Steel Research Group

Steels are the most important structural metallic materials and development of steel science should be necessary for achieving safe, secure, and sustainable social infrastructures. Due to the recent economic and environmental viewpoints, developing high strength steels are being desired more and more. The exhausting natural resources is also an important issue in steel industry. Most of the total domestic consumption of rare metals, such as, chromium, molybdenum, niobium, vanadium, is occupied by steel industry. Accordingly, it is necessary to achieve advanced strengths with high strength / high fracture resistance not by simple addition of alloying elements but by microstructural control. Through precise microstructural and crystallographic characterizations, our group investigates phase transformation and deformation / fracture behaviors of steels. Based on such the fundamental research, we try to propose novel alloy design and microstructure design concepts for developing advanced steels from theoretical background.

Specialized Research Field

Microstructure evolution through phase transformation

Because each of the transformation products in steels exhibit different mechanical properties, steels can cover wide range of strength level by controlling its phase transformation.  The deep understanding of microstructure evolution via phase transformation enables us to improve mechanical properties of steels.  We are studying fundamental aspects of phase transformations in steels, such as martensitic transformation, dynamic ferrite transformation, etc., through various state-of-the-art analytical tools, i.e., scanning / transmission electron microscopy, 3D atom probe, synchrotron radiation X-ray diffraction (SPring-8), and neutron diffraction (J-PARC).

Deformation and fracture behaviors

In general, strength and ductility are trade-off relationship.  In order to achieve metallic materials managing both high strength and large ductility, it is necessary to adequately control plastic deformation behaviors.  Our group is conducting fundamental research to quantitatively understand relationship between plastic deformation behaviors and macroscopic mechanical properties by multi-scale analysis using scanning / transmission electron microscopy, digital image correlation technique, and synchrotron radiation X-ray / neutron diffraction. 
Because susceptibility to brittle fracture increases with an increase in strength level of materials, one of the most serious issues for practical applications of high strength steels is brittle fracture (low temperature embrittlement, hydrogen embrittlement, and so on).  Our group is studying crack initiation and propagation behaviors by scanning / transmission electron microscopy analysis, and trying to correlate them with macroscopic fracture toughness properties by utilizing finite element simulation.  The goals of our group are to elucidate the mechanism of brittle fracture and to propose novel alloy design and microstructure design concepts for developing advanced steels with high fracture resistance from theoretical background.

Group Member

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Steel Research Group
1-2-1 Sengen, Tsukuba, Ibaraki 305-0047, JAPAN
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