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Jiao Luo - One of the best experts on this subject based on the ideXlab platform.

  • Evolution mechanisms of recrystallized grains and twins during Isothermal Compression and subsequent solution treatment of GH4586 superalloy
    Journal of Alloys and Compounds, 2021
    Co-Authors: Jin Yang, Jiao Luo
    Abstract:

    Abstract In present study, Isothermal Compression, solution treatment, electron backscatter diffraction (EBSD) and transmission electron microscopy (TEM) observations were carried out to correlate the microstructure and deformation-solution parameters for GH4586 superalloy. And, the recrystallized mechanisms, twin evolution, γ′ precipitation and their interaction were clearly illustrated based on the analysis of the recrystallized fraction, size of γ grains, grain boundary misorientation and length fraction of twin boundaries. The results show that the process of dynamic recrystallization is controlled by the mechanisms of sub-grain rotation and strain-induced boundary migration while the process of static recrystallization is controlled by the mechanism of subgrain boundary migration. The evolution of twin boundaries during deformation is affected by two aspects: (i) the losing of twin’s identity due to higher strain; and (ii) the nucleation and growth of new twins within the DRX grains. During deformation of GH4586 superalloy, fine γ′ precipitates have a hindered effect on the recrystallization nucleated from pre-existing subgrains and twin growth. Moreover, the recrystallization process has a noticeable influence on the formation of new twins. Conversely, the existing of these twins is also beneficial for the recrystallization.

  • Prediction model for flow stress during Isothermal Compression in α + β phase field of TC4 alloy
    Rare Metals, 2018
    Co-Authors: Shun Yang, Jiao Luo, Yin-gang Liu
    Abstract:

    Isothermal Compression of TC4 alloy was performed on a Thermecmaster-Z simulator at the deformation temperatures ranging from 1093 to 1243 K, the strain rates ranging from 0.001 to 10.000 s−1 and a maximum strain of 0.8. The experimental results show that the flow stress increases with the decrease in the deformation temperature and the increase in the strain rate. The apparent activation energy for deformation is much lower at lower strain rates than that at higher strain rates. The flow stress model considering strain compensation was established. The average relative error between the calculated flow stress and experimental results is about 7.69%, indicating that the present model could be used to accurately predict the flow stress during high temperature in α + β phase field of TC4 alloy.

  • the flow behavior and the deformation mechanisms of ti 6al 2zr 2sn 2mo 1 5cr 2nb alloy during Isothermal Compression
    Journal of Alloys and Compounds, 2016
    Co-Authors: Jiao Luo, Jianrong Gao
    Abstract:

    Abstract The effects of the processing parameters on the shapes of flow curves, the microstructural evolution and the strain rate sensitivity are analyzed via the Isothermal Compression tests of Ti–6Al–2Zr–2Sn–2Mo–1.5Cr–2Nb alloy. The Isothermal Compression is performed on a Gleeble-1500 thermal simulator in the deformation temperature range of 1103–1243 K, strain rate range of 1.0 × 10 −2 to 5.0 s −1 and strain range of 0.2–1.2. The softening mechanisms are investigated thoroughly in the α+β phase region and β phase region through the experiments of optical microscopy, scanning electron microscopy and transmission electron microscopy. Then, the correlation between the flow behavior and the microstructural evolution is discussed. The results show that more noticeable flow softening at a high strain rate (5.0 s −1 ) in the α+β phase region arises from the thermal softening, the dynamic recovery and the dynamic recrystallization of alpha phase. However, the thermal softening can no longer be considered to be the major softening mechanism at a low strain rate (1.0 × 10 −2  s −1 ). In the β phase region, the dynamic recovery and the dynamic recrystallization of β phase are main softening mechanisms. Moreover, the maximum m value of 0.3 occurs at a deformation temperature of 1163 K, a strain rate of 0.1 s −1 and a strain of 0.7, in which the microstructure is equiaxed and uniform.

  • The flow behavior and the deformation mechanisms of Ti–6Al–2Zr–2Sn–2Mo–1.5Cr–2Nb alloy during Isothermal Compression
    Journal of Alloys and Compounds, 2016
    Co-Authors: Jiao Luo, Jianrong Gao
    Abstract:

    Abstract The effects of the processing parameters on the shapes of flow curves, the microstructural evolution and the strain rate sensitivity are analyzed via the Isothermal Compression tests of Ti–6Al–2Zr–2Sn–2Mo–1.5Cr–2Nb alloy. The Isothermal Compression is performed on a Gleeble-1500 thermal simulator in the deformation temperature range of 1103–1243 K, strain rate range of 1.0 × 10 −2 to 5.0 s −1 and strain range of 0.2–1.2. The softening mechanisms are investigated thoroughly in the α+β phase region and β phase region through the experiments of optical microscopy, scanning electron microscopy and transmission electron microscopy. Then, the correlation between the flow behavior and the microstructural evolution is discussed. The results show that more noticeable flow softening at a high strain rate (5.0 s −1 ) in the α+β phase region arises from the thermal softening, the dynamic recovery and the dynamic recrystallization of alpha phase. However, the thermal softening can no longer be considered to be the major softening mechanism at a low strain rate (1.0 × 10 −2  s −1 ). In the β phase region, the dynamic recovery and the dynamic recrystallization of β phase are main softening mechanisms. Moreover, the maximum m value of 0.3 occurs at a deformation temperature of 1163 K, a strain rate of 0.1 s −1 and a strain of 0.7, in which the microstructure is equiaxed and uniform.

  • effect of the alpha grain size on the deformation behavior during Isothermal Compression of ti 6al 4v alloy
    Materials & Design, 2015
    Co-Authors: Jiao Luo, Lin Liu
    Abstract:

    Abstract The effects of alpha grain size on the flow stress, the apparent activation energy for deformation (Q) and the processing maps of Ti–6Al–4V with an equiaxed microstructure are thoroughly investigated using Isothermal Compression tests, and detailed explanation is given based on the microstructure observation and quantitative analysis. The shapes of flow curves are dependent on the microstructure characteristic of the alloy before deformation and during the deformation process. The flow stress increases with increasing equiaxed alpha phase, but decreases with increasing alpha grain size. The Q-values for d r1 and d r2 are smaller than those for d r3 and d r4 , respectively, which is possibly attributed to that Ti–6Al–4V alloy for d r1 and d r2 which exhibits a very strong grain-boundary sliding (GBS) mode besides dominant dislocation glide/climb mechanism. The local efficiency maxima and unstable regions in processing maps change with the alpha grain size, which implies that proper hot-working domains should be modified in different grain size range so as to meet the precision forging process.

Yong Niu - One of the best experts on this subject based on the ideXlab platform.

  • The correlation model between the hydrogen content and the flow stress in the Isothermal Compression of Ti600 alloy
    International Journal of Hydrogen Energy, 2011
    Co-Authors: Yong Niu, Jiao Luo
    Abstract:

    Abstract Isothermal Compression of the Ti600 alloy at the hydrogen contents of 0.16 wt%, 0.31 wt%, 0.45 wt%, 0.65 wt% and natural hydrogen was conducted at the deformation temperatures ranging from 720 °C to 1000 °C with an interval of 40 °C, the strain rates of 0.001 s−1, 0.01 s−1, 0.1 s−1, 1.0 s−1 and 10.0 s−1 and a height reduction of 50% on a Gleeble-1500D thermo-mechanical simulator. The effect of hydrogen content on the flow stress of Ti600 alloy was analyzed. A fuzzy neural network (FNN) was applied to acquire the correlation model between the hydrogen content, deformation temperature, strain rate, strain and the flow stress in the Isothermal Compression of Ti600 alloy. The present model could be used to predict the flow stress of Ti600 alloy at different hydrogen contents. The average difference of the predicted using the FNN model from the experimental flow stress in the Isothermal Compression of Ti600 alloy is 8.2%.

  • Effect of the hydrogen content on the deformation behavior in the Isothermal Compression of Ti600 alloy
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010
    Co-Authors: Jiao Luo, Yong Niu
    Abstract:

    Abstract Isothermal Compression of the Ti600 alloy at the hydrogen contents ranging from 0.16 wt% to 0.45 wt%, the deformation temperatures ranging from 800 °C to 1000 °C and the strain rates of 0.001 s−1, 0.01 s−1, 0.1 s−1, 1.0 s−1 and 10.0 s−1 was conducted on a Gleeble-1500D thermo-mechanical simulator. According to the experimental results of Ti600 alloy, the strain hardening exponent decreases with the increasing of hydrogen content. The hydrogen content, deformation temperature and strain rate affects significantly the temperature sensitivity exponent and the strain rate sensitivity exponent of Ti600 alloy, but the strain affects the temperature sensitivity exponent of Ti600 alloy slightly. The hydrogen content decreases the apparent activation energy for deformation in the α + β region of Ti600 alloy by 30%, but the effect of the hydrogen content in the β region of Ti600 alloy is slight.

  • An adaptive constitutive model in the Isothermal Compression of Ti600 alloy
    Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010
    Co-Authors: Yong Niu, Jiao Luo
    Abstract:

    Abstract The Ti600 alloy was Isothermally compressed at the deformation temperatures ranging from 800 °C to 1000 °C with an interval of 40 °C, the strain rates of 0.001 s−1, 0.01 s−1, 0.1 s−1, 1.0 s−1, 10.0 s−1 and a height reduction of 50% on a Gleeble-1500D thermo-mechanical simulator. Based on the experimental flow stress, a fuzzy neural network model (FNN model) was developed to acquire the constitutive model in the Isothermal Compression of Ti600 alloy. In the present constitutive model, the three inputs of FNN model are, respectively, the deformation temperature, the strain rate and the strain, and the output of FNN model is the flow stress. The predicted flow stress is in a good agreement with the experimental flow stress, meanwhile the predicted accuracy of flow stress in the Isothermal Compression of Ti600 alloy using the FNN model is higher than that using the regression model.

  • Deformation Behavior in the Isothermal Compression of Hydrogenated Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo Alloy
    Journal of Materials Engineering and Performance, 2007
    Co-Authors: Ying Ying Lin, Weifu Zhang, Yong Niu
    Abstract:

    The Isothermal Compression of hydrogenated Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo alloy has been carried out. The experimental result shows that the additional hydrogen significantly decreases the flow stress of Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo alloy. The minimum peak stress at deformation temperature of 830–900 °C corresponds to the hydrogen content of 0.4 wt.%, alternatively the appropriate hydrogen content raises the true strain rate up to one order of magnitude in comparison with the received Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo alloy. X-ray diffraction examination shows the appropriate hydrogen content accelerates the $${\upbeta}$$ phase transformation so as to improve the workability of this alloy. However, the hydride phase appears when the hydrogen content is about 0.734 wt.%, which increases of the flow stress in comparison to the flow stress of this alloy with hydrogen content of 0.4 wt.%.

  • deformation behavior in the Isothermal Compression of hydrogenated ti 5 6al 4 8sn 2 0zr 1 0mo alloy
    Journal of Materials Engineering and Performance, 2007
    Co-Authors: Ying Ying Lin, Weifu Zhang, Yong Niu
    Abstract:

    The Isothermal Compression of hydrogenated Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo alloy has been carried out. The experimental result shows that the additional hydrogen significantly decreases the flow stress of Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo alloy. The minimum peak stress at deformation temperature of 830–900 °C corresponds to the hydrogen content of 0.4 wt.%, alternatively the appropriate hydrogen content raises the true strain rate up to one order of magnitude in comparison with the received Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo alloy. X-ray diffraction examination shows the appropriate hydrogen content accelerates the $${\upbeta}$$ phase transformation so as to improve the workability of this alloy. However, the hydride phase appears when the hydrogen content is about 0.734 wt.%, which increases of the flow stress in comparison to the flow stress of this alloy with hydrogen content of 0.4 wt.%.

Weifu Zhang - One of the best experts on this subject based on the ideXlab platform.

  • effect of hydrogenation content on high temperature deformation behavior of ti 6al 4v alloy in Isothermal Compression
    International Journal of Hydrogen Energy, 2008
    Co-Authors: Weifu Zhang
    Abstract:

    Abstract Isothermal Compression of hydrogenated Ti–6Al–4V alloy was carried out on a Thermecmaster-Z simulator at deformation temperatures between 760 and 920 ∘ C , constant strain rate between 0.01 and 10.0 s - 1 , and a maximum height reduction of 60%. The high temperature deformation behavior of hydrogenated Ti–6Al–4V alloy was characterized based on an analysis of the stress–strain behavior, kinetics, and processing map. The smallest activation energy for deformation obtained in Isothermal Compression of hydrogenated Ti–6Al–4V alloy is 208.3 kJ/mol in the two-phase region of Ti–6Al–4V alloy with hydrogen contents of 0.2 wt%. Three unstable deformation regions were obtained by constructing the processing map of hydrogenated Ti–6Al–4V alloy with hydrogen contents of 0.2 wt%.

  • Effect of hydrogenation content on high temperature deformation behavior of Ti–6Al–4V alloy in Isothermal Compression
    International Journal of Hydrogen Energy, 2008
    Co-Authors: Weifu Zhang
    Abstract:

    Abstract Isothermal Compression of hydrogenated Ti–6Al–4V alloy was carried out on a Thermecmaster-Z simulator at deformation temperatures between 760 and 920 ∘ C , constant strain rate between 0.01 and 10.0 s - 1 , and a maximum height reduction of 60%. The high temperature deformation behavior of hydrogenated Ti–6Al–4V alloy was characterized based on an analysis of the stress–strain behavior, kinetics, and processing map. The smallest activation energy for deformation obtained in Isothermal Compression of hydrogenated Ti–6Al–4V alloy is 208.3 kJ/mol in the two-phase region of Ti–6Al–4V alloy with hydrogen contents of 0.2 wt%. Three unstable deformation regions were obtained by constructing the processing map of hydrogenated Ti–6Al–4V alloy with hydrogen contents of 0.2 wt%.

  • Deformation Behavior in the Isothermal Compression of Hydrogenated Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo Alloy
    Journal of Materials Engineering and Performance, 2007
    Co-Authors: Ying Ying Lin, Weifu Zhang, Yong Niu
    Abstract:

    The Isothermal Compression of hydrogenated Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo alloy has been carried out. The experimental result shows that the additional hydrogen significantly decreases the flow stress of Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo alloy. The minimum peak stress at deformation temperature of 830–900 °C corresponds to the hydrogen content of 0.4 wt.%, alternatively the appropriate hydrogen content raises the true strain rate up to one order of magnitude in comparison with the received Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo alloy. X-ray diffraction examination shows the appropriate hydrogen content accelerates the $${\upbeta}$$ phase transformation so as to improve the workability of this alloy. However, the hydride phase appears when the hydrogen content is about 0.734 wt.%, which increases of the flow stress in comparison to the flow stress of this alloy with hydrogen content of 0.4 wt.%.

  • deformation behavior in the Isothermal Compression of hydrogenated ti 5 6al 4 8sn 2 0zr 1 0mo alloy
    Journal of Materials Engineering and Performance, 2007
    Co-Authors: Ying Ying Lin, Weifu Zhang, Yong Niu
    Abstract:

    The Isothermal Compression of hydrogenated Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo alloy has been carried out. The experimental result shows that the additional hydrogen significantly decreases the flow stress of Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo alloy. The minimum peak stress at deformation temperature of 830–900 °C corresponds to the hydrogen content of 0.4 wt.%, alternatively the appropriate hydrogen content raises the true strain rate up to one order of magnitude in comparison with the received Ti–5.6Al–4.8Sn–2.0Zr–1.0Mo alloy. X-ray diffraction examination shows the appropriate hydrogen content accelerates the $${\upbeta}$$ phase transformation so as to improve the workability of this alloy. However, the hydride phase appears when the hydrogen content is about 0.734 wt.%, which increases of the flow stress in comparison to the flow stress of this alloy with hydrogen content of 0.4 wt.%.

  • Effect of Hydrogenation on the Microstructure during the Isothermal Compression of Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo Alloy
    Materials Science Forum, 2007
    Co-Authors: Ying Ying Lin, Yong Niu, Weifu Zhang
    Abstract:

    Isothermal Compression tests were carried out on the Ti-5.6Al-4.8Sn-2.0Zr-1.0Mo alloy with and without hydrogen. A series of experiments including the optical microstructure and TEM (Transmission Electron Microscope) were performed to the compressed samples. The results show that hydrogenation not only increases the fraction ofβ phase, but also activates the propagation of the dislocation and formation of the twins, which are benefit for plastic or superplastic formability.

Wei Zhang - One of the best experts on this subject based on the ideXlab platform.

Jinkai Yan - One of the best experts on this subject based on the ideXlab platform.

  • dynamic globularization and restoration mechanism of ti 5al 2sn 2zr 4mo 4cr alloy during Isothermal Compression
    Journal of Alloys and Compounds, 2015
    Co-Authors: Jun Luo, Jinkai Yan
    Abstract:

    Abstract Dynamic globularization and restoration mechanism of Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy during Isothermal Compression were investigated by employing a high-resolution electron backscatter diffraction technique (EBSD). Quantitative analysis was made in detail for further understanding the microstructure evolution. The results reveal that the dynamic globularization of primary α grains of Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy is accomplished by the formation of high-angle boundaries (HABs) and the penetration of the β phase during Isothermal Compression, and an increase in deformation temperature leads to a more globular microstructure. The main restoration mechanism in the β phase of Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy during Isothermal Compression is dynamic recovery (DRC) at a strain rate of 0.01 s−1, while continuous dynamic recrystallization (CDRX) occurs as the strain rate increases to 1.0 s−1/5.0 s−1 and the α grains play an important role in recrystallization. The recrystallization in the β phase of Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy during Isothermal Compression is promoted with the decreasing of deformation temperature and the increasing of strain rate. A strong 〈0 0 1〉 fiber texture develops where only DRC occurs and the deformation texture is weakened to a large extent after recrystallization of Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy during Isothermal Compression.

  • Dynamic globularization and restoration mechanism of Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy during Isothermal Compression
    Journal of Alloys and Compounds, 2015
    Co-Authors: Jun Luo, Jinkai Yan
    Abstract:

    Abstract Dynamic globularization and restoration mechanism of Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy during Isothermal Compression were investigated by employing a high-resolution electron backscatter diffraction technique (EBSD). Quantitative analysis was made in detail for further understanding the microstructure evolution. The results reveal that the dynamic globularization of primary α grains of Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy is accomplished by the formation of high-angle boundaries (HABs) and the penetration of the β phase during Isothermal Compression, and an increase in deformation temperature leads to a more globular microstructure. The main restoration mechanism in the β phase of Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy during Isothermal Compression is dynamic recovery (DRC) at a strain rate of 0.01 s−1, while continuous dynamic recrystallization (CDRX) occurs as the strain rate increases to 1.0 s−1/5.0 s−1 and the α grains play an important role in recrystallization. The recrystallization in the β phase of Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy during Isothermal Compression is promoted with the decreasing of deformation temperature and the increasing of strain rate. A strong 〈0 0 1〉 fiber texture develops where only DRC occurs and the deformation texture is weakened to a large extent after recrystallization of Ti–5Al–2Sn–2Zr–4Mo–4Cr alloy during Isothermal Compression.