Invited Lectures

Professor Emeritus, Yokohama National University
Specially Appointed Professor, Osaka University

Professor Hiroshi Fukutomi has been engaged in various research in the fields of ceramics,   metals, and alloys, focusing on microstructure control. He has published more than 100   original papers, which have been highly regarded both domestically and internationally, and   has received various academic awards for his research. As one of leading researchers in the field of materials engineering, he has served as president of The Japan Institute of Metals, director of The Iron and Steel Institute of Japan, and member of the committee of many international conferences. Professor Fukutomi has worked on a wide range of issues, from basic studies to applied fields, and has promoted collaboration not only with academic societies but also with Japanese industry.

Influence of Orientation Distribution in Polycrystalline Materials on Mechanical Properties - Material Development by High Temperature Deformation

It is well known that the mechanical properties of metals and alloys are structure-sensitive. Structure here refers to microstructure and includes factors such as grain size, grain and phase morphology, dislocation structure, precipitates, dispersion particles, phase structure, crystal orientation, and defects.

The development of metallic materials has been conducted through a combination of alloy composition development and microstructure control, and the importance of microstructure control has increased with the global emphasis on SDGs and the need to develop metallic materials that are easily recyclable. Crystal orientation control, that is, texture control, has so far not been emphasized as a development technology for structural materials, but it is expected to develop in the future as a material development technology that does not rely too much on alloying elements. Techniques that combine texture with other elements that have attracted attention so far, such as grain refinement and phase morphology, are also being proposed.

On the other hand, the development of texture or the frequent presence of grains with a particular crystal orientation may impair the properties of the material. Materials that have undergone plastic working will have a more or less biased crystal orientation distribution. Therefore, when understanding damage and destruction of materials, it is also necessary to pay attention to the distribution of crystal orientation. With the development of EBSD, it became possible to investigate the influence of the orientation of individual grains.

The formation mechanism of texture concerning recrystallization and its control techniques are still under discussion. The authors finally introduce that they have developed a new principle for developing texture through high-temperature processing, and have succeeded in controlling the texture of Ti alloys based on this principle through joint research between Yokohama National University and Ostrava University of Technology.