Papers by Author: Hong Liang Hou

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Authors: Qi Jin, Xue Ping Ren, Hong Liang Hou, Yan Ling Zhang, Hai Tao Qu
Abstract: In this paper, the metal/ceramic functionally graded composites are prepared. The thermal stress of TiC/Ti functionally graded composites are simulated by Abaqus finite element analysis software to study the influence of the number of layers, the gradient layer thickness and the gradient of distribution index.The optimal structural parameters of the TiC/Ti functional gradient composites are obtained as the number of layers of 6 and the gradient distribution index 0.8. According to the optimized structural parameters, Ti and C powders are mixed by high-energy ball milling, then the TiC/Ti functional gradient composites are prepared by spark plasma sintering. The gradient distribution of composition and microstructure in TiC/Ti functionally graded composites are achieved, which can solve the problem of mismatch for the physical properties between the metal and the ceramic in the composite material.
Authors: Xiao Li Wang, Yong Qing Zhao, Hong Liang Hou, Wei Dong Zeng
Abstract: The superplastic forming and diffusion bonding (SPF/DB) of hydrogenated Ti-6Al-2.8Sn-4Zr-0.5Mo-0.4Si-0.1Y (Ti600) alloys were carried out in the temperature range of 1073-1213K under 1.5MPa gas pressure. The effects of hydrogen contents and diffusion temperature on welding-on ratio of SPF/DB and microstructure of interface and matrix in Ti600 alloy were investigated by OM and SEM. According to the experimental investigation, when the parameters of SPF/DB were as follows: T=860°C, P=1.5MPa and t=70min, the welding-on ratio of Ti600 alloy with hydrogen 0.5wt% was 100 percent. However, the physical contact of Ti600 alloy without hydrogen which was related to plastic forming could not occur. Moreover, the size and amount of voids at the diffusion bonding interface decreased and diffusion bonding quality improved gradually with the increase of hydrogen content and diffusion temperature, which was attributed to the decrease of phase transformation temperature and flow stress of plastic forming as well as the release of hydrogen. After SPF/DB, the recrystallization of joint grains through the interface was formed, and the matrix of hydrogenated Ti600 alloy changed.
Authors: J.W. Zhao, Hua Ding, Wen Juan Zhao, X.F. Tian, H.W. Xiao, Hong Liang Hou
Abstract: The microstructures of Ti6Al4V alloy after hydrogenation have been investigated and analysed by optical microscopy (OM), X-ray diffraction (XRD) and transmission electron microscopy (TEM), and the influence of hydrogenation on the hardness of α and β phases has been analysed by microhardness testing. The microstructure observation revealed that δ hydride (fcc structure) precipitated in the specimens with 0.278 wt.% and 0.514 wt.% hydrogen, and a lot of dislocations and twins have been found simultaneously. The diffraction peaks moved to the lower angles because of the lattice expansion of β phase with the solution of hydrogen atoms. The result of microhardness testing shows that the hardness of α and β phases increases synchronously with increasing of hydrogen and the increment of β is larger than that of α. It is considered that the formation of δ hydrides, lattice defects and alloying element diffusion are the major factors leading to the microhardness change.
Authors: Peng Tao Liu, Xiu Juan Zhao, Tian Cang Zhang, Hong Liang Hou, Chun Huan Chen, Rui Ming Ren
Abstract: The linear friction welding (LFW) performance of hydrogenated Ti-6Al-4V alloy was investigated. The effects of hydrogen on macro-features and axial shortening as well as microstructure of Ti-6Al-4V alloy joints welded by LFW were analyzed. The mechanical properties of joints after dehydrogenation were also examined by tensile test at room temperature. The results indicated that the hydrogenated Ti-6Al-4V specimens containing 0.3~0.4 wt% hydrogen had a better microstructure and plastic deformation ability, which resulted in the optimum welding performance improvement of LFW. The critical power input of LFW could be lowered by addition of hydrogen to Ti-6Al-4V alloy. The results of tensile test showed that joints which experienced thermohydrogen processing possessed the same tensile strength and plasticity as original joints.
Authors: Zhi Qiang Li, Hong Liang Hou, Y.Q. Wang
Abstract: Effects of hydrogen on superplastic deformation behavior were investigated through high temperature tensile experiment in this paper. It is found that reasonable hydrogen contents can improve the superplastic behavior such as lowering flow stress and temperature and increasing m value. While addition of 0.1wt% hydrogen in Ti-6Al-4V alloy, peak flow stress decrease to 53%, deformation temperature decrease 60°C. The influence of hydrogen on microstructure transition by means of optic microscope, SEM, TEM and XRD was also researched. The results show that β phase amounts in the hydrogenated alloy increase with hydrogen contents, while hydrogen contents reach to 0.2wt%, martensite becoming coarser with the increase of hydrogen contents. Moreover, dislocations density of hydrogenated alloy after deformation is lower than that of unhydrogenated alloy because of hydrogen action.
Authors: Xiao Hui Chen, Chun Xian Jiang, Xue Ping Ren, Hong Liang Hou, He Jun Li
Abstract: The super plastic diffusion bonding behavior of 00Cr25Ni7Mo3N duplex stainless steel was performed on Gleeble-1500 hot simulator. The microstructure of the bonding interface region was studied by using optical microscope (OM), scanning electron microscope (SEM). The mechanical property of the joint was characterized by tensile strength tests. The results indicate that the strength of joint was improved with the increase of the bonding temperature, the applied pressure and the hold time. The suitable bonding temperature is higher about 100°C than its super plastic temperature. The initial bonding boundary were disappeared and the voids were closed by hot plastic deformation under the bonding condition like T=1323K, P=20MPa, t=12min. At the same condition, the grain grew up across the interface by atomic diffusion and the interfacial migration, and the strength of joints was high as 440MPa.
Authors: Wen Juan Zhao, Hua Ding, D. Song, F.R. Cao, Hong Liang Hou
Abstract: In this study, superplastic tensile tests were carried out for Ti-6Al-4V alloy using different initial grain sizes (2.6 μm, 6.5μm and 16.2 μm) at a temperature of 920°C with an initial strain rate of 1×10-3 s-1. To get an insight into the effect of grain size on the superplastic deformation mechanisms, the microstructures of deformed alloy were investigated by using an optical microscope and transmission electron microscope (TEM). The results indicate that there is dramatic difference in the superplastic deformation mode of fine and coarse grained Ti-6Al-4V alloy. Meanwhile, grain growth induced by superplastic deformation has also been clearly observed during deformation process, and the grain growth model including the static and strain induced part during superplastic deformation was utilized to analyze the data of Ti-6Al-4V alloy.
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