The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Kazuhiro Hono - One of the best experts on this subject based on the ideXlab platform.
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alloy design for the development of heat treatable high strength mg sheet alloy with excellent room temperature Formability
TMS Annual Meeting & Exhibition, 2018Co-Authors: M Z Bian, Taizo Sasaki, T. Nakata, Kazuhiro Hono, Shigeharu KamadoAbstract:To widen the application of the magnesium sheet alloys, good room temperature (RT) Formability and satisfactory strength need to be achieved. The development of heat treatable alloy can be an effective approach to simultaneously achieve the good RT Formability and satisfactory strength. In this work, we have investigated the effects of Zn content on the microstructure, stretch Formability and mechanical properties in the Mg–xZn–0.36Zr–0.32Ca (x = 3, 4, 5 wt%) sheet alloys. The as-rolled samples showed strong basal textures regardless of the Zn content. However, the decrease in the Zn content resulted in the significant texture weakening in the solution treated samples, and this leads to the improvement of the stretch Formability up to 7.3 mm in Index Erichsen value in the Mg–3.1Zn–0.36Zr–0.32Ca alloy. Subsequent artificial aging at 160 °C for 16 h slightly increased the tensile yield strength of Mg–4Zn–0.36Zr–0.32Ca alloy sheet from 176 to 194 MPa. This work has demonstrated that the Mg–Zn system is promising to achieve excellent RT Formability and high strength, however, the slow age hardening kinetics needs to be improved to make it industrially viable.
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development of heat treatable high strength mg zn ca zr sheet alloy with excellent room temperature Formability
TMS Annual Meeting & Exhibition, 2018Co-Authors: M Z Bian, Taizo Sasaki, T. Nakata, Kazuhiro Hono, Shigeharu KamadoAbstract:Lightweight magnesium (Mg) alloys have attracted considerable attention for potential applications in the automotive industries. However, the low strength or poor Formability at room temperature (RT) hinders the wider applications of wrought Mg alloy sheets. The newly developed a heat-treatable magnesium sheet alloy, Mg–0.6Zn–0.3Ca–0.1Zr (at. %), shows a large Index Erichsen value of 8.0 mm at RT in a solution treated condition. The excellent RT Formability can be ascribed to a weak basal texture. Subsequent artificial aging at 170 °C for 4 h (T6) increases the 0.2% proof strength from 165 to 213 MPa. This improvement in strength by the T6 treatment is associated with a dense distribution of Guinier–Preston zones lying on the basal planes of the Mg matrix. Our finding overcomes the trade-off relationship of the room temperature Formability and proof strength in Mg alloy sheets and this can be used as “bake hardenable” magnesium sheet alloy with excellent RT Formability.
Mamoru Mabuchi - One of the best experts on this subject based on the ideXlab platform.
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effects of group ii elements on the cold stretch Formability of mg zn alloys
Acta Materialia, 2015Co-Authors: Motohiro Yuasa, Mamoru Mabuchi, Naoki Miyazawa, Makoto Hayashi, Yasumasa ChinoAbstract:Abstract Tensile tests and Erichsen tests were carried out at room temperature on Mg–Zn and Mg–Zn–X (X = Ca, Sr or Ba) alloys to investigate the effects of group II elements on cold stretch Formability. First-principles calculations were also performed to understand the effects of group II elements on the basal and prismatic 〈a〉 slips. The flow stresses of the Mg–Zn–X alloys were lower than that of the Mg–Zn alloy. Furthermore, the addition of Ca, Sr or Ba enhanced the stretch Formability of Mg–Zn alloys. The effectiveness for this enhanced stretch Formability increased in order of decreasing atomic number of the group II elements. The enhanced stretch Formability in the Mg–Zn–X alloys can be explained by calculations of the generalized stacking fault energy (GSFE). However, the difference in stretch Formability between the Mg–Zn–Ba alloy and the Mg–Zn alloy could not be explained from the viewpoint of the GSFE. The stretch Formability of Mg alloys is suggested to be related not only to thermally activated dislocation processes, but also to athermally activated processes.
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texture and stretch Formability of a rolled mg zn alloy containing dilute content of y
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009Co-Authors: Yasumasa Chino, Kensuke Sassa, Mamoru MabuchiAbstract:Abstract Texture and stretch Formability of rolled Mg–Zn alloys containing dilute Y were investigated. Dilute Y addition effectively weakened and modified the basal texture, contributing to the enhanced stretch Formability. However, excessive Y addition promoted formation of the second phase particles, resulting in the deterioration of stretch Formability.
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stretch Formability of az31 mg alloy sheets at different testing temperatures
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: Yasumasa Chino, Hajime Iwasaki, Mamoru MabuchiAbstract:Stretch Formability of AZ31 Mg alloy sheets was investigated by Erichsen tests at room temperature and stretch forming tests at 523 K. The as-received specimens with lower Lankford value (r-value) and higher strain hardening exponent coefficient (n-value) showed excellent stretch Formability at room temperature. On the other hand, the as-received specimens with smaller grain size (higher ductility) exhibited excellent stretch Formability at elevated temperature. It is suggested that reduction of strain and plastic anisotropies related to texture intensity and texture distribution should be dominant factor for excellent stretch Formability at room temperature, and ductility related to fine grain size becomes important factor for stretch Formability at elevated temperature, at which effects of strain and plastic anisotropies are negligibly small.
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enhanced Formability at elevated temperature of a cross rolled magnesium alloy sheet
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: Yasumasa Chino, Kensuke Sassa, Akira Kamiya, Mamoru MabuchiAbstract:Abstract Relationship between texture and press Formability of AZ31 Mg alloy sheets processed by cross-roll rolling was investigated. The Erichsen values of the cross-rolled specimens showed superior press Formability compared with those of the specimens by normal-roll rolling. The superior press Formability was related to a reduction in directional dependence of the thickness-direction strain and width-direction strain normalized by the tensile-direction strain (ɛt/ɛL and ɛw/ɛL). The (0 0 0 2) plane texture for the cross-rolled specimen exhibited the low texture intensity and the narrow spread of basal planes to rolling direction. The reduction of anisotropy in the width-direction strain and the thickness-direction strain was likely attributed to activation of prismatic 〈a〉 slip and pyramidal 〈a + c〉 slip originated from the texture modifications.
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an investigation of compressive deformation behaviour for az91 mg alloy containing a small volume of liquid
Acta Materialia, 2003Co-Authors: Yasumasa Chino, Masaaki Kobata, H Iwasaki, Mamoru MabuchiAbstract:Deformation behavior and Formability of AZ91 magnesium alloy containing a small volume of liquid were investigated by compressive tests between 703 and 803 K and by forging tests between 753 and 803 K. Partial melting occurred initially at 743 K, however, the deformation mechanism changed at 773 K. Thus, the presence of liquid does not always lead to a change in deformation mechanism. The forging tests showed that excellent Formability was attained at more than 773 K. It was suggested that the liquid serves to relax the stress concentrations caused by piles of dislocations, resulting in acceleration in flow of the solid. Also, grain refinement due to dynamic recrystallization was attained. Thus, both excellent Formability and grain refinement were simultaneously attained by compressive deformation in a semi-solid state containing a small volume of liquid.
Yasumasa Chino - One of the best experts on this subject based on the ideXlab platform.
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effects of group ii elements on the cold stretch Formability of mg zn alloys
Acta Materialia, 2015Co-Authors: Motohiro Yuasa, Mamoru Mabuchi, Naoki Miyazawa, Makoto Hayashi, Yasumasa ChinoAbstract:Abstract Tensile tests and Erichsen tests were carried out at room temperature on Mg–Zn and Mg–Zn–X (X = Ca, Sr or Ba) alloys to investigate the effects of group II elements on cold stretch Formability. First-principles calculations were also performed to understand the effects of group II elements on the basal and prismatic 〈a〉 slips. The flow stresses of the Mg–Zn–X alloys were lower than that of the Mg–Zn alloy. Furthermore, the addition of Ca, Sr or Ba enhanced the stretch Formability of Mg–Zn alloys. The effectiveness for this enhanced stretch Formability increased in order of decreasing atomic number of the group II elements. The enhanced stretch Formability in the Mg–Zn–X alloys can be explained by calculations of the generalized stacking fault energy (GSFE). However, the difference in stretch Formability between the Mg–Zn–Ba alloy and the Mg–Zn alloy could not be explained from the viewpoint of the GSFE. The stretch Formability of Mg alloys is suggested to be related not only to thermally activated dislocation processes, but also to athermally activated processes.
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texture and stretch Formability of a rolled mg zn alloy containing dilute content of y
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2009Co-Authors: Yasumasa Chino, Kensuke Sassa, Mamoru MabuchiAbstract:Abstract Texture and stretch Formability of rolled Mg–Zn alloys containing dilute Y were investigated. Dilute Y addition effectively weakened and modified the basal texture, contributing to the enhanced stretch Formability. However, excessive Y addition promoted formation of the second phase particles, resulting in the deterioration of stretch Formability.
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stretch Formability of az31 mg alloy sheets at different testing temperatures
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007Co-Authors: Yasumasa Chino, Hajime Iwasaki, Mamoru MabuchiAbstract:Stretch Formability of AZ31 Mg alloy sheets was investigated by Erichsen tests at room temperature and stretch forming tests at 523 K. The as-received specimens with lower Lankford value (r-value) and higher strain hardening exponent coefficient (n-value) showed excellent stretch Formability at room temperature. On the other hand, the as-received specimens with smaller grain size (higher ductility) exhibited excellent stretch Formability at elevated temperature. It is suggested that reduction of strain and plastic anisotropies related to texture intensity and texture distribution should be dominant factor for excellent stretch Formability at room temperature, and ductility related to fine grain size becomes important factor for stretch Formability at elevated temperature, at which effects of strain and plastic anisotropies are negligibly small.
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enhanced Formability at elevated temperature of a cross rolled magnesium alloy sheet
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2006Co-Authors: Yasumasa Chino, Kensuke Sassa, Akira Kamiya, Mamoru MabuchiAbstract:Abstract Relationship between texture and press Formability of AZ31 Mg alloy sheets processed by cross-roll rolling was investigated. The Erichsen values of the cross-rolled specimens showed superior press Formability compared with those of the specimens by normal-roll rolling. The superior press Formability was related to a reduction in directional dependence of the thickness-direction strain and width-direction strain normalized by the tensile-direction strain (ɛt/ɛL and ɛw/ɛL). The (0 0 0 2) plane texture for the cross-rolled specimen exhibited the low texture intensity and the narrow spread of basal planes to rolling direction. The reduction of anisotropy in the width-direction strain and the thickness-direction strain was likely attributed to activation of prismatic 〈a〉 slip and pyramidal 〈a + c〉 slip originated from the texture modifications.
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an investigation of compressive deformation behaviour for az91 mg alloy containing a small volume of liquid
Acta Materialia, 2003Co-Authors: Yasumasa Chino, Masaaki Kobata, H Iwasaki, Mamoru MabuchiAbstract:Deformation behavior and Formability of AZ91 magnesium alloy containing a small volume of liquid were investigated by compressive tests between 703 and 803 K and by forging tests between 753 and 803 K. Partial melting occurred initially at 743 K, however, the deformation mechanism changed at 773 K. Thus, the presence of liquid does not always lead to a change in deformation mechanism. The forging tests showed that excellent Formability was attained at more than 773 K. It was suggested that the liquid serves to relax the stress concentrations caused by piles of dislocations, resulting in acceleration in flow of the solid. Also, grain refinement due to dynamic recrystallization was attained. Thus, both excellent Formability and grain refinement were simultaneously attained by compressive deformation in a semi-solid state containing a small volume of liquid.
Myounggyu Lee - One of the best experts on this subject based on the ideXlab platform.
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two stage forming approach for manufacturing ferritic stainless steel bipolar plates in pem fuel cell experiments and numerical simulations
International Journal of Hydrogen Energy, 2017Co-Authors: Hyuk Jong Bong, Jinwoo Lee, Jonghee Kim, Frederic Barlat, Myounggyu LeeAbstract:Abstract Multi-stage micro-channel forming by stamping, as a method for cost effective and efficient for mass production, was performed for ultra-thin ferritic stainless steel sheets with thicknesses of 0.1 and 0.075 mm, as a good substitute for traditional graphite bipolar plates of proton exchange membrane fuel cell. Attention was directed to enhance the final forming depth and minimize localized thinning, extremely important aspects of the micro-channel on bipolar plate, by the proposed forming process. A forming depth at the first forming stage was chosen as a process variable, and its effect on the Formability of the micro-channel at the second forming stage was experimentally investigated. Finite element simulations for the two-stage forming process were conducted to optimize the punch radius and forming depth at the first stage for improving the Formability. The comparative study between the simulations and the experimental results could validate improvements in the Formability by the proposed approach. In particular, this study could support the existence of an optimum forming depth at the first forming stage. Based on the simulation results, a mathematical model was established to identify the dominant factor needed for Formability improvement and to propose a methodology for the process optimization of the multi-stage forming.
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hole expansion Formability of dual phase steels using representative volume element approach with boundary smoothing technique
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2010Co-Authors: Ji Hoon Kim, Myounggyu Lee, Dae Yong Kim, David K Matlock, R H WagonerAbstract:A qualitative analysis was carried out on the Formability of dual-phase (DP) steels by introducing a realistic microstructure-based finite element approach. The present microstructure-based model was constructed using a mesh generation process with a boundary-smoothing algorithm after proper image processing. The developed model was applied to hole-expansion Formability tests for DP steel sheets having different volume fractions and morphological features. On the basis of the microstructural inhomogeneity observed in the scanning electron micrographs of the DP steel sheets, it was inferred that the localized plastic deformation in the ferritic phase might be closely related to the macroscopic Formability of DP steel. The experimentally observed difference between the hole-expansion Formability of two different microstructures was reasonably explained by using the present finite element model.
Sathiya C Narayanan - One of the best experts on this subject based on the ideXlab platform.
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forming limit diagram for interstitial free steels supplied by ford india motors
Materials & Design, 2007Co-Authors: R. Narayanasamy, Sathiya C NarayananAbstract:Forming limit diagrams are used by the stampers to solve sheet metal forming problems. In practice, sheet metals have been subjected to various combinations of strains. Necking during sheet metal forming sets the limit to which the sheet metal can be formed. Forming limit diagram is an effective tool to evaluate the Formability of sheet metals in various strain conditions. The information upon the Formability of sheet metals is important for both sheet metal manufactures and user. In this work, the Formability of two sheets namely, interstitial free steel sheet of thickness 0.85 mm coated and noncoated, have been studied and their suitability for forming applications have been examined. The microstructural aspects, tensile properties and Formability parameters of the above mentioned sheets were studied and the forming limit diagrams were evaluated for the above sheet metals. Strain distribution profiles obtained from the forming experiment have been analysed. The fracture surfaces of the formed samples were viewed using scanning electron microscope (SEM) and the SEM images were correlated with fracture behaviour and Formability of the sheet metals. Both the sheets have been found to possess good drawability and stretchability.
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forming limit diagram for indian interstitial free steels
Materials & Design, 2006Co-Authors: R. Narayanasamy, Sathiya C NarayananAbstract:In this work, the suitability of interstitial free steel sheets of thickness 0.6 and 1.6 mm for press forming operations were examined by obtaining the forming limit diagram. The microstructural aspects, tensile properties and Formability parameters were studied. Forming limit diagrams (FLD) were evaluated for the above sheet metals of two different thicknesses and they were compared. Strain distribution profiles were obtained from the forming experiment. The fracture surfaces of the formed samples were observed using scanning electron microscope. Using the fractography, the fracture behaviour and Formability were analyzed. The tensile properties and Formability parameters were correlated with the FLD. It was found that the Formability of both sheets is good and the sheet with 1.6 mm thickness was superior.
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forming limit diagram for interstitial free steels part i
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2005Co-Authors: R. Narayanasamy, Sathiya C NarayananAbstract:The suitability of interstitial free (IF) steels of thickness 0.9 and 1.2 mm for press forming operations were examined. The microstructural aspects, tensile properties and Formability parameters were studied. Forming limit diagrams were evaluated for the above sheet metals and they were compared. Strain distribution profiles were obtained from the forming experiment. The fracture surfaces of the formed samples were viewed using scanning electron microscope (SEM). Using the fractography, the fracture behaviour and Formability were analyzed. The tensile properties and Formability parameters were correlated with the FLD. From the analysis, it was found that IF steel having 1.2 mm thickness is superior compared to the other one.