but also for inferring the active mechanisms of grain interactions during various deposition processes. In this paper, we present a method, which determines simultaneously both the macro- and micro- stress fields in the coatings and thin films. This method is extended from the previous stress-orientation distribution function (SODF) analysis method, which has already been used for residual stress analysis in bulk materials subjected to rolling and fatigue deformation. The validity of analysis method is demonstrated through measurements of lattice strains by high-energy x-ray and analysis of grain-orientation-dependent stresses in a CrN coating.
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Authors: R. Fernández, Giovanni Bruno, Ru Lin Peng, G. González-Doncel
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Authors: T. Liu, Yan Dong Wang, Shi Ding Wu, Shou Xin Li, Ru Lin Peng, Yong Bo Xu
Abstract: The room temperature tensile strength and ductility of Mg-3.3%Li alloy were improved simultaneously by two kinds of different equal channel angular pressing (ECAP) treatments. Microstructural analyses showed that grain refinement and texture modification are the principal reasons for the improvement of mechanical properties.
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Authors: Ru Lin Peng, J. Gibmeier, Sebastian Eulert, Sten Johansson, Guo Cai Chai
Abstract: The deformation behaviour of the super duplex stainless steel SAF2507 (UNS S32750) under successive uniaxial tensile loading-unloading was investigated with respect to load sharing and inter-phase interactions. The steel consists of 58% austenite and 42% ferrite in volume. By insitu X-ray diffraction experiment the evolution of phase-specific stresses with applied load was monitored for three successive loading-unloading cycles with the maximum total strains being 0.34%, 0.75% and 1.63%, respectively. It was found that yielding occurred earlier in the austenitic phase than in the ferritic phase during the first loading cycle. In the followed loading cycles, both phases yielded under larger but similar applied stresses. Due to a similar behavior of the phases in the elasto-plastic regime inter-phase interactions were relatively weak. Low microstresses induced by the plastic straining resulted in somewhat larger stresses in the ferritic phase.
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Authors: Ru Lin Peng, Yan Dong Wang, Guo Cai Chai, Nan Jia, Sten Johansson, Gang Wang
Abstract: Microstresses due to intergranular and inter-phase interactions in an austenitic-ferritic super duplex steel (SAF 2507) under uniaxial compressive deformation have been studied by in-situ neutron diffraction experiments. Lattice strains of several hkl planes of austenite respective ferrite were mapped as a function of sample direction at a number of load levels during loading into the plastic regime and unloading. The analysis of the experimental results has shown that during loading both grain-orientation-dependent and inter-phase stresses were generated under plastic deformation that was inhomogeneous at the microstructural level. Residual stresses depending on the grain-orientation and phase have been found after unloading. The results also indicate stronger intergranular interactions among the studied hkl planes of austenite than those of ferrite.
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Authors: Ru Lin Peng, Yan Dong Wang, Magnus Odén, Jonathan Almer
Abstract: In this paper, we report on residual stress analysis in physical vapour deposited (PVD) CrN coatings. Two 9 µm thick coatings were grown on tool steel substrates with bias voltages of - 50 V and -300 V, respectively. High-energy (E=80 keV) synchrotron radiation measurements have been performed to investigate residual stresses in both as-deposited and annealed CrN coatings. To understand the origins of non-linear distribution of lattice strain versus sin2ψ for certain (hkl) planes in both coatings, a stress orientation distribution function (SODF) analysis has been carried out, which yields grain-orientation-dependent residual stresses. The results are compared to previous analyses using Reuss and Vook-Witt models on the as-deposited coatings.
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Authors: Christian Schlauer, Ru Lin Peng, Magnus Odén
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Authors: Ru Lin Peng, Sten Å.H. Johansson, Torsten Ericsson, Lena Thorsson
Abstract: In this paper we report our attempts to use the neutron and X-ray diffraction techniques to characterize residual stresses in specimens manufactured by laser FreeForm technique. The aim of our work has been to understand how residua stresses develop during forming and their possible correlation with the microstructure, in particular the pore density which varies with the laser scan speed. The specimens under investigation were built by layer-sintering a ferritic-steel powder with a Cu-based-alloy powder as the binder material. Limited results have been obtained for the ferrite steel phase and are presented in the paper.
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Authors: Yan Dong Wang, Ru Lin Peng, X.H. Zeng, R. McGreevy
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Authors: J.N. Deng, Emmanuel Bouzy, Jean-Jacques Fundenberger, Ru Lin Peng, Chang Shu He, D.Z. Zhang, Yan Dong Wang
Abstract: We find that a severely rolled FeCo alloy has anomalous enhancement of the rotated-cube {100}<011> texture component and a decrease of the {111} components after annealing, which is contrast to the recrystallization behaviors reported in traditional BCC metals and alloys. The local texture measurements show that two kinds of grains with obviously different orientations, i.e. {100} and {111}, are heterogeneously distributed in the deformed specimen and the migration of high-angle grain boundaries is observed after annealing in the disordering temperature region.
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