A5047187926- Microstructure and Mechanical Properties of Steels
- Metal Alloys Wear and Properties
- Microstructure and mechanical properties
- Hydrogen embrittlement and corrosion behaviors in metals
- Metallurgy and Material Forming
- Metal and Thin Film Mechanics
- Metal Forming Simulation Techniques
- Fatigue and fracture mechanics
- Advanced materials and composites
- Powder Metallurgy Techniques and Materials
- Corrosion Behavior and Inhibition
- Material Properties and Failure Mechanisms
- Tribology and Wear Analysis
- Magnetic Properties and Applications
- Mechanical stress and fatigue analysis
- Advanced Surface Polishing Techniques
- High-Velocity Impact and Material Behavior
- Metallic Glasses and Amorphous Alloys
- High Temperature Alloys and Creep
- Surface Treatment and Residual Stress
- Fusion materials and technologies
- Engineering Applied Research
- Lubricants and Their Additives
- Non-Destructive Testing Techniques
- Mechanical Failure Analysis and Simulation
National Institute for Materials Science
2015-2024
Institute of Metal Research
2006-2010
NTT (Japan)
2007
The University of Tokyo
1975-2002
Kyushu University
1993-2000
Materials Science & Engineering
1993-2000
Kanagawa University
1993
Tokyo University of Science
1992
Materials are typically ductile at higher temperatures and become brittle lower temperatures. In contrast to the typical ductile-to-brittle transition behavior of body-centered cubic (bcc) steels, we observed an inverse temperature dependence toughness in ultrahigh-strength bcc steel with ultrafine elongated ferrite grain structure that was processed by a thermomechanical treatment without addition large amount alloying element. The enhanced is attributed delamination result crack branching...
Mechanical milling using a high energy planetary ball mill was applied to the powder mixtures of iron, chromium and yttria (Y2O3) (Fe-24mass%Cr-0-15mass%Y2O3) introduce very large strain into iron-base matrix, microstructural changes during mechanical were investigated in relation decomposition behavior Y2O3 particles. more than 36 ks long enough allow alloying iron powders. After ks, ultrafine bcc crystalline grains 10 20 nm formed within Fe-24mass%Cr-15 mass%Y2O3 mixture 15 mass% particles...
The deformation of tempered martensitic structures, namely tempforming treatments, were applied to a 0.6C–2Si–1Cr steel at 500, 600 and 700°C using multi-pass caliber-rolling with an accumulated area reduction 80%. tensile Charpy impact properties investigated make clear the relation between microstructure delamination behavior tempformed (TF) samples. treatments resulted in evolution ultrafine grain structures strong ‹110›//rolling direction (RD) fiber textures fine spheroidized cementite...
Ductile-to-brittle transition (DBT) temperature and brittle fracture stress, σF, are important toughness criteria for structural materials. In this paper, low-carbon steels with an ultrafine elongated grain (UFEG) structure (transverse size 1.2 μm) two ferrite (α)-pearlite sizes 10 µm 18 were prepared. The UFEG steel was fabricated using multipass warm biaxial rolling. tensile tests a cylindrical specimen three-point bending single-edge-notched performed at -196 °C. local stress near the...
The hydrogen embrittlement property of a prototype 1700-MPa-class ultrahigh-strength steel (NIMS17) containing traps was evaluated using slow strain rate test (SSRT) after cathodic precharging, cyclic corrosion (CCT) and atmospheric exposure. content in fractured specimen measured SSRT by thermal desorption spectroscopy (TDS). relationship between fracture stress for the hydrogen-precharged specimens showed that NIMS17 higher, at given content, than conventional AISI 4135 steels with tensile...
Our strategy is to enhance the fracture property of ultra-high-strength low-alloy steels with a yield strength 1.4 GPa or over by arresting propagation brittle cracks in hierarchical, anisotropic, and ultrafine-grained structures. This provides fail-safe design addition suppressing crack initiation. The present article reviews strength, ductility, toughness, delayed resistance ultrafine elongated grain structures processed deformation tempered martensitic at elevated temperatures (referred...
The behavior of work-hardening which occurs during mechanical milling (MM) treatment in metallic powders, and the process recovery recrystallization annealing MM powders were over-viewed showing results obtained by authors using an industrial pure iron powder. Through treatment, stores extremely large strain energy, this marked formation a fine structure with nanocrystalline grains. In case iron, hardness powder can be increased to DPH1024 practice, crystalline grain size is reduced limiting...
(0.2–0.6)%C-2%Si-1%Cr-1%Mo steels were quenched and tempered at 773 K deformed by multi-pass caliber rolling (i.e. warm tempforming) with a reduction of 78%, in order to obtain ultrafine elongated grain (UFEG) structures. The tensile Charpy impact properties the tempformed (TF) investigated determine influence carbon content on toughening UFEG TF samples consisted structures strong <110>//rolling direction (RD) fiber textures. transverse size aspect ratio structure tended reduce as...
Improving the balance of strength and toughness in structural materials is an ongoing challenge. Delamination grain refinement are some methods used to do this. In this paper, two different steels, 0.15% C-0.3% Si-1.5% Mn-Fe 0.4% C-2% Si-1% Cr-1% Mo-Fe (mass %), were prepared. Two steel bars with ultrafine elongated (UFEG) structure fabricated via multipass warm caliber rolling. The UFEG steels characterized by a strong <110>//rolling-direction fiber texture. transverse size, dt, was 1.0 µm...