Yusuke Onuki

Yusuke Onuki
Tokyo Denki University · Department of Advanced Machinery Engineering

D. Eng.

About

71
Publications
6,247
Reads
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300
Citations
Additional affiliations
May 2014 - December 2014
Tohoku University
Position
  • PostDoc Position
April 2013 - March 2014
University of Saskatchewan
Position
  • PostDoc Position
Education
April 2010 - March 2013
Yokohama National University
Field of study
  • Metallurgical science

Publications

Publications (71)
Article
Strengthening of biomedical Co–Cr–Mo alloys has been explored via thermomechanical processing for enhancing the durability of their biomedical applications. However, the effects of cold and hot deformation on the cellular activity continue to be unclear. In this study, we prepared Co–Cr–Mo alloy rods via cold swaging and hot-caliber rolling and stu...
Article
Full-text available
Retained austenite is a key feature used to realize the transformation-induced plasticity in bainitic high strength steels. In this study, the authors focused on the formation of metastable austenite in Fe-0.61C-1.9Si-0.98Mn (mass%) during isothermal heating processes using in situ neutron diffraction techniques. Quantitative discussion of carbon p...
Article
Full-text available
Ti–6Al–4V alloys prepared via electron beam powder bed fusion (EB-PBF) generally exhibit a hierarchical microstructure consisting of columnar β-grains, an acicular α-matrix, and nanoscale β-precipitates at α-lath interfaces. In this study, we performed time-of-flight neutron diffraction measurements to investigate the texture and volume fraction of...
Article
This report demonstrates, for the first time, structural evolution during nano structuring by severe plastic deformation and comprehensive structural relaxation upon heating in an additive‐manufactured 316L stainless steel by applying the characterization techniques of X‐ray diffraction and in‐situ neutron diffraction analyses. This study by Megumi...
Article
Full-text available
A multifunctional NiTi alloy with Invar (dimension-invariant), Elinvar (elastic modulus-invariant) and Rinvar (resistivity-invariant) properties over the temperature range from 125 K to 375 K is fabricated through cold rolling of 60% thickness reduction. The underlying microstructure of such multifunctional NiTi alloy mainly consists of B2 and B19′...
Article
The transformation and stabilization behaviors of the austenite (γ) phase during bainite transformation in the early stages of austempering treatment of low-alloy transformation-induced plasticity-aided bainitic ferrite (TBF) steel were investigated by in-situ neutron diffraction measurement and microstructure observation. Neutron diffraction peak...
Article
Full-text available
Middle-carbon martensite steels are vital materials for mechanical components and their mechanical properties have attracted significant interest. However, the decrease in the elastic limit of the as-quenched materials is one of the remaining puzzles. Herein, we quantitatively characterized the dislocation density and its structure in the as-quench...
Article
The present report conducts lab-scale X-ray diffraction and in-situ heating neutron diffraction analyses for evaluating the structural changes at post-printing nanostructuring and structural relaxation upon heating, respectively, in an additive-manufactured (AM) 316L stainless steel. The nanostructured AM steel after nanostructuring by high-pressur...
Article
Full-text available
Texture memory is a phenomenon in which retention of initial textures occurs after a complete cycle of forward and backward transformations, and it occurs in various phase-transforming materials including cubic and hexagonal metals such as steels and Ti and Zr alloys. Texture memory is known to be caused by the phenomena called variant selection, i...
Article
The CoCrFeMnNi high entropy alloys (HEAs) performs large work strengthening with excellent deformability. The work strengthening and deformation mechanism are facilitated by dislocation activities and dislocation accumulation. In this study, the dislocation density and microstructure of the CoCrFeMnNi HEA were characterized by the neutron line prof...
Article
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Cu-doped martensitic steels (Fe-(13, 16)Cr-3W-2Cu-1C) (mass%) with multiple carbide precipitates were prepared at different quenching temperatures, and their corrosion behaviours were examined by measuring the weight loss during immersion in a 0.5 M H 2 SO 4 solution. Lower weight losses and corrosion rates were obtained for the alloy samples prepa...
Article
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Manipulating macroscopic thermal expansion (TE) through microstructure engineering is emerging as a new research topic of shape memory alloys (SMAs). Here, we perform a modelling-and-experiment combined study to design and tune the coefficient of TE (CTE) of polycrystalline martensitic SMAs based on reorientation deformation. Using Landau thermodyn...
Article
Full-text available
Many established, but also potential future applications of NiTi-based shape memory alloys (SMA) in biomedical devices and solid-state refrigeration require long fatigue life with 107–109 duty cycles1,2. However, improving the fatigue resistance of NiTi often compromises other mechanical and functional properties3,4. Existing efforts to improve the...
Article
Precipitation-hardened ferritic stainless steels are used for soft magnetic actuators of engines, as these steels exhibit high strength and soft magnetic properties. These ferritic stainless steels are hardened by nanoscale precipitates formed during an aging process after solution treatment. Furthermore, texture control of these steels is required...
Article
Shear deformation is imposed on materials by several advanced techniques for microstructural and textural control. Shear texture evolved during deformation tends to remain after subsequent annealing. Texture evolutions with shear deformation and subsequent annealing in aluminum and Al-3mass%Mg alloy rolled sheets have been investigated by neutron d...
Article
Texture memory of Si-Mn and ODS steels has been explored via in situ neutron time-of-flight and synchrotron high-energy X-ray diffractions as well as texture prediction by the double Kurdjumov-Sachs relation. The two steels exhibited very different behaviors of the texture memory. Three behaviors were observed: (1) for Si-Mn steel, the moderate ini...
Article
Full-text available
Herein, the texture developments of γ austenite, ε martensite, and α’ martensite during the tensile deformation of SUS 304 stainless steel were observed by using the in situ neutron diffraction technique. Combined with the microstructure and local orientations measured by electron backscattered diffraction (EBSD), the mechanisms involved in the def...
Article
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Shape memory alloy (SMA) sheets processed via unidirectional rolling (UniR) exhibit macroscopic low thermal expansion (TE) over a wide temperature span but only along a certain direction. Here, we use controlled cross rolling (CroR) to achieve in-plane low coefficients of TE (CTEs) of polycrystalline NiTi sheets. It is shown that the in-plane CTEs...
Article
The authors have developed the in situ neutron diffraction technique focusing on bainite transformation during austempering. Thanks to the features of time-of-flight type neutron diffraction, textures, phase fractions and lattice parameters can be simultaneously measured at high temperature. In this paper, the design of experimental equipment and a...
Article
Relationship between dislocation multiplication and work hardening of tensile-deformed Cu-Zn alloys with different grain sizes was investigated. X-ray diffraction line-profile analysis was employed to evaluate dislocation parameters. It was confirmed that dislocation multiplication was enhanced with a decrease in the grain sizes. This was mainly ca...
Article
Full-text available
Multiplication and rearrangement of dislocations in face-centered cubic (FCC) metals during tensile deformation are affected by grain size, stacking fault energy (SFE), and solute elements. X-ray diffraction (XRD) line-profile analysis can evaluate the dislocation density (ρ) and dislocation arrangement (M) from the strength of the interaction betw...
Article
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We tailor the temperature dependence of elastic modulus (TDEM) of polycrystalline NiTi plates by cold rolling up to 60% thickness reduction. In-plane Elinvar property is obtained with a low elastic modulus temperature coefficient of 6.0 × 10⁻⁵ K⁻¹ over a temperature range of 192 K. The microstructure mainly consists of approximately equal volume fr...
Article
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304 stainless steel is one of the most common stainless steels due to its excellent corrosion resistance and mechanical properties. Typically, a good balance between ductility and strength derives from deformation-induced martensite transformation (DIMT), but this mechanism has not been fully explained. In this study, we conducted in situ neutron d...
Article
Surface effect-induced phase transformation heat treatment is performed on cold-rolled commercial pure titanium sheet to change and control the transformation texture. The results show that the type of final transformation texture changes from the texture memory effect type texture of TD-split basal to the surface effect type texture of 〈11−20〉//ND...
Article
Full-text available
By using a steel with standardized chemical composition and conventional manufacturing processes for flat-rolled steel strip, a 1500 MPa class stainless steel sheet, whose product of yield strength (YS) and total elongation (El) exceeds 30000 MPa%, was developed and its mass production was established. Besides the excellent YS–El balance, the devel...
Article
The demand for a reliable and quantitative method to determine phase fractions has been increasing due to the developments of multi-phase materials, such as TRIP steels. The authors conducted a mutual verification between the two methods for phase fraction analysis, the saturation magnetization measurement and the newly developed neutron diffractio...
Article
In order to reveal the behaviors of two kinds of martensites (ε-M and α′-M) transformation during TRIP and reversion process and to separate transformation textures from rolling textures during the TRIP process, the phase transformation and texture evolution during cold rolling and the subsequent heating in high manganese TRIP steel were investigat...
Article
Full-text available
By using a steel with standardized chemical composition and conventional manufacturing processes for flat-rolled steel strip, a 1,500 MPa class stainless steel sheet whose product of yield strength (YS) and total elongation (El) exceeds 30,000 MPa% was developed and its mass production has been established.Besides the excellent YS-El balance, the d...
Article
An in situ neutron diffraction experiment during austempering of low-alloyed transformation-induced plasticity steel, Fe-1.48Si-1.52Mn-0.15C, in wt pct was conducted. In this study, time-of-flight neutron diffractometer with a large detector coverage, iMATERIA at J-PARC MLF, was employed. The phase fraction and carbon concentration in austenite cou...
Article
In order to study the plastic deformation mechanism of AZ31 magnesium alloy, in situ texture measurement during uniaxial tensile deformation is conducted by using neutron diffraction. The specimen is prepared from a rolled sheet so that the deformation axis is parallel to the rolling direction. By increasing strain, the alignment of <10-10> along t...
Article
The overview of the recent works by the author at iMATERIA, BL20 of J-PARC MLF is introduced. From the viewpoint of microstructural control, the author and coworkers have expanded the availability of iMATERIA to metallurgical studies. The authors have established the measurement/analysis scheme for crystallographic textures and phase fractions in m...
Book
Full-text available
鉄鋼材料に代表される金属のミクロ組織に対し,放射光,中性子線の量子ビームを用いた 新たなアプローチが可能になる.放射光の高輝度特性を活かしたマイクロ領域測定や高温そ の場測定により,構造材内部の転位の分布,転位の回復現象の追跡が可能となる.また,中 性子線はバルク平均情報の特徴を活かすことで,複相鋼の強化機構メカニズムが詳細に考察 できる.これら解析事例を原理とともに紹介する.
Article
Relationship between phase transformation and dislocation evolution of Fe-Mn-Si-Cr shape memory alloy upon tensile deformation and subsequent annealing treatment was investigated. Neutron diffraction and electron backscatter diffraction (EBSD) measurements were carried out to evaluate dislocation density and phase transformation. Reasonable phase f...
Article
Full-text available
The authors have developed the simultaneous measurement scheme for texture and phase fraction by using the Time-Of-Flight (TOF) neutron diffractometer, iMATERIA at J-PARC MLF, Japan. The Rietveld texture analysis (RTA) was applied for the data analysis method, which has been developed mainly at HIPPO diffractometer at LANSCE, USA. Because of the di...
Article
Full-text available
Co–Cr alloys have been used in biomedical purposes such as stents and artificial hip joints. However, the difficulty of plastic deformation limits the application of the alloys. During the deformation, Co–Cr alloys often exhibit strain-induced martensitic transformation (SIMT), which is a possible reason for the low formability. The distinct increa...
Article
Full-text available
To investigate the characteristics of dislocation evolution in ferritic and austenitic stainless steels under tensile deformation, neutron diffraction line-profile analysis was carried out. The austenitic steel exhibited higher work hardening than the ferritic steel. The difference in the work hardening ability between the two steels was explained...
Article
We carried out in situ tri-axial magnetostriction analysis for cube-oriented Fe-18%Ga single crystal by X-ray diffraction measurement under magnetic field. Periodic change in tri-axial magnetostriction with applied magnetic field direction was clearly observed. However, those values in [100] and [010] directions were not equivalent. Theoretical cal...
Article
Full-text available
The accuracy of the phase fraction determined by time-of-flight neutron diffraction measurement at iMATERIA was verified by preparing model samples consisting of laminations of ferritic and austenitic stainless-steel sheets. Rietveld texture analysis, based on 132 diffractograms, was employed as the analysis method. The analyzed volume fractions of...
Article
Fe-Ga alloys show large magnetostriction, which strongly depends on crystal orientation. This phenomenon is associated to some degree with large elastic anisotropy. In this study, white X-ray diffraction with micro-beam synchrotron radiation was used to evaluate the microscopic stresses evolved in a polycrystalline Fe-Ga alloy under tensile loading...
Article
Texture is an important property especially for metallic materials having hexagonal close-packed crystal structure. In order to understand the overall property or change in the microstructure of materials, neutron diffraction is a powerful tool of investigation. In this study, we attempt to measure the textures of Ti­–6Al–­4V (mass%) alloy by using...
Article
Full-text available
The texture control of Fe–Ga solid solution alloy is examined by high temperature deformation, based on the previously suggested mechanism of high temperature deformation texture formation, “preferential dynamic grain growth (PDGG)”. As the result of uniaxial compression deformation of Fe-15 mol% Ga alloy at 1173 K, sharp alignment of <001> along t...
Article
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We investigated the effect of the relationship between the scattering vector of neutron diffraction and the sample direction processed by cold-rolling on line-profile analysis. It was revealed that dislocation parameters became unstable when using a diffraction profile at the scattering vector parallel to the rolling direction. This is probably due...
Article
The authors measured texture change during uniaxial tensile deformation of extruded bar of AZ31 magnesium alloy by time-of-flight neutron diffraction and EBSD (electron backscatter diffraction). Texture measurement by neutron diffraction revealed the transition of tensile axis distribution in overall gauge volume during the deformation. The concent...
Article
We carried out in situ x-ray diffraction measurements of magnetostriction in an Fe-18at%Ga alloy single crystal under magnetic fields. The sample studied here was a Goss-oriented square plate (dimensions: 10 mm × 10 mm × 1 mm height) cutting from as-grown single crystal ingot produced by the Czochralski method. In-plain magnetic fields were applied...
Article
Full-text available
The authors have developed the texture measurement system at iMATERIA, which is the neutron diffractometers built in Materials and Life Science Experimental Facility (MLF) at J-PARC, Japan. The high flux of the incident beam and Time-Of-Flight method enabled the complete texture measurement within several minutes in case of steels. Since the neutro...
Article
Full-text available
A rapid texture measurement system has been developed on the time-of-flight neutron diffractometer iMATERIA (beamline BL20, MLF/J-PARC, Japan). Quantitative Rietveld texture analysis with a neutron beam exposure of several minutes without sample rotation was investigated using a duplex stainless steel, and the minimum number of diffraction spectra...
Article
A newly developed, austenitic lightweight steel, containing a low-density element, Al, exhibits tensile elongation up to 50% as well as high ultimate-tensile stress (tensile fracture at 1800 MPa) without necking behavior. Electron backscatter diffraction analysis is carried out to investigate the orientation dependence of the martensitic transforma...
Article
The local stress state developed during the elastic deformation of polycrystalline Fe-17mol%Ga was measured by synchrotron white X-ray radiation, and the heterogeneity of the elastic deformation resulting from the pronounced elastic anisotropy of the FeeGa alloy system was examined. Tensile loading generated local stresses perpendicular to the tens...
Article
We have investigated anisotropy behavior of coercivity and scaling law for nano-scale ferromagnetic phases embedded in a paramagnetic matrix of an austenitic stainless steel. Small ferromagnetic martensites are induced by uniaxial tensile deformation. A scaling-law relationship between the hysteresis loss and remanence, with a power law exponent of...
Article
X-ray diffraction (XRD) and electron microprobe microanalysis (EPMA) were used for characterizing the structure and composition of surface layers formed on austenitic Fe-Mn-Si shape memory alloys under vacuum. The XRD results demonstrated that during annealing, face centered cubic austenite is transformed to hexagonal close packed martensite on the...
Article
Full-text available
High speed rolling is recognized as the process that can produce sheets of magnesium alloys having RD-split basal texture without or with minimum preheating. However, the mechanism of the texture formation during high speed rolling has not been fully clarified yet. In this study, conventional AZ31 and a rare earth - yttrium added alloy, WE43 were r...
Conference Paper
Full-text available
A single crystal of the Fe-6 at% Co-15 at% Ga ternary alloy was successfully grown by the Czochralski method. The as-grown ingot with the <100> orientation parallel to the pull-up direction was about 17 mm in maximum diameter and about 55 mm in length. The magnetostriction constant in the <100> orientation λ100 of the single crystal specimen was ab...
Article
抄録 We have performed high-sensitivity magnetic measurements for tensile-deformed SUS304-type austenitic stainless steel to elucidate a relationship between morphology of martensite particles and structure-sensitive magnetic hysteresis properties. A monotonic increase of the volume fraction of martensite phase up to 14.3% through strain-induced mart...
Article
It is known that magnesium alloys can be rolled up to a large thickness reduction and develop a unique texture when the rolling speed is high (>1000 m/min). In order to understand the texture formation mechanism during high-strain-rate deformation, high-speed rolling of AZ31 magnesium alloy samples having different initial textures was conducted. T...
Article
In order to clarify the effect of solutes on texture formation during high-temperature deformation of BCC solid solution alloys, the texture and microstructure formations in Fe-3.1mass%Si (Fe-Si) and Fe-3.2mass%Si-0.12mass%P (Fe-Si-P) during high-temperature uniaxial compression deformation are studied. The analysis of true stress-true strain curve...
Article
A new mechanism of texture evolution, named “preferential dynamic grain growth mechanism”, is examined experimentally by high-temperature plane-strain compression deformation of Fe–3.0 mass% Si alloy. The proposed mechanism is based on preferential growth of the orientations having low Taylor factors and stability against deformation. According to...