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Morphology transformation of primary strip α phase in hot working of two-phase titanium alloy 被引量:4
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作者 xiao-guang fan He YANG +3 位作者 Peng-fei GAO Rui ZUO Peng-hui LEI Zhe JI 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第6期1294-1305,共12页
Microstructural development in hot working of TA15titanium alloy with primary stripαstructure was investigated withthe aim to globularizeαstrips.Results show that the mechanisms of morphology transformation are the ... Microstructural development in hot working of TA15titanium alloy with primary stripαstructure was investigated withthe aim to globularizeαstrips.Results show that the mechanisms of morphology transformation are the same to the spheroidizationmechanisms of lamellar structure.Boundary splitting and termination migration are more important than coarsening due to the largesize of stripα.Theαstrips are stable in annealing due to the unfavorable geometrical orientation of intra-αboundaries,the largethickness of strip and the geometrical stability ofαparticles.Predeformation and low speed deformation accelerate globularization ofαstrips in the following ways:direct changing of particle shape,promotion of boundary splitting and termination migration byincreasing high angle grain boundaries and interfacial area,promotion of coarsening by forming dislocation structures.Largepredeformation combined with high temperature annealing is a feasible way to globularize stripα. 展开更多
关键词 titanium alloy primary α strips globularization morphology transformation hot working COARSENING
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Prediction of tri-modal microstructure under complex thermomechanical processing history in isothermal local loading forming of titanium alloy 被引量:5
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作者 Peng-fei GAO He YANG +2 位作者 xiao-guang fan Zhen-ni LEI Yang CAI 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第11期2423-2433,共11页
To control the tri-modal microstructure and performance,a prediction model of tri-modal microstructure in the isothermal local loading forming of titanium alloy was developed.The staged isothermal local loading experi... To control the tri-modal microstructure and performance,a prediction model of tri-modal microstructure in the isothermal local loading forming of titanium alloy was developed.The staged isothermal local loading experiment on TA15alloy indicates that there exist four important microstructure evolution phenomena in the development of tri-modal microstructure,i.e.,the generation of lamellarα,content variation of equiaxedα,spatial orientation change of lamellarαand globularization of lamellarα.Considering the laws of these microstructure phenomena,the microstructure model was established to correlate the parameters of tri-modal microstructure and processing conditions.Then,the developed microstructure model was integrated with finite element(FE)model to predict the tri-modal microstructure in the isothermal local loading forming.Its reliability and accuracy were verified by the microstructure observation at different locations of sample.Good agreements between the predicted and experimental results suggest that the developed microstructure model and its combination with FE model are effective in the prediction of tri-modal microstructure in the isothermal local loading forming of TA15alloy. 展开更多
关键词 titanium alloy isothermal local loading forming complex thermomechanical processing history tri-modal microstructure modelling
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Deformation banding in β working of two-phase TA15 titanium alloy 被引量:3
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作者 xiao-guang fan Xiang ZENG +4 位作者 He YANG Peng-fei GAO Miao MENG Rui ZUO Peng-hui LEI 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第11期2390-2399,共10页
To study deformation banding inβworking of TA15titanium alloy,hot simulation compression experiments were carried out on a Gleeble3500thermal simulator,and the microstructure was investigated by optical microscopy(OM... To study deformation banding inβworking of TA15titanium alloy,hot simulation compression experiments were carried out on a Gleeble3500thermal simulator,and the microstructure was investigated by optical microscopy(OM)and electron backscattered diffraction(EBSD).It is found that inβworking of TA15titanium alloy,deformation banding is still an important grain refinement mechanism up to temperature as high as0.7Tm(Tm is the melting temperature).Boundaries of deformation bands(DBBs)may be sharp or diffusive.Sharp DBBs retard discontinuous dynamic recrystallization(DDRX)by prohibiting nucleation,while the diffusive ones are sources of continuous dynamic recrystallization(CDRX).Deformation banding is more significant at high strain rate and large initial grain size.The average width of grain subdivisions is sensitive to strain rate but less affected by temperature and initial grain size.Multi-directional forging which produces crossing DDBs is potential to refine microstructure of small-size forgings. 展开更多
关键词 TA15 titanium alloy β working deformation banding grain refinement dynamic recrystallization
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Direct preparation of semi-solid billets by the semi-solid isothermal heat treatment for commercial cold-rolled ZL104 aluminum alloy
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作者 Yong-fei Wang Yi Guo +1 位作者 Sheng-dun Zhao xiao-guang fan 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2021年第7期1164-1173,共10页
Semi-solid isothermal heat treatment was proposed to directly process cold-rolled ZL104 aluminum alloys and obtain semi-solid bil-lets.The effects of two process parameters,namely,temperature and processing time,on th... Semi-solid isothermal heat treatment was proposed to directly process cold-rolled ZL104 aluminum alloys and obtain semi-solid bil-lets.The effects of two process parameters,namely,temperature and processing time,on the microstructure and hardness of the resulting bil-lets were also experimentally examined.Average grain size(AGS)increased and the shape factor(SF)of the grain improved as the process temperature increased.The SF of the grain also increased with increasing processing time,and the AGS was augmented when the processing time was prolonged from 5 to 20 min at 570℃.The hardness of the aluminum alloy decreased because of the increase in AGS with increasing temperature and processing time.The optimal temperature and time for the preparation of semi-solid ZL104 aluminum alloys were 570℃and 5 min,respectively.Under optimal process parameters,the AGS,SF,and hardness of the resulting alloy were 35.88μm,0.81,and 55.24 MPa,respectively.The Lifshitz-Slyozov-Wagner relationship was analyzed to determine the coarsening rate constant at 570℃,and a rate constant of 1357.2μm3/s was obtained. 展开更多
关键词 SEMI-SOLID aluminum alloy MICROSTRUCTURE HARDNESS semi-solid isothermal heat treatment
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Phase fraction evolution in hot working of a two-phase titanium alloy: experiment and modeling 被引量:1
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作者 xiao-guang fan Huo-Jun Zheng +2 位作者 Peng-Fei Gao Mei Zhan Wen-Jia Mei 《Rare Metals》 SCIE EI CAS CSCD 2017年第10期769-779,共11页
In the present work, the coupled effects of initial structure and processing parameters on microstructure of a two-phase titanium alloy were investigated to predict the microstructural evolution in multiple hot workin... In the present work, the coupled effects of initial structure and processing parameters on microstructure of a two-phase titanium alloy were investigated to predict the microstructural evolution in multiple hot working. It is found that microstructure with different constituent phases can be obtained by regulating the initial structure and hot working conditions. The variation of deformation degree and cooling rate can change the morphology of the con- stituent phases, but do not alter the phase fraction. The phase transformation during heating and holding determi- nes the phase fraction for a certain initial structure. ^--at-~3 transformation occurs during heating and holding. [3 to ct transformation leads to a significant increase in content and size of lamellar ~. The ct to [3 transformation occurs simultaneously in equiaxed at and lamellar ct. The thickness of lamellar ~t increases with temperature, which is caused by the vanishing of fine a lamellae due to phase transformation and coarsening by termination migration. By assuming a quasi-equilibrium phase transformation in heating and holding, a modeling approach is proposed for predicting microstructural evolution. The three stages of phase transformation are modeled separately and combined to predict the variation of phase fraction with temperature. Model predictions agree well with the experimental results. 展开更多
关键词 Titanium alloy Hot working MICROSTRUCTURE MODELING
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Quantitative analysis of microstructure evolution induced by temperature rise during(α+β) deformation of TA15 titanium alloy 被引量:2
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作者 Liang-Gang Guo Shuai Zhu +2 位作者 He Yang xiao-guang fan Fu-Long Chen 《Rare Metals》 SCIE EI CAS CSCD 2016年第3期223-229,共7页
Temperature rise is a significant factor influencing microstructure during(α+β) deformation of TA15 titanium alloy.An experiment was designed to explore microstructure evolution induced by temperature rise due to... Temperature rise is a significant factor influencing microstructure during(α+β) deformation of TA15 titanium alloy.An experiment was designed to explore microstructure evolution induced by temperature rise due to deformation heat.The experiment was carried out in(α+β) phase field at typical temperature rise rates.The microstructures of the alloy under different temperature rise rates were observed by scanning electron microscopy(SEM).It is found that the dissolution rate of primary equiaxed a phase increases with the increase in both temperature and temperature rise rate.In the same temperature range,the higher the temperature rise rate is,the larger the final content and grain size of primary equiaxed a phase are due to less dissolution time.To quantitatively depict the evolution behavior of primary equiaxed a phase under any temperature rise rates,the dissolution kinetics of primary equiaxed a phase were well described by a diffusion model.The model predictions,including content and grain size of primary equiaxed a phase,are in good agreement with experimental observations.The work provides an important basis for the prediction and control of microstructure during hot working of titanium alloy. 展开更多
关键词 TA15 titanium alloy Temperature rise Deformation heat Microstructure evolution model
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