The Experts below are selected from a list of 162 Experts worldwide ranked by ideXlab platform
Maria Cristina More Farias - One of the best experts on this subject based on the ideXlab platform.
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high temperature oxidation of sintered austenitic stainless steel containing boron or yttria
Corrosion Science, 2017Co-Authors: M Peruzzo, T D Beux, M F C Ordonez, R M Souza, Maria Cristina More FariasAbstract:Abstract The present study examines the cyclic oxidation behaviour at 900 °C in air of sintered 316L austenitic stainless steels containing 1 wt.% yttria or 0.6 wt.% boron. The microstructures of the sintered and oxidized samples were characterised by field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analyses. The two-dimensional image analyses of the pore amount, size and shape was correlated with the oxidation rate. The oxidation resistance of the sintered materials is influenced not only by the porosity characteristics but also by the capability of the Alloy Element or compound to form a more protective oxide scale. For the conditions chosen in this study, the boron-containing steel was found to provide a strong improvement in the high-temperature cyclic oxidation, which appears to be related to both the high densification favoured by the eutectic reaction and the presence of an iron borate. For the yttria-containing steel, the effect of porosity on oxidation rate was suppressed by the presence of oxides containing yttria and chromium.
J H Feng - One of the best experts on this subject based on the ideXlab platform.
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microstructure mechanical properties and interface bonding mechanism of hot rolled stainless steel clad plates at different rolling reduction ratios
Journal of Alloys and Compounds, 2018Co-Authors: S Wang, C X Chen, J H FengAbstract:Abstract The microstructure, interfacial characteristics, shear behavior, tensile properties and fracture morphologies of stainless steel clad plates fabricated by vacuum hot rolling at different rolling reduction ratios of 20%, 40%, 70%, 90% and 93.75% are investigated using optical microscope (OM), ultra-depth microscope, scanning electron microscope (SEM), electron probe microanalysis (EPMA) and universal testing in detail. With the increasing rolling reduction ratio, the refinement degree of microstructure is increased, while the thicknesses of interface Alloy Element diffusion zones including the decarburized, carburized layers and martensite zone are decreased. Due to the different interface bonding status, the shear fracture of clad plate rolled at a low reduction ratio of 40% is located at interface, while clad plates with high reduction ratios of 70% and 90% fracture at the decarburized layers. Therefore, interface shear strength is sharply and then slightly increased. Moreover, the interface bonding strength, tensile strength and interface deformation coordination are increased, while fracture elongation is increased firstly and then decreased with the increasing rolling reduction ratio, which are attributed to the competing mechanisms of grain refinement, work hardening, interface strengthening and intergranular cracks of carburized layer. Overall, the interfacial bonding mechanism can be related to the Mn-Si oxide inclusions rupture, Alloying Elements diffusion, phase transition and severe plastic deformation at high rolling temperature.
G D W Smith - One of the best experts on this subject based on the ideXlab platform.
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three dimensional atom probe characterization of Alloy Element partitioning in cementite during tempering of Alloy steel
Ultramicroscopy, 2007Co-Authors: Chen Zhu, Xiangyuan Xiong, A Cerezo, R Hardwicke, George Krauss, G D W SmithAbstract:Abstract Hardness measurements confirm that the martensitic microstructure of an Alloy steel, AISI/SAE 4340, is significantly more resistant to softening, compared to the martensitic microstructure of a high-purity Fe–0.4% C Alloy, at tempering temperatures, 300–400 °C, just above the temperatures where cementite replaces transition carbides in the martensitic matrix. Three-dimensional atom probe (3DAP) analyses of the 4340 steel show that Si rejection from the cementite is first detected after low-temperature tempering for times of 1 h. After 10-h tempering at 400 °C, Mn and Cr contents are increased, and Ni contents decreased, in cementite according to their carbide- and non-carbide-forming tendencies, respectively. The results are discussed with respect to the diffusivity of the substitutional Alloying Elements in the 4340 steel, and the effect that such diffusion-controlled redistribution would have on maintaining fine distributions of cementite that resist softening during tempering.
G P Zhang - One of the best experts on this subject based on the ideXlab platform.
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influence of Alloy Element partitioning on strength of primary α phase in ti 6al 4v Alloy
Journal of Materials Science & Technology, 2017Co-Authors: Lilan Zeng, Honglei Chen, L M Lei, G P ZhangAbstract:Abstract The partitioning effect of Al (α-phase stabilizer) and V Elements (β-phase stabilizer) on strength of the primary α phases in the α/β Ti-6Al-4V Alloy with the bimodal microstructure was investigated. It was found that partitioning of Al and V Elements took place in the Ti-6Al-4V Alloy during the recrystallization process, leading to the variation of the content of Al and V Elements in the primary α phases with changing the volume fraction of the primary α phase. Nanoindentation tests reveal a general trend that the strength of the primary α phases increases with decreasing the volume fraction of the primary α phases, and such trend is independent on the loading direction relative to the c-axis of the α phase. The enhanced strength is attributed to the increase of the content of Al Element in the primary α phase, but it is not dominated evidently by the change of the V content. The solid solution strengthening contributed from both the elastic strain introduced by the solute atoms and the variation of the density of states was estimated theoretically.
Honglei Chen - One of the best experts on this subject based on the ideXlab platform.
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influence of Alloy Element partitioning on strength of primary α phase in ti 6al 4v Alloy
Journal of Materials Science & Technology, 2017Co-Authors: Lilan Zeng, Honglei Chen, L M Lei, G P ZhangAbstract:Abstract The partitioning effect of Al (α-phase stabilizer) and V Elements (β-phase stabilizer) on strength of the primary α phases in the α/β Ti-6Al-4V Alloy with the bimodal microstructure was investigated. It was found that partitioning of Al and V Elements took place in the Ti-6Al-4V Alloy during the recrystallization process, leading to the variation of the content of Al and V Elements in the primary α phases with changing the volume fraction of the primary α phase. Nanoindentation tests reveal a general trend that the strength of the primary α phases increases with decreasing the volume fraction of the primary α phases, and such trend is independent on the loading direction relative to the c-axis of the α phase. The enhanced strength is attributed to the increase of the content of Al Element in the primary α phase, but it is not dominated evidently by the change of the V content. The solid solution strengthening contributed from both the elastic strain introduced by the solute atoms and the variation of the density of states was estimated theoretically.