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Akihiko Chiba - One of the best experts on this subject based on the ideXlab platform.
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ti 6al 4v alloy with an ultrafine grained Microstructure exhibiting low temperature high strain rate superplasticity
Materials Letters, 2013Co-Authors: Hiroaki Matsumoto, Kazuki Yoshida, Akihiko ChibaAbstract:Abstract Superplasticity in microcrystalline Ti–6Al–4V (mass%) alloys is exhibited under high temperatures more than 1123 K and low strain rates less than 10 −3 s −1 , thereby restricting their practical application to specialized areas such as aerospace. We herein identify a new type of Ti–6Al–4V alloy exhibiting low-temperature (below 973 K)–high-strain-rate (10 −2 s −1 ) superplasticity. The ultrafine-grained Ti–6Al–4V alloy was produced by simple hot orking of an α′-Martensite Microstructure alloy, and it has a great potential for application as cost-affordable superplastic Ti alloy.
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frequent occurrence of discontinuous dynamic recrystallization in ti 6al 4v alloy with α Martensite starting Microstructure
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2013Co-Authors: Hiroaki Matsumoto, Liu Bin, Sanghak Lee, Yoshiki Ono, Akihiko ChibaAbstract:The microstructural conversion mechanism in an α′ Martensite starting Microstructure during hot deformation (at 973 K (700 °C)-10 s−1) of the Ti-6Al-4V alloy is studied through detailed microstructural observations, kinetic analysis of deformation in the Microstructure, and various theoretical models. After compressing the α′ starting Microstructure at 973 K (700 °C)-10 s−1 and at a height strain of 0.8, it is observed that the α′ starting Microstructure with acicular morphology evolved into an ultrafine-grained Microstructure with an average grain size of 0.2 μm and a high fraction of high-angle grain boundaries. At the initial stage of deformation, subgrain formation in Martensite variants and the formation of new grains with high-angle boundaries at interfaces of Martensite variants, and \( \{ 10\bar{1}1\} \) twins are dominant. On increasing the height strain to 0.8, discontinuous dynamic recrystallization (DDRX) along with heterogeneous nucleation and fragmentation of grains with high-angle boundaries becomes dominant. In contrast, in the case of an (α + β) starting Microstructure, continuous dynamic recrystallization (CDRX) is dominant throughout the deformation process. Thus, we found that DDRX becomes dominant by changing the starting Microstructure from the conventional (α + β) to the acicular α′ Martensite one. This behavior of the α′ Martensite Microstructure is attributed to the considerable number of nucleation sites such as dislocations, interfaces of Martensite variants and \( \{ 10\bar{1}1\} \) twins, and the high-speed grain fragmentation along with subgrain formation in the α′ starting Microstructure during the initial stage of deformation.
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mechanical behaviors of ti v al sn alloys with α Martensite Microstructure
Journal of Alloys and Compounds, 2011Co-Authors: Hiroaki Matsumoto, Akihiko Chiba, Hiroshi Yoneda, Eric Maire, Damien Fabregue, Fumihiko GejimaAbstract:Abstract The mechanical properties and deformation behavior of Ti–V–(Al, Sn) alloys with a α′ Martensite Microstructure are examined in this work. In as-quenched Ti–V–Al alloys consisting of α′ Martensite Microstructure with compositions near α − (α + β), the cold-rolling ability drastically decreases from a reduction of more than 75% to less than 40% with an increase in Al content. While, excellent cold-rolling ability (more than 75% reduction) is seen in the constituent phases of α′ in the compositional region near β − (α + β), and α″ and β. On the other hand, in as-quenched Ti–V–Sn alloys, excellent cold-rolling ability with a reduction of more than 80% that is independent of phase constituents is seen. In α′ Martensite Ti–V–Al–Sn alloy with compositions in α − (α + β) that is tensile-deformed at a strain of 5%, a homogenous deformation substructure with straight dislocations is seen in alloy that with a low Al content. In contrast, the dislocation substructure begins to exhibit a planar configuration with increasing Al content. This change in deformation substructure due to increasing Al content is considered to cause the low ductility in α′ Martensite Ti alloy that contains high Al. On the other hand, in α′ Martensite Ti–V–Al alloy with a composition near β − (α + β), plastic deformation is found to be proceeded via the activation of the basal 〈 a 〉 slip and the { 10 1 ¯ 1 } twin with a homogenous deformation substructure. As a consequence, this deformation mode is considered to cause the high ductility in the α′ phase as compared with the equilibrium (α + β) phase.
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room temperature ductility of ti 6al 4v alloy with α Martensite Microstructure
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: Hiroaki Matsumoto, Hiroshi Yoneda, Kazuhisa Sato, Shingo Kurosu, Eric Maire, Damien Fabregue, Toyohiko J Konno, Akihiko ChibaAbstract:Abstract The Microstructures, cold-rolling abilities, and mechanical properties of a Ti–6Al–4V alloy with a α′ Microstructure were examined, and compared with these properties in alloys with the (α + β) Microstructure. The Microstructure of a Ti–6Al–4V alloy solution treated at 1373 K followed by quenching (referred to as 1373 K STQ in the following) exhibits the acicular α′ Martensite Microstructure. The alloy exhibits the (equilibrium α + α′ Martensite) bimodal Microstructure when 1223 K solution treatment is carried out followed by quenching (referred to as 1223 K STQ). In contrast, Ti–6Al–4V alloys heat treated at 1373 K or 1223 K, followed by furnace cooling (referred to as 1373 K ST-FC and 1223 K ST-FC), exhibit a lamellar (α + β) Microstructure and an equiaxed (α + β) Microstructure, respectively. The strength of the STQ specimens was found to be higher than that of the ST-FC specimens. The 1223 K STQ specimen had excellent cold-rolling ability (more than 40% reduction) and higher tensile ductility than those of the ST-FC specimens. The excellent ductility of 1223 K STQ is thought to be due to the constituent phase of the single HCP phase (α′ and α) and the fine equiaxed bimodal morphology. The compositional distribution of the V content enrichment and the decrease in the Al content in the α′ martensitic region during solution treatment at 1223 K should contribute to the excellent ductility. This work therefore suggests a useful method for improving room-temperature ductility by using industrial Ti–6Al–4V alloys with the α′ Martensite Microstructure.
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Microstructure and mechanical properties of α Martensite type ti v al alloy after cold or hot working process
Key Engineering Materials, 2010Co-Authors: Hiroaki Matsumoto, Hiroshi Yoneda, Kazuhisa Sato, Shingo Kurosu, Eric Maire, Damien Fabregue, Toyohiko J Konno, Akihiko ChibaAbstract:Ti alloys are widely utilized for industrial applications due to their excellent mechanical properties combined with low density. In general, Ti alloys are classified as , + and alloys, with further subdivision into near and metastable alloys. Quite recently, we have presented new type structural ’ Martensite (H.C.P.) Ti alloys with low Young’s modulus, high strength and excellent ductility at room temperature. In this work, we examined the Microstructure and mechanical properties of ’ Martensite type Ti-V-Al alloy after cold- or hot working process. Then, we found that deformation behavior of ’ initial Microstructure as compared with (+) initial Microstructure was different based on the results of stress-strain curves and Processing Maps under the hot working process. Further, cold rolled ’ Martensite Microstructure exhibited the refined equiaxed dislocation cell structure, thereby resulting in high strength. This result suggests the new type deformation processing (for both cold- and hot work processing) utilizing ’ Martensite in industrial Ti alloys.
Hiroaki Matsumoto - One of the best experts on this subject based on the ideXlab platform.
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ti 6al 4v alloy with an ultrafine grained Microstructure exhibiting low temperature high strain rate superplasticity
Materials Letters, 2013Co-Authors: Hiroaki Matsumoto, Kazuki Yoshida, Akihiko ChibaAbstract:Abstract Superplasticity in microcrystalline Ti–6Al–4V (mass%) alloys is exhibited under high temperatures more than 1123 K and low strain rates less than 10 −3 s −1 , thereby restricting their practical application to specialized areas such as aerospace. We herein identify a new type of Ti–6Al–4V alloy exhibiting low-temperature (below 973 K)–high-strain-rate (10 −2 s −1 ) superplasticity. The ultrafine-grained Ti–6Al–4V alloy was produced by simple hot orking of an α′-Martensite Microstructure alloy, and it has a great potential for application as cost-affordable superplastic Ti alloy.
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frequent occurrence of discontinuous dynamic recrystallization in ti 6al 4v alloy with α Martensite starting Microstructure
Metallurgical and Materials Transactions A-physical Metallurgy and Materials Science, 2013Co-Authors: Hiroaki Matsumoto, Liu Bin, Sanghak Lee, Yoshiki Ono, Akihiko ChibaAbstract:The microstructural conversion mechanism in an α′ Martensite starting Microstructure during hot deformation (at 973 K (700 °C)-10 s−1) of the Ti-6Al-4V alloy is studied through detailed microstructural observations, kinetic analysis of deformation in the Microstructure, and various theoretical models. After compressing the α′ starting Microstructure at 973 K (700 °C)-10 s−1 and at a height strain of 0.8, it is observed that the α′ starting Microstructure with acicular morphology evolved into an ultrafine-grained Microstructure with an average grain size of 0.2 μm and a high fraction of high-angle grain boundaries. At the initial stage of deformation, subgrain formation in Martensite variants and the formation of new grains with high-angle boundaries at interfaces of Martensite variants, and \( \{ 10\bar{1}1\} \) twins are dominant. On increasing the height strain to 0.8, discontinuous dynamic recrystallization (DDRX) along with heterogeneous nucleation and fragmentation of grains with high-angle boundaries becomes dominant. In contrast, in the case of an (α + β) starting Microstructure, continuous dynamic recrystallization (CDRX) is dominant throughout the deformation process. Thus, we found that DDRX becomes dominant by changing the starting Microstructure from the conventional (α + β) to the acicular α′ Martensite one. This behavior of the α′ Martensite Microstructure is attributed to the considerable number of nucleation sites such as dislocations, interfaces of Martensite variants and \( \{ 10\bar{1}1\} \) twins, and the high-speed grain fragmentation along with subgrain formation in the α′ starting Microstructure during the initial stage of deformation.
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mechanical behaviors of ti v al sn alloys with α Martensite Microstructure
Journal of Alloys and Compounds, 2011Co-Authors: Hiroaki Matsumoto, Akihiko Chiba, Hiroshi Yoneda, Eric Maire, Damien Fabregue, Fumihiko GejimaAbstract:Abstract The mechanical properties and deformation behavior of Ti–V–(Al, Sn) alloys with a α′ Martensite Microstructure are examined in this work. In as-quenched Ti–V–Al alloys consisting of α′ Martensite Microstructure with compositions near α − (α + β), the cold-rolling ability drastically decreases from a reduction of more than 75% to less than 40% with an increase in Al content. While, excellent cold-rolling ability (more than 75% reduction) is seen in the constituent phases of α′ in the compositional region near β − (α + β), and α″ and β. On the other hand, in as-quenched Ti–V–Sn alloys, excellent cold-rolling ability with a reduction of more than 80% that is independent of phase constituents is seen. In α′ Martensite Ti–V–Al–Sn alloy with compositions in α − (α + β) that is tensile-deformed at a strain of 5%, a homogenous deformation substructure with straight dislocations is seen in alloy that with a low Al content. In contrast, the dislocation substructure begins to exhibit a planar configuration with increasing Al content. This change in deformation substructure due to increasing Al content is considered to cause the low ductility in α′ Martensite Ti alloy that contains high Al. On the other hand, in α′ Martensite Ti–V–Al alloy with a composition near β − (α + β), plastic deformation is found to be proceeded via the activation of the basal 〈 a 〉 slip and the { 10 1 ¯ 1 } twin with a homogenous deformation substructure. As a consequence, this deformation mode is considered to cause the high ductility in the α′ phase as compared with the equilibrium (α + β) phase.
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room temperature ductility of ti 6al 4v alloy with α Martensite Microstructure
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2011Co-Authors: Hiroaki Matsumoto, Hiroshi Yoneda, Kazuhisa Sato, Shingo Kurosu, Eric Maire, Damien Fabregue, Toyohiko J Konno, Akihiko ChibaAbstract:Abstract The Microstructures, cold-rolling abilities, and mechanical properties of a Ti–6Al–4V alloy with a α′ Microstructure were examined, and compared with these properties in alloys with the (α + β) Microstructure. The Microstructure of a Ti–6Al–4V alloy solution treated at 1373 K followed by quenching (referred to as 1373 K STQ in the following) exhibits the acicular α′ Martensite Microstructure. The alloy exhibits the (equilibrium α + α′ Martensite) bimodal Microstructure when 1223 K solution treatment is carried out followed by quenching (referred to as 1223 K STQ). In contrast, Ti–6Al–4V alloys heat treated at 1373 K or 1223 K, followed by furnace cooling (referred to as 1373 K ST-FC and 1223 K ST-FC), exhibit a lamellar (α + β) Microstructure and an equiaxed (α + β) Microstructure, respectively. The strength of the STQ specimens was found to be higher than that of the ST-FC specimens. The 1223 K STQ specimen had excellent cold-rolling ability (more than 40% reduction) and higher tensile ductility than those of the ST-FC specimens. The excellent ductility of 1223 K STQ is thought to be due to the constituent phase of the single HCP phase (α′ and α) and the fine equiaxed bimodal morphology. The compositional distribution of the V content enrichment and the decrease in the Al content in the α′ martensitic region during solution treatment at 1223 K should contribute to the excellent ductility. This work therefore suggests a useful method for improving room-temperature ductility by using industrial Ti–6Al–4V alloys with the α′ Martensite Microstructure.
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Microstructure and mechanical properties of α Martensite type ti v al alloy after cold or hot working process
Key Engineering Materials, 2010Co-Authors: Hiroaki Matsumoto, Hiroshi Yoneda, Kazuhisa Sato, Shingo Kurosu, Eric Maire, Damien Fabregue, Toyohiko J Konno, Akihiko ChibaAbstract:Ti alloys are widely utilized for industrial applications due to their excellent mechanical properties combined with low density. In general, Ti alloys are classified as , + and alloys, with further subdivision into near and metastable alloys. Quite recently, we have presented new type structural ’ Martensite (H.C.P.) Ti alloys with low Young’s modulus, high strength and excellent ductility at room temperature. In this work, we examined the Microstructure and mechanical properties of ’ Martensite type Ti-V-Al alloy after cold- or hot working process. Then, we found that deformation behavior of ’ initial Microstructure as compared with (+) initial Microstructure was different based on the results of stress-strain curves and Processing Maps under the hot working process. Further, cold rolled ’ Martensite Microstructure exhibited the refined equiaxed dislocation cell structure, thereby resulting in high strength. This result suggests the new type deformation processing (for both cold- and hot work processing) utilizing ’ Martensite in industrial Ti alloys.
Steven J Thrush - One of the best experts on this subject based on the ideXlab platform.
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wear resistance of medium carbon steel with different Microstructures
Materials, 2021Co-Authors: Xue Han, Zhenpu Zhang, Gary C Barber, Steven J ThrushAbstract:In this research, the tribological properties of different Microstructures of medium carbon steel produced by either an austempered process or quenched-tempered process are investigated. The as-received samples with annealed Microstructure (spherodized) are austempered to obtain a bainite Microstructure or quenched-tempered to obtain a tempered Martensite Microstructure. The tribological performance of these Microstructures was studied using a ball-on-disk UMT3 tribometer. The results indicated that both bainite Microstructures and tempered-Martensite Microstructures produced better wear resistance than pearlite Microstructures. At the same hardness level, the austempered disk specimens have less cracking due to higher fracture toughness compared to quenched and tempered steel. For the disks, tempered Martensite Microstructures produced more plastic deformation compared with bainite Microstructures. Mild abrasive wear was observed on the harder disks, however, smearing wear was observed on the softer disks. Adhered debris particles were observed on the balls.
Shahram Kheirandish - One of the best experts on this subject based on the ideXlab platform.
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Effect of Austenitizing Temperature on Mechanical Properties of the Mixed Bainite - Martensite Microstructure in CrMoV Steel
2018Co-Authors: Parsa Abbaszadeh, H Saghafian, Shahram Kheirandish, Mohammad Hossein GoodarzyAbstract:The effect of austenitizing temperature on mechanical properties of the mixed bainite - Martensite Microstructure in CrMoV steel was studied in the present work. The result showed that at low austenitizing temperature (910°C - 1000°C), the mixed Microstructures containing 12-28% volume fraction of lower bainite showed higher yield and tensile strength than fully martensitic Microstructure. The partitioning of the prior austenite grain by lower bainite was found to cause a refinement of the Martensite packet size. In addition the strength of the lower bainite in the mixed Microstructure is enhanced by plastic constraint induced by the surrounding stronger Martensite. By increasing the austenitizing temperature from 1000°C to 1200°C (40min), the YS, UTS, %EL, %RA and CVN impact energy decreased for all samples. This is attributed mainly to the increase in austenite grain size and width of bainite sheaves.
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effect of bainite morphology on mechanical properties of the mixed bainite Martensite Microstructure in d6ac steel
Journal of Materials Science & Technology, 2012Co-Authors: Khodamorad Abbaszadeh, H Saghafian, Shahram KheirandishAbstract:The effect of bainite morphology on mechanical properties of the mixed bainite-Martensite Microstructure in D6AC low alloy ultra-high strength steel has been studied in the present work. For this purpose, samples austenitized at 910 °C for 40 min were quenched in three different ways. Some of the samples were directly oil-quenched, some others were quenched in salt bath at 330 °C and the remaining samples were quenched in salt bath at 425 °C for various holding times. All samples were tempered at 200 °C for 2 h. Microstructures were examined by optical microscopy (OM) and scanning electron microscopy (SEM). Fracture surfaces also were studied by SEM. Results showed that the mixed Microstructure containing Martensite and 28 vol.% of the lower bainite exhibited higher yield and tensile strengths than the fully martensitic Microstructure. This could be mainly attributed to the partitioning of the prior austenite grains by the lower bainite and enhancing the strength of lower bainite in the mixed Microstructure by plastic constraint. Charpy V-notch (CVN) impact energy and ductility were improved by increasing the volume fraction of the lower bainite. This is not the case about the mixed Microstructure containing the upper bainite and Martensite. As a result, the tensile and CVN impact properties of mixed upper bainite-Martensite Microstructure are lower than those of the fully martensitic Microstructure. Finally, fractography studies showed cleavage fracture at the surface of CVN impact specimens with martensitic and upper bainitic Microstructures confirming the tendency to brittle behavior.
Yunan Prawoto - One of the best experts on this subject based on the ideXlab platform.
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computational approach using johnson cook model on dual phase steel
Computational Materials Science, 2012Co-Authors: Yunan Prawoto, M M Fanone, Saeid Shahedi, M S Ismail, Wan Sani Wan NikAbstract:In this research, two different hypo-eutectoid steels with different carbon content and alloying elements were made into samples with dual phase ferrite Martensite Microstructure. Their morphology and the mechanical properties were then compared. Computational model varying the ferrite percentage was also proposed. The model adopts the failure rule of Johnson–Cook’s. The result shows that the difference in mechanical property was not only due to the variation of the ferrite parts in them but also due to the shapes of the constituents. It tends to follow the continuum mechanics rule. It is also concluded that modeling using two-dimensional approach is sufficient to estimate the properties of the dual phase structure.
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Effect of Prior Austenite Grain Size on the Morphology and Mechanical Properties of Martensite in Medium Carbon Steel
Journal of Materials Science & Technology, 2012Co-Authors: Yunan Prawoto, N. Jasmawati, Kasni SumeruAbstract:In industrial application, unintentional manufacturing line troubles often consequence in heating raw materials excessively, in terms of either time or temperature. One of the effects of such occurrence is a product with a variation of prior austenite grain size, even if after the heat treatment the end result is the same, Martensite. The variation of the prior austenite grain size is believed to vary the end results of the Martensite. This undesirable variation includes the variation of fatigue resistance, impact strength, yield strength, hardness, etc. This research studies the effect of the prior austenite grain size on the morphology of the Martensite Microstructure. The results show that within the typical industrial application of temperature and holding time set up, as holding time or the temperature increases, the prior austenite average diameter increases. The block and packet sizes in the Martensite also increase. The variation of mechanical property dependence on the grain size is indeed due to the different characteristics reflected in the Martensite morphology. With respect to the same area, smaller grain has more blocks and packets, which agrees with higher dislocation density verified with transmission electron microscopic evaluation.