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Yoko Yamabemitarai - One of the best experts on this subject based on the ideXlab platform.
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equiaxed α microstructure evolution in wrought ti 10al 1zr 1mo 1nb alloy during annealing
Journal of Alloys and Compounds, 2021Co-Authors: Shintaro Tanii, Osamu Umezawa, Yoko YamabemitaraiAbstract:Abstract Evolution of α microstructure on the thermomechanical treated Ti-10Al-1Zr-1Mo-1Nb alloy during annealing was studied. The solution-treated materials were groove-rolled or uniaxially compressed in the α+β region and annealed at 1173 K. The flow softening behavior and crystal rotation in α platelets revealed an evolution of deformation texture. The volume fraction of equiaxed α grains was increased during annealing. Especially in the material compressed at a Strain rate of 1 s−1, the equiaxed α grains developed within a shorter annealing duration than 1.8 ks. The deformation with Higher Strain rates promoted the division and fragmentation of α platelets during annealing. Transmission electron microscopy and X-ray diffraction analyses were employed to characterize dislocation components and structure, where the installed screw dislocations provided a fine substructure and high energy α/α boundaries in α platelets. The triple junction consisting of α/β boundaries and α/α boundaries may provide a site for thermal grooving, which induces the division and fragmentation of α platelets. Therefore, deformation at a Higher Strain rate is necessary in α+β processing to develop a fine equiaxed α microstructure for the Ti-10Al-1Zr-1Mo-1Nb alloy during annealing.
Osamu Umezawa - One of the best experts on this subject based on the ideXlab platform.
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equiaxed α microstructure evolution in wrought ti 10al 1zr 1mo 1nb alloy during annealing
Journal of Alloys and Compounds, 2021Co-Authors: Shintaro Tanii, Osamu Umezawa, Yoko YamabemitaraiAbstract:Abstract Evolution of α microstructure on the thermomechanical treated Ti-10Al-1Zr-1Mo-1Nb alloy during annealing was studied. The solution-treated materials were groove-rolled or uniaxially compressed in the α+β region and annealed at 1173 K. The flow softening behavior and crystal rotation in α platelets revealed an evolution of deformation texture. The volume fraction of equiaxed α grains was increased during annealing. Especially in the material compressed at a Strain rate of 1 s−1, the equiaxed α grains developed within a shorter annealing duration than 1.8 ks. The deformation with Higher Strain rates promoted the division and fragmentation of α platelets during annealing. Transmission electron microscopy and X-ray diffraction analyses were employed to characterize dislocation components and structure, where the installed screw dislocations provided a fine substructure and high energy α/α boundaries in α platelets. The triple junction consisting of α/β boundaries and α/α boundaries may provide a site for thermal grooving, which induces the division and fragmentation of α platelets. Therefore, deformation at a Higher Strain rate is necessary in α+β processing to develop a fine equiaxed α microstructure for the Ti-10Al-1Zr-1Mo-1Nb alloy during annealing.
Alan A. Luo - One of the best experts on this subject based on the ideXlab platform.
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low cycle fatigue properties of an extruded az31 magnesium alloy
International Journal of Fatigue, 2009Co-Authors: S Begum, D L Chen, Alan A. LuoAbstract:Abstract Lightweight magnesium alloys are being increasingly used in automotive and other transportation industries to achieve energy efficiency and environmental protection. Design of magnesium components requires low cycle fatigue (LCF) behavior since these applications are often subjected to cyclic loading and/or thermal stresses. The objective of this investigation was to study the cyclic deformation behavior and LCF life of a large solid extruded section of AZ31 magnesium alloy. It was observed that the alloy was cyclically stable at lower Strain amplitudes and exhibited cyclic hardening characteristics at Higher Strain amplitudes, with a cyclic hardening exponent of about 2.6 times Higher than the monotonic Strain hardening exponent. A relationship between the plastic Strain amplitude ( Δ e p 2 ) and the number of cycles (N), Δ e p 2 = α + β log ( N ) , was observed. With increasing total Strain amplitude both plastic Strain amplitude and mean stress increased and the fatigue lifetime decreased. Bauschinger effect was pronounced at Higher Strain amplitudes, resulting in asymmetric hysteresis loops due to twinning in compression during unloading and subsequent detwinning in tension during loading. Modulus during cyclic deformation was constant at the low Strain amplitude, but it decreased with increasing Strain amplitudes and increased with increasing number of cycles at the high Strain amplitudes due to the presence of pseudoelastic behavior. Fatigue parameters following the Coffin-Manson and Basquin’s equations were evaluated. Fatigue crack initiation was observed to occur from the specimen surface and crack propagation was characterized by striation-like features coupled with secondary cracks.
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Dependence of the distribution of deformation twins on Strain amplitudes in an extruded magnesium alloy after cyclic deformation
Materials Science and Engineering: A, 2009Co-Authors: C.l. Fan, Daolun Chen, Alan A. LuoAbstract:Abstract Cyclic deformation characteristics and the distribution of deformation twins in a recently developed magnesium alloy AM30 after Strain-controlled low cycle fatigue tests were studied in the loading direction along the extrusion direction. The alloy was basically cyclically stable at a lower Strain amplitude of 0.2% with low stress amplitude and small plastic Strain amplitude, while it exhibited strong cyclic hardening at a Higher Strain amplitude of 0.6%. In addition to the initially high stress amplitude and large plastic Strain amplitude, the stress amplitude increased and plastic Strain amplitude decreased significantly as cyclic deformation proceeded at the Higher Strain amplitude. Twinning in compression and detwinning in tension occurred at both Strain amplitudes, and the distribution of the residual twins observed near the fracture surface was a consequence of competition between twinning and detwinning, depending on the Strain amplitude, cyclic hardening–softening characteristics, and the plastic zone size ahead of the crack tip. In the stable cyclic deformation at the lower Strain amplitude, deformation twins appeared mostly in the area prior to the final rapid fracture, while at the Higher Strain amplitude with cyclic hardening the extensive and well-developed twins were mainly observed in the crack initiation area.
Shintaro Tanii - One of the best experts on this subject based on the ideXlab platform.
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equiaxed α microstructure evolution in wrought ti 10al 1zr 1mo 1nb alloy during annealing
Journal of Alloys and Compounds, 2021Co-Authors: Shintaro Tanii, Osamu Umezawa, Yoko YamabemitaraiAbstract:Abstract Evolution of α microstructure on the thermomechanical treated Ti-10Al-1Zr-1Mo-1Nb alloy during annealing was studied. The solution-treated materials were groove-rolled or uniaxially compressed in the α+β region and annealed at 1173 K. The flow softening behavior and crystal rotation in α platelets revealed an evolution of deformation texture. The volume fraction of equiaxed α grains was increased during annealing. Especially in the material compressed at a Strain rate of 1 s−1, the equiaxed α grains developed within a shorter annealing duration than 1.8 ks. The deformation with Higher Strain rates promoted the division and fragmentation of α platelets during annealing. Transmission electron microscopy and X-ray diffraction analyses were employed to characterize dislocation components and structure, where the installed screw dislocations provided a fine substructure and high energy α/α boundaries in α platelets. The triple junction consisting of α/β boundaries and α/α boundaries may provide a site for thermal grooving, which induces the division and fragmentation of α platelets. Therefore, deformation at a Higher Strain rate is necessary in α+β processing to develop a fine equiaxed α microstructure for the Ti-10Al-1Zr-1Mo-1Nb alloy during annealing.
Koichi Tsuchiya - One of the best experts on this subject based on the ideXlab platform.
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Strain rate effect on work hardening behavior in β type ti 10mo 1fe alloy with twip effect
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2017Co-Authors: Satoshi Emura, Xiaohua Min, Koichi TsuchiyaAbstract:Abstract The Strain rate effect (2.8 × 10 −5 –2.8 × 10 −1 s −1 ) on the tensile properties and microstructure evolution of a β-type Ti-10Mo-1Fe (wt%) alloy has been investigated. With increasing Strain rate, the yield strength increased, while the ultimate tensile strength, total elongation and uniform elongation decreased. It was found that deformation at a lower Strain rate led to an enhanced work hardening rate ( θ ). This is reflected in the decreasing Strain rate sensitivity of flow stress, m , with increasing Strain. Strain rate sensitivity was positive at a smaller Strain level ( twins and dislocations. Electron Backscattered Diffraction (EBSD) and X-ray diffraction (XRD) analyses revealed lower increasing rates of {332} twins and dislocation density at Higher Strain rates, which may be caused by adiabatic heating. This may lead to the reduced work-hardening rate on deformation at the Higher Strain rates.