The Experts below are selected from a list of 27060 Experts worldwide ranked by ideXlab platform
Rintaro Ueji - One of the best experts on this subject based on the ideXlab platform.
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effect of initial grain size on inhomogeneous plastic deformation and twinning behavior in high manganese Austenitic Steel with a polycrystalline microstructure
2015Co-Authors: Rintaro Ueji, Noriyuki Tsuchida, Kenji Harada, K Takaki, Hidetoshi FujiiAbstract:The grain size effect on the deformation twinning in a high manganese Austenitic Steel which is so-called TWIP (twining induced plastic deformation) Steel was studied in order to understand how to control deformation twinning. The 31wt%Mn-3%Al-3% Si Steel was cold rolled and annealed at various temperatures to obtain fully recrystallized structures with different mean grain sizes. These annealed sheets were examined by room temperature tensile tests at a strain rate of 10-4/s. The coarse grained sample (grain size: 49.6μm) showed many deformation twins and the deformation twinning was preferentially found in the grains in which the tensile axis is parallel near to [111]. On the other hand, the sample with finer grains (1.8 μm) had few grains with twinning even after the tensile deformation. The electron back scattering diffraction (EB SD) measurements clarified the relationship between the anisotropy of deformation twinning and that of inhomogeneous plastic deformation. Based on the EBSD analysis, the mechanism of the suppression of deformation twinning by grain refinement was discussed with the concept of the slip pattern competition between the slip system governed by a grain boundary and that activated by the macroscopic load.
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crystallographic orientation dependence of e martensite transformation during tensile deformation of polycrystalline 30 mn Austenitic Steel
2013Co-Authors: Rintaro Ueji, Noriyuki Tsuchida, Yoshinori Takagi, Kazunari Shinagawa, Yasuhiro Tanaka, Takashi MizuguchiAbstract:Abstract The dependence of the e martensite transformation on the crystallographic orientation during a tensile test of metastable high-manganese Austenitic Steel, Fe–30 mass% Mn, with a polycrystalline microstructure was studied. The e martensite plates were formed after the Steel yielded by slipping, and the volume fraction of the e martensite increased with increasing strain. No significant orientation dependence of the martensite formation was observed in the early stage of the tensile deformation, but when the sample was further strained up to about 30%, the tensile directions of the grains with martensite were preferentially found to be nearly parallel to the 〈111〉 direction of the austenite matrix. This orientation dependence corresponded with the orientation preferable for the development of local misorientations as detected by EBSD.
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fully recrystallized nanostructure fabricated without severe plastic deformation in high mn Austenitic Steel
2013Co-Authors: Rintaro Ueji, Rajib Saha, Nobuhiro TsujiAbstract:For the first time, a fully recrystallized nanostructure with a mean grain size of 400 nm can be fabricated without severe plastic deformation in a high-Mn Austenitic Steel. We report and discuss the evolution of the nanostructure and mechanical properties of the Steel in this paper. The nanostructured Austenitic Steel exhibit high yield strength, good strain hardening and large tensile elongation.
Nobuhiro Tsuji - One of the best experts on this subject based on the ideXlab platform.
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mesoscopic nature of serration behavior in high mn Austenitic Steel
2021Co-Authors: Sukyoung Hwang, Myeong Heom Park, Yu Bai, Akinobu Shibata, Wenqi Mao, Hiroki Adachi, Masugu Sato, Nobuhiro TsujiAbstract:Abstract We have thoroughly clarified the mesoscopic nature of serration behavior in a high-Mn Austenitic Steel in connection with its characteristic localized deformation. A typical high-Mn Steel, Fe-22Mn-0.6C (wt. %), with a face centered cubic (FCC) single-phase structure was used in the present study. After 4 cycles of repeated cold-rolling and annealing process, a specimen with a fully recrystallized microstructure having a mean grain size of 2.0 μm was obtained. The specimen was tensile tested at room temperature at an initial strain rate of 8.3 × 10−4 s−1, during which the digital image correlation (DIC) technique was applied for analyzing local strain and strain-rate distributions in the specimen. Obtained results indicated that a unique strain localization behavior characterized by the formation, propagation and annihilation of deformation localized bands, so-called Portevin–Le Chatelier (PLC) bands, determined the global mechanical response appearing as serration on the stress-strain curve. In addition, the in-situ synchrotron XRD diffraction during the tensile test was utilized to understand what was happening in the material with respect to the PLC banding. Lattice strain of (200) plane nearly perpendicular to the tensile direction dropped when every PLC band passed through the beam position, which indicated a stress relaxation occurred inside the PLC band. At the same time, the dislocation density increased drastically when the PLC band passed the beam position, which described that the material was plastically deformed and work-hardened mostly within the PLC band. All the results obtained consistently explained the serration behavior in a mesoscopic scale. The serration behavior on the stress-strain curve totally corresponded to the formation, propagation and annihilation of the PLC band in the 22Mn-0.6C Steel, and the localized deformation, i.e., the PLC banding, governed the characteristic strain hardening of the material.
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fully recrystallized nanostructure fabricated without severe plastic deformation in high mn Austenitic Steel
2013Co-Authors: Rintaro Ueji, Rajib Saha, Nobuhiro TsujiAbstract:For the first time, a fully recrystallized nanostructure with a mean grain size of 400 nm can be fabricated without severe plastic deformation in a high-Mn Austenitic Steel. We report and discuss the evolution of the nanostructure and mechanical properties of the Steel in this paper. The nanostructured Austenitic Steel exhibit high yield strength, good strain hardening and large tensile elongation.
A.s. Hamada - One of the best experts on this subject based on the ideXlab platform.
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low strain rate deformation behavior of a cr mn Austenitic Steel at 80 c
2012Co-Authors: P. Sahu, S K Shee, A.s. Hamada, L. Rovatti, T Sahu, B. Mahato, David Porter, Ghosh S Chowdhury, Leo Pentti KarjalainenAbstract:Abstract The deformation behavior of a Cr–Mn Austenitic Steel during interrupted low strain rate uniaxial tensile testing at −80 °C has been studied using X-ray diffraction (XRD), electron backscatter diffraction and transmission electron microscopy. Continuous γ → e → α′ martensite transformation was observed until failure. High dislocation densities were estimated in the austenite phase (∼1015 m−2), and for the α′-martensite they were even an order of magnitude higher. Dislocation character analysis indicated that increasing deformation gradually changed the dislocation character in the austenite phase to edge type, whereas the dislocations in α′-martensite were predominantly screw type. XRD analyses also revealed significant densities of stacking faults and twins in austenite, which were also seen by transmission electron microscopy. At low strains, the deformation mode in austenite was found to be dislocation glide, with an increasing contribution from twinning, as evidenced by an increasing incidence of ∑3 boundaries at high strains. The deformation mode in α′-martensite was dominated by dislocation slip.
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x ray diffraction study on cooling rate induced γfcc ehcp martensitic transformation in cast homogenized fe 26mn 0 14c Austenitic Steel
2007Co-Authors: P. Sahu, A.s. Hamada, R N Ghosh, L P KarjalainenAbstract:The thermal stability of a cast homogenized Austenitic Steel with basic composition Fe-26Mn-0.14C has been studied using the Rietveld entire X-ray diffraction (XRD) pattern fitting technique. The decomposition of austenite was observed to be very sensitive to the cooling rate. A very high proportion (49 to 70 pct) of e-martensites was found in the differently cooled specimens as well in the as-cast specimen. The density of various planar (stacking and twin) faults was also estimated in both e-martensites and retained austenite. The significant variation in the extent of γ fcc→e hcp martensitic transformation was interpreted in terms of athermal and isothermal martensites formed during cooling and grain size of austenite. The austenite grains were found to be comprised of a high to moderate density of stacking faults (∼10−3 to 10−2) and negligible twin fault probability (∼10−5). On the other hand, in the e-martensites, the dominant planar fault was twins (∼10−3). Approximate values of the dislocation density within the retained austenite were also evaluated using the crystallite size and root-mean-square (rms) strain values obtained from the “size-strain-shape” analyses.
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structure and microstructure evolution during martensitic transformation in wrought fe 26mn 0 14c Austenitic Steel an effect of cooling rate
2007Co-Authors: P. Sahu, A.s. Hamada, Ghosh S Chowdhury, L P KarjalainenAbstract:Structure and microstructure evolution under various cooling rates of a wrought Austenitic Steel, Fe-26Mn-0.14C (composition in mass %), were studied by the Rietveld method of X-ray diffraction pattern fitting, grain boundary characterization by electron back-scattered diffraction (EBSD) and optical microscopy. Cooling rate, density of stacking faults, and austenite grain size and grain boundaries influence the observed gamma(fcc) --> epsilon(hcp) transformation and lead to significant anisotropic X-ray line broadening. Depending on the cooling conditions, the grain boundaries are misoriented at both lower and higher angles. In the epsilon-martensites, the dominant planar fault is twins (similar to 10(-3)). The austenite grains were found to contain low to moderate density of stacking faults (similar to 10(-4)-10(-3)), which act as efficient nucleation sites of the epsilon-martensites. Both X-ray and EBSD analyses estimated negligible twins in the austenite. Approximate average dislocation densities have been estimated and correlated with the grain structure.
Ashok Kumar Srivastava - One of the best experts on this subject based on the ideXlab platform.
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microstructure and abrasive wear study of ti w c reinforced high manganese Austenitic Steel matrix composite
2008Co-Authors: Ashok Kumar SrivastavaAbstract:Abstract A high-manganese Austenitic Steel matrix composite (Fe–1.42%C–16.02%Mn–0.447%Si–0.288%Al–0.34%Cr–0.028%S–0.25%P–3.02%Ti–3.0%W, all in wt.%) reinforced with in-situ (Ti,W)C was synthesized by conventional melting and casting route. It has been found that the concentration of Ti decreases whereas the concentration of tungsten increases from core to the periphery of the (Ti,W)C particulates. The abrasive wear resistance of as-cast (Ti,W)C-reinforced composite is better than that of the as-cast high-manganese Austenitic Steel matrix material.
P. Sahu - One of the best experts on this subject based on the ideXlab platform.
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low strain rate deformation behavior of a cr mn Austenitic Steel at 80 c
2012Co-Authors: P. Sahu, S K Shee, A.s. Hamada, L. Rovatti, T Sahu, B. Mahato, David Porter, Ghosh S Chowdhury, Leo Pentti KarjalainenAbstract:Abstract The deformation behavior of a Cr–Mn Austenitic Steel during interrupted low strain rate uniaxial tensile testing at −80 °C has been studied using X-ray diffraction (XRD), electron backscatter diffraction and transmission electron microscopy. Continuous γ → e → α′ martensite transformation was observed until failure. High dislocation densities were estimated in the austenite phase (∼1015 m−2), and for the α′-martensite they were even an order of magnitude higher. Dislocation character analysis indicated that increasing deformation gradually changed the dislocation character in the austenite phase to edge type, whereas the dislocations in α′-martensite were predominantly screw type. XRD analyses also revealed significant densities of stacking faults and twins in austenite, which were also seen by transmission electron microscopy. At low strains, the deformation mode in austenite was found to be dislocation glide, with an increasing contribution from twinning, as evidenced by an increasing incidence of ∑3 boundaries at high strains. The deformation mode in α′-martensite was dominated by dislocation slip.
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x ray diffraction study on cooling rate induced γfcc ehcp martensitic transformation in cast homogenized fe 26mn 0 14c Austenitic Steel
2007Co-Authors: P. Sahu, A.s. Hamada, R N Ghosh, L P KarjalainenAbstract:The thermal stability of a cast homogenized Austenitic Steel with basic composition Fe-26Mn-0.14C has been studied using the Rietveld entire X-ray diffraction (XRD) pattern fitting technique. The decomposition of austenite was observed to be very sensitive to the cooling rate. A very high proportion (49 to 70 pct) of e-martensites was found in the differently cooled specimens as well in the as-cast specimen. The density of various planar (stacking and twin) faults was also estimated in both e-martensites and retained austenite. The significant variation in the extent of γ fcc→e hcp martensitic transformation was interpreted in terms of athermal and isothermal martensites formed during cooling and grain size of austenite. The austenite grains were found to be comprised of a high to moderate density of stacking faults (∼10−3 to 10−2) and negligible twin fault probability (∼10−5). On the other hand, in the e-martensites, the dominant planar fault was twins (∼10−3). Approximate values of the dislocation density within the retained austenite were also evaluated using the crystallite size and root-mean-square (rms) strain values obtained from the “size-strain-shape” analyses.
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structure and microstructure evolution during martensitic transformation in wrought fe 26mn 0 14c Austenitic Steel an effect of cooling rate
2007Co-Authors: P. Sahu, A.s. Hamada, Ghosh S Chowdhury, L P KarjalainenAbstract:Structure and microstructure evolution under various cooling rates of a wrought Austenitic Steel, Fe-26Mn-0.14C (composition in mass %), were studied by the Rietveld method of X-ray diffraction pattern fitting, grain boundary characterization by electron back-scattered diffraction (EBSD) and optical microscopy. Cooling rate, density of stacking faults, and austenite grain size and grain boundaries influence the observed gamma(fcc) --> epsilon(hcp) transformation and lead to significant anisotropic X-ray line broadening. Depending on the cooling conditions, the grain boundaries are misoriented at both lower and higher angles. In the epsilon-martensites, the dominant planar fault is twins (similar to 10(-3)). The austenite grains were found to contain low to moderate density of stacking faults (similar to 10(-4)-10(-3)), which act as efficient nucleation sites of the epsilon-martensites. Both X-ray and EBSD analyses estimated negligible twins in the austenite. Approximate average dislocation densities have been estimated and correlated with the grain structure.
