Microstructural Features and Ductile-Brittle Transition Behavior in Hot-Rolled Lean Duplex Stainless SteelsO. Takahashi; Y. Shibui; P. G. Xu; S. Harjo; T. Suzuki; Y. Tomota, The characteristics of texture and microstructure of lean duplex stainless steels with low Ni content produced through hot rolling followed by annealing were investigated locally with electron backscatter diffraction and globally with neutron diffraction. Then, the ductile-brittle transition (DBT) behavior was studied by Charpy impact test. It is found that the DBT temperature (DBTT) is strongly affected by the direction of crack propagation, depending on crystallographic texture and microstructural morphology; the DBTT becomes extremely low in the case of fracture accompanying delamination. A high Ni duplex stainless steel examined for comparison, shows a lower DBTT compared with the lean steel in the same crack propagating direction. The obtained results were also discussed through comparing with those of cast duplex stainless steels reported previously (Takahashi et al., Tetsu-to-Hagane, 100(2014), 1150)., MDPI
QUANTUM BEAM SCIENCE, 2020年03月
Phase transition and hydrogenation properties of Ce2Ni7-type Pr2Co7 during the hydrogen absorption process
K. Iwase; K. Mori; S. Tashiro; T. Suzuki
Int. J. Hydrogen Energy, 2018年, ［査読有り］
Crystal Structure of Pr3MgNi14Dx Studied by in Situ Neutron DiffractionKenji Lwase; Kazuhiro Mori; Naoyoshi Terashita; Suguru Tashiro; Tetsuya Suzuki, The crystal structure of Pr3MgNi14D18 was determined by neutron diffraction. The determined structure of Pr3MgNi14D18 consisted of 89.0% Gd2Co7-type structure and 11.0% PuNi3-type structure. The lattice parameters of a and c of Gd2Co7-type structure were refined at 0.52903(7) nm and 3.90179(1) nm. The deuterium atoms were distributed among nine deuterium sites in both the CaCu5-type and MgZn2-type cells. The D-2 occupancy in the Pr2Ni4 octahedral sites of the CaCus-type cell was the largest (0.75) when compared with the other deuterium sites (<0.49). The deuterium content of the CaCus-type cell showed 0.75 DIM, but the D/M value of the MgZn2-type cell was 1.53. The volume expansions during deuteratiOn of the CaCus-type and MgZn2-type cells were nearly equal. The cyclic hydrogenation property of Pr3MgNi14 is comparable to that of LaNis. It is inferred that the similar expansion' ehavior of the CaCus-type and MgZn2-type cells during deuteration is the origin of this cyclic stability., AMER CHEMICAL SOC
INORGANIC CHEMISTRY, 2017年06月,
［査読有り］ Effect of Mg substitution on crystal structure and hydrogenation of Ce2Ni7-type Pr2Ni7Kenji Iwase; Kazuhiro Mori; Naoyoshi Terashita; Suguru Tashiro; Tetsuya Suzuki, The effect of Pr being substituted by Mg in Pr2Ni7 with a Ce2Ni7-type structure was investigated by X-ray diffraction (XRD) and pressure-composition (P-C) isotherm measurements. The maximum hydrogen capacity of Pr2Ni7 reached 1.24 H/M in the first absorption process. However, 0.61 H/M hydrogen remained in the sample after the first desorption and the reversible hydrogen capacity decreased to 0.63 H/M. Severe peak broadening was observed in the XRD profile of Pr2Ni7H5.4 after the first P-C isotherm cycle. The metal sublattice of Pr2Ni7H5.4 is deformed and changes from the Ce2Ni7-type structure to a lower symmetry during hydrogenation, with no detection of an amorphous phase. Pri.5MgozNi7 consists of two phases: 80% Gd2Co7-type and 20% PuNi3-type phases. Mg substitution leads to the relative stability of the Gd2Co7-type and PuNi3-type structures. The Gd2Co7-type and PuNi3-type structures are retained after the P-C isotherm. The reversible hydrogen capacity reached 1.05 H/M. The structural change during the hydrogen absorption-desorption cycle and the hydrogenation characteristics are changed by Mg atoms replacing Pr in the MgZn2-type cell., ACADEMIC PRESS INC ELSEVIER SCIENCE
JOURNAL OF SOLID STATE CHEMISTRY, 2017年03月,
［査読有り］ Microstructure Evolution during Reverse Transformation of Austenite from Tempered Martensite in Low Alloy SteelT.Shinozaki; Y.Tomota; T.Fukino and T.Suzuki, Microstructure evolution during the reverse transformation of low alloy steel consisting of lath martensite and chromium carbide was examined using in-situ electron backscatter diffraction at high temperatures. Austenite grains nucleated during the reverse transformation were categorized into two types: austenite grains nucleated along the lath boundaries with almost the same crystal orientation as the prior austenite (type A), and austenite grains nucleated at the prior austenite grain boundaries or inside the prior austenite grains with a different crystal orientation (type B). After the reverse transformation was finished, the prior austenite grains were reconstructed by the rapid growth and coalescence of type-A grains, which was called the "austenite memory phenomenon." Here, misorientation remained in the reconstructed austenite grains. Hence, upon heating to a higher temperature, type-A grains were invaded and were eventually replaced by type-B grains, resulting in a new fine-grained microstructure; this was similar to recrystallization. Therefore, these results showed that the austenite memory phenomenon occurred when the nucleation and growth of type-A grains was more dominant than those of type-B grains and that the degree of grain refinement depended on the nucleation and growth rate of the type-B grains., IRON STEEL INST JAPAN KEIDANREN KAIKAN
ISIJ International, 2017年03月01日,
［査読有り］ The Residual Stress Control of the Fastening Bolt for Bridges
Takanori Ebata; Hitoshi Yokota; Tetsuya Suzuki
2017 ACENS Asian Conference on Engineering and Natural Sciences,2017 ACENS, 2017年01月, ［査読有り］
Synthesis of PuNi3-type PrCo3 and its hydrogen absorption-desorption propertyKenji Iwase; Kazuhiro Mori; Shinnosuke Shimizu; Suguru Tashiro; Tetsuya Suzuki, We synthesized the intermetallic compound PrCo3 with the PuNi3-type structure. The structural parameters were refined by the Rietveld method. The refined lattice parameters were a = 0.5076(1) nm and c = 2.4831(6) nm. The pressure-composition (P-C) isotherm of PrCo3 was measured at 413 K. The maximum hydrogen capacity reached 0.95 H/M. Two plateaus were observed in the absorption-desorption process. The hydrogenation properties were reversible. The structure change of the hydride phase was investigated by X-ray diffraction. The space group of the full hydride phase (PrCo3H3.8) was determined to be R32; the metal sublattice of the original alloy (space group R-3m) transformed to R32 during the hydrogen absorption process. The volume expansions of the unit cell, and the CaCu5-type and MgZn2-type cells of the full hydride phase from the original alloy were 25.0%, 18.4%, and 22.7%, respectively. The structural change was accompanied by anisotropic lattice expansion. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 2016年09月,
［査読有り］ Accumulating Spot Joining of Aluminum and Copper Thin Plates by Indirect Friction Stir Joining
S. Igarashi; T.Suzuki; M. Tashiro; T. Nagano
9th Pacific Rim International Conference on Advanced Materials and Processing (PRICM9), 2016年08月, ［査読有り］
Structural change of NdNi3 during hydrogen absorption-desorption cycleKenji Iwase; Kazuhiro Mori; Suguru Tashiro; Hitoshi Yokota; Tetsuya Suzuki, The structural change of NdNi3 during the hydrogen absorption-desorption cycle and the P-C isotherm have been investigated. The maximum hydrogen capacity achieved in the first absorption process is 1.05 H/M. After the first desorption, 0.75 H/M of hydrogen capacity remains in the alloy. The trigonal crystal structure of the original alloy (R-3m) transforms to monoclinic (C2/m) in the first absorption. The crystal structure of the hydride phase remains monoclinic during the first desorption. The metal sublattice expands anisotropically during phase transformation from the alloy to the monoclinic hydride (NdNi3H4.0); a, b, and c axes expand by 8%, 7%, and 44%, respectively. The volumes of the unit cell, and the Nd2Ni4 and NdNi5 cells expand by more than 60%. Phase transformation of NdNi3H is irreversible during the first absorption-desorption cycle. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 2016年02月,
［査読有り］ Effect of Mg substitution on hydrogen absorption-desorption behavior and crystal structure of Gd2-xMgxNi7Kenji Iwase; Naoyoshi Terashita; Kazuhiro Mori; Suguru Tashiro; Hitoshi Yokota; Tetsuya Suzuki, The hydrogen absorption-desorption behavior and the crystal structure of Gd2-xMgxNi7 were investigated by pressure composition (PC) isotherm measurements and X-ray diffraction (XRD). Gd1.5Mg0.5Ni7 consists of two phases: 75% Gd2Co7-type structure and 25% PuNi3-type structure. Mg atoms substitute at the Gd site of the MgZn2-type cell in both Gd2Co7-type and PuNi3-type phases. In the hydrogen-free alloy after the PC isotherm measurement, the volumes of the (Gd/Mg)Ni-2 and GdNi5 cells of the Gd2Co7-type phase do not change appreciably, while those of the PuNi3-type phase experience shrinkage and expansion, respectively. A plateau region of Gcl(1.5)Mg(1.5)Ni(7) is observed between 0.06 H/M and 0.82 H/M. The reversible hydrogen content in the absorption desorption cycle is approximately 1.0 H/M. The enthalpy of hydride formation is evaluated as -24 kJ/mol H-2 from the Van't Hoff plot. The absorption desorption behavior is excellent even at low temperatures below 243 K. The hydrogen storage property of Gd1.5Mg1.5Ni7 is markedly improved by Mg substitution. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY, 2016年01月,
［査読有り］ Crystal structure analysis of La2Ni6CoDx during deuterium absorption process
K.Iwase; K.Mori; S.Tashiro; H.Yokota; T.Suzuki
Inorg. Chem, 2015年08月, ［査読有り］
Effects of Mg substitution on crystal structure and hydrogenation properties of Pr1−xMgxNi3
Kenji Iwasea; Naoyoshi Terashita; Kazuhiro Mori; Suguru Tashiro; Hitoshi Yokota; Tetsuya Suzuki
International Journal of Hydrogen Energy, 2014年06月, ［査読有り］
Transformation strain and texture evolution during diffusional phase transformation of low alloy steels studied by neutron diffraction
P. G. Xu; Y. Tomota; S. C. Vogel; T. Suzuki; M. Yonemura; T._Kamiyama
Reviews on Advanced Materials Science, 2013年, ［査読有り］
Development of Al-Alloy Coating for Advanced Nuclear Systems Using Lead AlloysYuji Kurata; Hitoshi Yokota; Tetsuya Suzuki, Small and medium reactors using lead alloys as coolants are one of the promising reactor concepts with improved safety because of their thermal-physical and chemical properties. This paper focuses on the development of Al-alloy coating for nuclear systems using liquid lead-bismuth eutectic (LBE). Since corrosion attack becomes severe against structural steels at high temperatures in liquid LBE, it is necessary to improve the corrosion resistance of steels. An Al-alloy coating method using Al, Ti, and Fe powders, and laser beam heating has been developed. The main defects formed in the Al-powder-alloy coating process are surface defects and cracks. The conditions required to avoid these defects are the employment of the laser beam scanning rate of 20 mm/min and the adjustment of the Al concentration in the coating layer. According to the results of the corrosion tests at 550 degrees C in liquid LBE, the Al-alloy coating layers on 316SS prevent severe corrosion attack such as grain boundary corrosion and LBE penetration observed in the 316SS without coating. The good corrosion resistance of the Al-alloy coating is based on the thin Al-oxide film, which can be regenerated in liquid LBE. From the viewpoint of the soundness of the produced Al-powder-alloy coating layers and the preservation of their corrosion resistance, it is estimated that the range of adequate Al concentration in the coating layer is from 4 to 12 wt. %. [DOI: 10.1115/1.4005989], ASME-AMER SOC MECHANICAL ENG
JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME, 2012年06月,
［査読有り］ 中性子回折によるフェライト単相鋼のひずみ時効硬化異方性の検討鈴木徹也 山中啓輔 石野まゆ子 篠原康浩 長井健介 津留英司 徐平光, The work-hardening characteristics of anisotropic tensile deformations and the corresponding residual strain changes of pre-strained ferritic steels without and with aging treatment were investigated by using angle dispersive neutron diffraction and electron backscatter diffraction pattern analysis. The plastic deformation along the pre-strained direction leads to evident work-hardening at the beginning stage, showing discontinuous yielding behavior. Comparably, the plastic deformation perpendicular to the pre-strained direction shows continuously yielding. The tensile and compressive residual strains were found in the ‹200› and ‹110› grains along the pre-strained direction, respectively. It is also found that the difference in various oriented grains after strain aging become more evident along the pre-strained direction but smaller perpendicular to the pre-strained direction, revealing a higher work hardening capability in the former case than in the latter case., The Iron and Steel Institute of Japan
鉄と鋼, 2012年06月01日,
［査読有り］ フェライト鋼の加工硬化異方性に及ぼすひずみ負荷経路とひずみ時効の影響長井健介 篠原康浩 津留英司 石野まゆ子 鈴木徹也, It has been well known that anisotropy in yield stress and the work-hardening rate is induced by pre-strain and aging. However, such an origin has not been adequately understood. In the present study, stress-strain curves in different directions were investigated after 2% pre-straining and post-heat treatment at 150°C in ferritic steel. When the applied strain path was changed to the orthogonal direction of the pre-straining path, the re-yield stress was lowered and the work-hardening rate in the low plastic strain was increased. The heat treatment following 2% pre-straining caused an increase of the re-yield stress in the parallel direction to the pre-strain and caused no change on the re-yield stress in the orthogonal direction. The work-hardening rate was increased in both directions after the heating. Electron back scatter diffraction pattern (EBSP) analysis was also conducted to measure the kernel average misorientation (KAM) value, which corresponded to the density of the geometrically necessary dislocation, on each [hkl]-oriented family grain for the pre-strained and the post-heated materials. The EBSP results indicated that heterogeneous work-hardening behavior among the [hkl]-oriented family grains could strongly effect the anisotropy induced by strain path change and aging., The Iron and Steel Institute of Japan
鉄と鋼, 2012年06月01日,
［査読有り］ Control of Aluminum Concentration on Iron Surface by Powder Eutectic Coating Using Laser-HeatingMayuko Ishino; Tetsuya Suzuki, A method for coating iron with a mixture of aluminum, titanium and iron powder was successfully developed using laser-heating. The aluminizing process included control of the aluminum concentration on the iron surface. A double heating process is considered to be effective for homogenization of the coated layer. © 2012 The Japan Institute of Metals.
Materials Transactions, 2012年05月25日,
［査読有り］ Corrosion Experiments and,Development of Aluminum-Alloy,Coating on Type 316SS for Nuclear,Systems Using Liquid Lead-BismuthY. Kurata; H. Yokota; T. Suzuki, An Al-alloy coating method using Al, Ti and Fe powders and the laser beam heating has been developed for nuclear systems using liquid lead-bismuth eutectic (LBE). Main defects formed in the coating process were surface defects and cracks. It was effective to decrease a laser beam scanning rate to 20 mm/min to avoid surface defects. It was necessary to adjust the Al concentration in the coating layer to be lower than 12 wt.% in order to avoid significant cracking. A static corrosion test was conducted in liquid LBE at the controlled oxygen concentrations of 10(-6)-10(-3) wt.% at 550 degrees C for 3000 h. The Al-alloy coating layer on 316SS prevented severe corrosion attack such as Ni dissolution, partial loss of grains and LBE penetration which were observed in 316SS without AI-alloy coating. Liquid LBE penetrated into the surface defects formed in the Al-alloy coating layers produced using a laser beam with the scanning rate of 60 mm/min. The AI-alloy coating layer, which was formed without surface defects and cracks under the optimum condition of the scanning rate of 20 mm/min, exhibited good corrosion resistance in liquid LBE. (C) 2012 Elsevier B.V. All rights reserved., ELSEVIER SCIENCE BV
Journal of Nuclear Materials, 2012年,
［査読有り］ Development of Aluminum Alloy,Coating for Advanced Nuclear Systems Using Lead AlloysKurata Yuji; Yokota Hitoshi; Suzuki; Tetsuya, Small and medium reactors using lead alloys as coolant are one of the promising reactor concepts with improved safety because of their thermal-physical and chemical properties. This paper focuses on development of Al-alloy coating for nuclear systems using liquid lead-bismuth eutectic(LBE). Since corrosion attack becomes severe against structural steels at high temperatures in liquid LBE, it is necessary to improve corrosion resistance of steels. An Al-alloy coating method using Al, Ti and Fe powders, and laser beam heating has been developed. Main defects formed in an Al-powder-alloy coating process are surface defects and cracks. Conditions required to avoid these defects are employment of the laser beam scanning rate of 20 mm/min and adjustment of the Al concentration in the coating layer. According to results of the corrosion tests at 550 C in liquid LBE, the Al-alloy coating layers on 316SS protect severe corrosion attack such as grain boundary corrosion and LBE penetration observed in 316SS without coating. The good corrosion resistance of the Al-alloy coating is based on the thin Al-oxide film which can be regenerated in liquid LBE. From the viewpoints of the soundness of produced Al-powder-alloy coating layers and preservation of their corrosion resistance, it is estimated that the range of the adequate Al concentration in the coating layer is from 4 to 12 wt%., AMER SOC MECHANICAL ENGINEERS
ASME 2011 Small Modular Reactors Symposium (SMR 2011),Hyatt Regency on Capitol Hill (ワシントンDC,米国), 2011年09月28日
Applicability of Al-Powder-Alloy Coating to Corrosion Barriers of 316SS in Liquid Lead-Bismuth EutecticY. Kurata; H. Sato; H. Yokota; T. Suzuki, A new Al-alloy coating method using Al, Ti and Fe powders has been applied to 316SS in order to develop corrosion resistant coating in liquid lead-bismuth eutectic: (LBE). The 316SS plates with coating layers of different Al concentrations were exposed to liquid LBE with controlled oxygen concentrations of 10(-6) to 10(-4) mass% at 823 K for 3600 ks. While surface oxidation and grain boundary corrosion accompanied by liquid LBE penetration are observed in 316SS without Al-alloy coating, the Al-alloy coating is effective to protect such severe corrosion attacks in liquid LBE. Although the coating layer containing 2.8 mass% Al does not always keep sufficient corrosion resistance, good corrosion resistance is obtained through the Al-oxide film formed in liquid LBE in the coating layer where the average Al concentration is 4.2 mass%. Cracks are formed in the coating layer containing 17.8 mass% Al during the coating process. The Al-powder-alloy coating applied to 316SS is promising as a corrosion resistant coating method in liquid LBE environment. [doi:10.2320/matertrans.M2010337], JAPAN INST METALS
Materials Transactions, 2011年,
［査読有り］ Development of Aluminum Powder Alloy Coating for Innovative Nuclear Systems with Lead-bismuth
Kurata Yuji; Sato Hidetomo; Yokota; Hitoshi; Suzuki Tetsuya
OECD/NEA International Workshop on Structural Materials for Innovative Nuclear Systems (SMINS-2),Daejeon、 Republic of Korea (大田、韓国), 2010年08月30日
High Tensile Strength of Low-Carbon Ferritic Steel Subjected to Severe Drawing
T. Suzuki; Y. Tomota; A. Moriai; H. Tashiro
Materials Transactions, 2009年05月25日, ［査読有り］
Hierachical characterization of heterogeneous deformation behavior of lamellar pearlite in eutectoid steelY. Adachi; S. Morooka; H. Igari; T. Suzuki; Y. Tomota, Heterogeneous deformation behavior of lamellar pearlite in a eutectoid steel was studied with a particular attention to the microstractural hierarchy. In- situ neutron diffraction study demonstrated that the applied external stress was partitioned both (1) between cementite lamella and ferrite, which causes so- called phase stress and (2) among ferrite with a different orientation, which causes intergranular stress. In addition to the two types of internal stress, EBSD analysis revealed that the local deformation proceeds differently depending on the cementite lamella direction as well, which might cause (3) cementite lamella direction-driven intergranular stress. Even within a colony where the cementite lamella direction is identical, local deformation proceeds inhomogeneously at a lamella level, which likely causes cementite lamella imperfection-driven intergranular stress. The reason for the heterogeneous deformation behavior at each scale level was discussed from the view point of local microstructure heterogeneity characterized by TEM and 2D/3D EBSD analyses.
Netsu shori, 49, Special issue, 2009年,
［査読有り］ In Situ TOF Neutron Diffraction for Isothermal Ferrite Transformation during Thermo-Mechanically Controlled Process of Low Alloy Steel
P.G.Xu; Y.Tomota; T.Suzuki; M.Yonemura; E.C.Oliver
Netsu shori, 49, Special issue, 2009年, ［査読有り］
Development of data analysis system of angular dispersive neutron diffraction for stress and microstructural parameters in deformed steelsSusumu Ryufuku; Tetsuya Suzuki; Hiroshi Suzuki; Yo Tomota, A data analysis system has been developed to determine texture, lattice strain, block (or grain) size and dislocation density from neutron diffraction profiles obtained by an angular dispersive method. The texture is evaluated from the integrated area of the curve-fitted quasi Voigt function for experimental profiles. The block size and dislocation density are obtained by profile analyses based on an integral breadth method as well as a Fourier coefficient method. The obtained results of lattice strain, block size and dislocation density are superposed onto the orientation pole figure as output results. The developed system was applied to a cold-rolled SUS316 steel and drawn carbon steel wires to examine its usefulness., IRON STEEL INST JAPAN KEIDANREN KAIKAN
TETSU TO HAGANE-JOURNAL OF THE IRON AND STEEL INSTITUTE OF JAPAN, 2008年04月,
［査読有り］ 中性子回折角度分散法による塑性加工を受けた鋼の応力・組織因子解析システムの開発
龍福進、鈴木徹也、鈴木裕士、友田陽
鉄と鋼, 2008年, ［査読有り］
Bulk Texture Measurement of Interstitial-Free Annealed Steel using Gaussian Integrated Intensities of Neutron Diffraction SpectraP.G.Xu; Y. Tomota; H. Suzuki; T. Suzuki; S. Machiya; F. X. Yin, {110}, {200} and {211} neutron diffraction profiles of an interstitial-free annealed steel sheet were measured on 5 x 5 degrees stereographic angle grids, and several evaluation methods of diffraction intensity were employed to calculate the bulk texture, including the peak intensity at a constant 2theta angle, the simply summed intensity in a constant 2theta angle spread and the Gaussian integrated intensity obtained by single peak fitting of each profile. The comparison among differently evaluated bulk textures shows that a stronger {111} < UVW > fiber component and a weaker {001} < 110 > rotated cube component appear in the texture of investigated steel and the Gaussian integrated intensity method with proper coefficient constraints possesses a higher sensitivity to both weak texture components and strong ones. The crystallographic orientation maps obtained from electron backscattering diffraction and the bulk textures estimated from X-ray diffraction confirm the feasibility of the neutron bulk texture based on the Gaussian integrated intensity, suggesting that it can be suitably utilized to evaluate the global orientation distribution characteristics of heterogeneous materials. [doi: 10.2320/matertrans.MRA2008086], JAPAN INST METALS
Materials Transactions, 2008年,
［査読有り］ Work Hardening Mechanism of Martensite Steel Studied by In-situ Neutron Diffraction during Tensile Deformation
S. Morooka; PG. Xu; T. Suzuki; Y. Tomota; T. Kamiyama
Proc. of The 1st International Symposium on Steel Science, 2007年, ［査読有り］
レーザー加熱を用いた鉄の局所表面アルミニウム粉末被覆
鈴木徹也、田家真紀子、森田友晴、林照剛、村上浩二、友田陽、前川克廣
鉄と鋼, 2007年, ［査読有り］
Deformation Behavior of Tempered Martensite Steel by Neutron Diffraction
S. Morooka; Y. Tomota; T. Suzuki; T. Kamiyama
Proc. of The 2nd International Student Conference at Ibaraki University, 2006年
Strength and deformation behavior of bulky cementite synthesized by mechanical milling and plasma-sinteringT.Terashima; Y.Tomota; M.Isaka; T.Suzuki; M.Umemoto; Y.Todaka, Deformation behavior of bulky cementite was investigated by compression, bending and tension tests at various temperatures and strain rates. Specimens of cementite {(Fe0.95Mn0.05)(75)C-25} were prepared by plasma-sintering from a mixture of mechanically milled Fe, Mn and graphite powders. The maximum compressive strength observed was 3.2 GPa at 573 K. At room temperature, specimens exhibited brittle fracture under compression where the fracture strength was between 2 and 3 GPa. At elevated temperatures under all types of loading modes, specimens showed high ductility, where grain boundary sliding was the dominant deformation mechanism because of the favorable grain size for superplasticity (less than 1.0 mu m). (c) 2006 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
Scripta Materiallia, 2006年,
［査読有り］ Multi-scaled heterogenetity and influence of texture on plastic flow of pearlite steelsS Morooka; T Suzuki; Y Tomota; Y Shioia; T Kamiyama, Pearlite is composed of ferrite and cementite with different strengths, Even in the ferrite matrix.,stress must be different front grain to grain depending on the crystal orientation which is called block stress. The ferrite block stress and phase stress in two pearlite steels with a strong, < 110 > fiber texture or a weak texture were studied by using a time of flight method of in situ neutron diffraction during tensile deformation. It is found that the texture influences the block stress particularly in the transverse direction., IRON STEEL INST JAPAN KEIDANREN KAIKAN
TETSU TO HAGANE-JOURNAL OF THE IRON AND STEEL INSTITUTE OF JAPAN, 2005年11月,
［査読有り］ Dynamic recrystallization behavior in martensite in 18Ni, 17Ni-0.2C and SM490 steelsYZ Bao; Y Adachi; Y Toomine; T Suzuki; PG Xu; Y Tomota, The 18Ni, 17Ni-0.2C and low carbon (SM490) steels were quenched after austenitization to obtain full martansite structure. Then specimens were heated rapidly up to various temperatures below As followed by compression with various strain rates. During hot deformation, some specimens show dynamic recrystallization, which is well summarized by using Zener-Hollomon (Z) parameter. The Z-values corresponding to the occurrence of dynamic recrystallization depend on chemical compositions of mantensite steels and are much higher than those for IF steel. The dynamic recrystallization observed is so-called continuous recrystallization which is different from discontinous recrystallization in the IF steel; subgrains change to grains with high angle boundaries during deformation. The grain size changes with Z-value and sub-micron sized grains were obtained in the 17Ni-0.2C steel., IRON STEEL INST JAPAN KEIDANREN KAIKAN
TETSU TO HAGANE-JOURNAL OF THE IRON AND STEEL INSTITUTE OF JAPAN, 2005年07月,
［査読有り］ Plasma nitridation of aluminized high purity ironK Murakami; N. Nishida; K. Osamura; Y. Tomota and T. Suzuki, Surface treatment of high-purity iron by powder liquid coating aluminization and plasma nitridation is investigated with respect to the mechanism of hardening and nitrogen diffusion. Grain boundaries in the aluminized layer are found to be preferentially nitrided in the early stage of nitridation, accompanied by the formation of gamma '-Fe4N platelets in the substrate. Aluminization and nitridation increase the hardness from HV110-120 for the original alpha-Fe(Al) to HV1200-1500 for the modified specimen, which consists of an alpha-Fe(Al) matrix with gamma '-Fe4N and rocksalt AIN. Transmission electron microscopy observation reveals the AIN to be present in the form of platelets of 2-3 nm in thickness with an orientational relationship of (001)(alpha)//(001)(AIN) and [110](alpha)// [100](AIN) (Baker Nutting relationship). The kinetics of plasma nitridation is formulated, and good agreement with the experimental results is obtained when first- or second-order reactions are assumed for the formation of AIN under constant N flux at the surface. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
Acta Materiallia, 2005年05月,
［査読有り］ High oxidation-resistance coating for steel by using aluminum and titanium powdersT Suzuki; S Terada; Y Tomota, A coating method for steel using a mixture of Al and Ti powders has been developed. Pure iron and a carbon steel (JIS-S45C) were successfully coated by the new method, where the coated layer consisted of iron aluminide: Al2TiFe, FeAl, etc. The thickness and chemical compositions of the layer were influenced by heating history and mixing weight ratio of Al and Ti powder. The coated specimen showed neither cracking nor peeling after cyclic heating test between 293 and 973K in air, revealing high oxidation resisitance., IRON STEEL INST JAPAN KEIDANREN KAIKAN
TETSU TO HAGANE-JOURNAL OF THE IRON AND STEEL INSTITUTE OF JAPAN, 2005年01月,
［査読有り］ Improvement in the oxidation of TiAl by molten salt boronizingH Yokota; T Suzuki, The high temperature oxidation resistance of high specific strength intermetallic compound TiAl was improved by boronizing using chrolide and boride molten salt. The molten salt process has some remarkable characteristics as follows; 1) very simple process, 2) the atomosphere doesn't effect on the chemical reaction in the liquid, 3) specimen is fully dipped into the treatment liquid. TiB2 and Al3Ti layers were produced on the surface of TiAl by this process. The dense and protective Al2O3 phase was observed on the Al3Ti layer. The boronized TiAl was investigated in continuous and cyclic oxidation test at 1173 K and 1123 K. The mass gain due to oxidation of TiAl decreased by boronizing, where no pealing was observed during oxidation test., IRON STEEL INST JAPAN KEIDANREN KAIKAN
TETSU TO HAGANE-JOURNAL OF THE IRON AND STEEL INSTITUTE OF JAPAN, 2005年01月,
［査読有り］ AlおよびTi素粉末を用いた鉄鋼材料の耐酸化被覆
鈴木徹也,寺田真一,友田陽
鉄と鋼, 2005年01月
溶融塩ホウ化処理によるTiAlの耐酸化性改善
横田仁志,鈴木徹也
鉄と鋼, 2005年01月
粉末液相被覆法を用いたAl拡散浸透およびプラズマ窒化処理による炭素鋼および合金工具鋼の表面改質村上浩二; 西田典秀; 長村光造; 鈴木徹也; 友田陽, 炭素鋼S45Cと合金工具鋼SKD61に対して,粉末液層被覆によるAl拡散浸透ならびにプラズマ窒化処理を行うことで,以下の結果を得た。
(1)Al拡散浸透処理の初期段階において,S45C表面にはFe
2Al
5が
c軸を基板面法線に揃えて生成した被覆層が形成される。その後,被覆層から拡散層にAlが供給され,被覆層はAl濃度の低下に伴ってFeAl
2,α-Feへと変態するとともに,α-Feの拡散層がγ-Feの基板内部に向かって成長する。この時,α-Feの固溶限を超えたCはγ-Fe側へ押し出されるとともに,拡散層終端部のAl濃度は系に存在するCの影響によって,高純度Fe基板の場合よりも高い値を示す。
(2)SKD61においても同様にα-Feの拡散層が柱状生成するが,Al拡散浸透処理温度(1303K)においても安定なV炭化物およびVとCrの複炭化物がα-Fe中に残留した組織が得られる。
(3)SKD61に対するAl拡散浸透処理後のプラズマ窒化処理により,Al拡散浸透部が窒化されることでHV1200～1600の硬さが得られ,直下の窒化層ではHV1200から単調に硬さが減少し,基板硬さ(HV570)に至る硬さ推移曲線が得られる。改質層の表面XRDにおいて,窒化前の状態から大きくひずんだα-Feならびにε-Fe
3N,γ'-Fe
4Nが同定されるが,Alの存在状態を特定することは困難で,ウルツ鉱構造としても岩塩構造としても有意な量のAINは確認されない。, 社団法人日本鉄鋼協会
鉄と鋼, 2005年01月
18Ni、17Ni-0.2CおよびSM490鋼マルテンサイトの動的再結晶挙動
包耀宗; 足立吉隆; 遠峰裕二; 鈴木徹也; 徐平光; 友田陽
鉄と鋼, 2005年, ［査読有り］
Dynamic recrystallization by rapid heating followed by compression for a 17Ni-0.2C martensite steelY.Z. Bao; Y. Adachi; Y. Toomine; P.G. Xu; T. Suzuki; Y. Tomota, A 17Ni-0.2C martensite steel was rapidly heated below the austenite formation temperature and deformed ill compression. Continuous dynamic recrystallization was observed. The behavior is similar to that in a ferrite-pearlite steel but the onset strain is much smaller. Sub-micron ferrite grains were obtained through the dynamic recrystallization. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
Scripta Materialia, 2005年,
［査読有り］ パーライト鋼の塑性変形挙動に及ぼす階層的不均一変形と集合組織の影響
諸岡聡; 鈴木徹也; 友田陽; 塩田佳徳; 神山崇
鉄と鋼, 2005年, ［査読有り］
Residual stress measurement by neutron diffraction inside a steel bar quenched after induction heatingH Tokuda; Y Tomota; T Suzuki; K Kawasaki; A Moriai; N Minakawa; Y Morii, The residual stress of a quenched steel bar with induction heating was measured by neutron diffraction. The conventional X-ray sin 2 V method was also used and three dimensional stress condition was estimated from plane-stress data obtained by a progressive polishing technique. Good agreements were found between the results by the neutron and X-ray methods. Improvements of the neutron stress measurement are discussed., IRON STEEL INST JAPAN KEIDANREN KAIKAN
TETSU TO HAGANE-JOURNAL OF THE IRON AND STEEL INSTITUTE OF JAPAN, 2004年12月,
［査読有り］ 中性子回折による高周波焼入棒鋼の残留応力測定
徳田玄聖,友田陽,鈴木徹也,川崎一博,盛合敦,皆川宣明、森井幸生
鉄と鋼, 2004年12月
Recovery and recrystallization behavior of a ferrite steel after large strain deformation
M.Uno; T.Suzuki; Y.Tomota; A.Moriai; N; Minakawa; Y.Morii; H.Tashiro and K.Nakamura
The 4th Korea – Japan Meeting on Neutron Science, 2004年02月
Aluminization of high purity iron and stainless steel by powder liquid coatingKoji Murakami; Norihide Nishida; Kozo Osamura; Yo Tomota and Tetsuya Suzuki, Powder liquid coating is investigated metallographically as an aluminization technique for high-purity iron [Acta Mater., ill press] and stainless steel. In this process, Fe2Al5 forms initially during heat treatment, with c axis preferentially aligned with the sample normal. In Fe-18mass%Cr alloy, Cr exhibits almost the same concentration profile as Fe except for the temporary Formation of a Cr5Al8 network in the early stage of heat treatment. Fe-25Cr-18Ni alloy forms a thinner aluminized layer compared to the other substrates, and contains an Al-Ni-rich layer and spherical precipitates (ordered B2). The diffusion of Al and Ni in the system (B2/bcc/fcc) is simulated using a new formulation of the diffusion equation for the tertiary Fe-Al-Ni system taking the concentration-dependent interdiffusion coefficient into account. The bcc layer is found to be predominantly in a steady state due to the large interdiffusion coefficients, and characteristic uphill diffusion of Al in the B2 layer is attributed to the existence of Ni. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved., PERGAMON-ELSEVIER SCIENCE LTD
Acta Materialia, 2004年
中性子回折によるパーライト組織鋼における加工硬化の考察蟹江厚臣、友田陽、鈴木徹也、鳥居周輝、盛合敦、皆川宣明、森井幸生、神山崇, The work hardening and the internal stress averaged in each constituent, so called "phase stress" in a pearlite steel were studied by means of neutron diffraction techniques, time-of-flight (TOF) and angler dispersion (AD) methods. The overall diffraction profiles obtained by the TOF method indicates that the cementite (122) and feirrite (110) peaks are preferable to be employed for the in situ neutron diffraction with the AD method during tensile testing. The stress partitioning between cementite and ferrite after the onset of plastic deformation is evidently found. Hence, the high work-hardening of the pearlite structure is demonstrated to be caused by the generation of phase stress. The influence of ferrite block'orientation on the residual phase stress after tensile deformation is shown. Then, the heterogeneous plastic flow at several classes is speculated, which makes complicate to estimate the stress in each constituent from (hkl) lattice plane strains measured., 社団法人日本材料学会
日本材料学会誌, 2004年
Strength Anisotropy and Residual Stress in Drawn Pearlite Steel WireTetsuya Suzuki; Y. Tomota; M. Isaka; A. Moriai; N. Minakawa and Y. Morii, Strength anisotropy is found by tensile and compressive tests for a drawn pearlite steel wire, where the compressive tests are performed for prepared specimens along directions of 0, 45 and 90 degrees with respect to the drawing direction. The influence of annealing on such anisotropic strength is also examined. To make clear the origin of the strength anisotropy, texture and residual strain are measured using neutron diffraction. It is revealed that residual stresses in the ferrite and cementite phases are the cause of strength anisotropy., IRON STEEL INST JAPAN KEIDANREN KAIKAN
ISIJ Int., 2004年
In situ neutron diffraction under tensile loading for heavily drawn steel wires with ultra-high strength
Yo Tomota; A. Kanie; Y. Siota; T. Suzuki; A. Moriai; N. Minakawa; Y. Morii
Acta Materialia, 2004年
Anisotropic Residual Stresses in a Pearlitic Steel after Tensile Deformation
T.Suzuki; Y.Tomota; A.Moriai; N.Minakawa; Y.Morii
ATEM’03, 2003年09月
Heterogeneous Deformation Behavior of Pearlite Steels Studied by Neutron DiffractionY.Tomota; A.Kanie and T.Suzuki, When plastic deformation is given to a pearlite steel, misfit strain generates between cementite and ferrite accompanying phase stress. Inhomogeneous plastic flow also takes place due to different [hk1] orientions of blocks resulting in generation of block stress as well as presumably due to different directions of lamellae in a bolck, colony stress. Neutron diffraction enables us to determine the phase stress and the block stress averaged within a whole specimen and to obtain some information on lamellar stress. In situ neutron diffraction measurements were carried out during tensile testing for variously heat-treated ferrite-cementite steels and the above internal stresses yielded by the inhomogeneous plastic deformation are discussed focusing on their effects on the yield strength and work hardening. The effects of volume fraction and shape of cementite on flow stress are well understood from the phase stress., TRANS TECH PUBLICATIONS LTD
Materials Science Forum Vols. 426-432, 2003年
Powder eutectic coating with Al3Ti for steelsH Kafuku; Y Tomota; M Isaka; T Suzuki, Plates and round bars made of a pure iron or a carbon steel (JIS-S45C) have successfully been coated with Al3Ti powder by the "powder eutectic coating" method. The coated layers are found to show graded microstructures, where the concentrations of Fe, Al, and Ti change gradually from the surface toward the inside of a specimen. The microstructure of the coated layer consists of Al3Ti, 73 (Al22Fe3Ti8), tau2 (Al2FeTi), and B2 (FeAl). When the coated specimens were subjected to heat-cycling tests between 293 and 973 K, they showed no cracking, no peeling. little oxidation, and no significant changes in microstructure., SPRINGER
METALLURGICAL AND MATERIALS TRANSACTIONS A-PHYSICAL METALLURGY AND MATERIALS SCIENCE, 2002年10月,
［査読有り］ Evolution of high aspect ratio grains in a TiAl-based alloy by directional grain growthT Tsujimoto; T Matsui; T Suzuki; Y Tomota; K Shibue; T Furuyama, A concept of microstructural control named "directional grain growth" (DGG) has been proposed. In this method, local phase transition and grain growth are utilized for controlling grain shape and grain orientation in a restricted region for an inhomogeneous material in chemical composition which is given directionality by plastic deformation. In heat treatment for DGG, a seed grain grows preferentially in a shaped region without precipitates by being held at a relatively low temperature and then enlarges further by encroaching the surrounding region where precipitates vanish gradually with temperature elevating at a slow rate. Such a DGG heat treatment was applied to a Ti-45.6at%Al-1.7at.%Mn alloy fabricated by reactive sintering of an extruded mixture of elemental powders and contained inevitably directional inhomogeneity. As a result, a structure was obtained consisting of giant columnar grains of Al-bearing alpha Ti phase of several mm in length, 6.0 7.0 in aspect ratio and a preferred orientation. The axis of the columnar grains was approximately perpendicular to [0001](alpha). (C) 2001 Elsevier Science Ltd. All rights reserved., ELSEVIER SCI LTD
INTERMETALLICS, 2001年02月,
［査読有り］ Anisotropy in strength of a TiAl base polycrystal with unidirectionally oriented lamellaeT Suzuki; T Fukuyama; M Tada; Y Tomota; T Tsujimoto, A Ti-44.1 at%Al-1.6 at%Mn alloy with a unidirectionally oriented lamellar structure was made by using heavy extrusion of a mixture of titanium and Al-Mn alloy powder followed by reactive sintering under HIP. Compression tests were performed for 5 x 5 x 6 mm(3) specimens prepared in such a way that the angle between the extrusion direction and the compression axis became 0 degrees, 30 degrees, 45 degrees, 60 degrees or 90 degrees. The yield strength at 293 K is round to strongly depend on the above angle, i.e., the 0 degrees specimen shows the highest strength, the 90 degrees specimen the second while the other specimens show much lower strengths. A similar anisotropic yield strength is observed for the results obtained at 1073 K although the strength of the 0 degrees specimen is much higher than that in the 90 degrees one. Anisotropic deformation behavior observed in the present investigation is discussed in comparison with that for TiAl polysynthetically twinned crystals., JAPAN INST METALS
MATERIALS TRANSACTIONS JIM, 2000年10月,
［査読有り］ Functionally graded eco-coating for steels by using AIM powderH Kafuku; M Isaka; T Suzuki; Y Tomota, Plates and round bars made of a pure iron or a carbon steel (JIS-S45C) have successfully been coated with Al3Ti powder by "powder eutectic coating" method. It is possible to achieve high toughness and high oxidation resistance without using the pessimistic elements such as Zn, Cr, Ni and so on. The coated layers are found to show graded microstructures, where the concentration of Fe changes gradually from the surface towards the inside of the specimens. The microstructure of the coated layers consists of mainly tau 2 (Al2FeTi) and alpha Fe. When the coated specimens were subjected to heat cycling test between 293K and 973K, they showed no cracking, no peeling, little oxidation and little microstructure change., CANADIAN INST MINING, METALLURGY AND PETROLEUM
ENVIRONMENT CONSCIOUS MATERIALS - ECOMATERIALS, 2000年,
［査読有り］ Control of lamellar orientation in TiAl base alloy using a combination of heavy extrusion and reactive sinteringT Suzuki; Y Tomota; T Tsujimoto; T Furuyama; K Shibue, Polycrystalline TiAl alloy has been produced using heavy extrusion followed by reactive sintering. Many grains that have a lamellar orientation parallel to the extrusion direction were observed in as-reactive sintered materials. Texture measurements were conducted on the as-extruded and as-reactive sintered materials. A [10 (1) over bar 0] fibre texture was found for Ti in the as-extruded material and for the alpha(2) phase in the as-reactive sintered material. The deformation texture of Ti remained after reactive sintering. Thus, the control of crystal orientation of the elemental Ti powder is an effective method of controlling the lamellar direction of reactive sintered TiAl alloy., TAYLOR & FRANCIS LTD
PHILOSOPHICAL MAGAZINE LETTERS, 1997年06月,
［査読有り］
