Theme I: Recent trends on systems resilience to realize both maximum efficiency and operational stability
Chairpersons: N. Fujii (Kobe Univ.), H. Narazaki (Kobe Steel, Ltd.)
In the complex supply chain of the steel industry, it is necessary to develop stable margin assessment, failure risk prediction techniques and system resilience operation to maintain the health of the entire system to the maximum extent possible even in deteriorating conditions, in order to realize "aggressive operation" that minimizes margin and maximizes robustness. In this discussion, we will share the latest developments of the research group that was launched with the aim of building a system model of resilience and supporting human intervention decisions in the process of stability deviation, rather than automation, and discuss related topics.

Theme II: Advanced technologies in steel sheet forming and issues
Chairpersons: T.Kuwabara (Tokyo Univ. of Agriculture and Technology), K. Hayakawa (Shizuoka Univ.)
The improvement of steel sheet forming technology is advancing day by day. As a result of increasing the strength to meet the demand for weight reduction of automobile bodies, it is an urgent issue to improve the accuracy of springback and fracture prediction and to improve the durability of shearing dies. For mild steel sheets, high design of the body shape is required, and advanced shape prediction technology by CAE is required. In this debate, the latest data on the deformation characteristics of steel sheets will be summarized, the latest trends and issues of forming technology will be discussed, and future technological trends will be prospected.

Theme III: Needs for tubes with uneven thickness and their manufacturing and forming techniques 3
Chairpersons: T.Kuwabara (Tokyo Univ. of Agriculture and Technology), T. Furushima (The Univ. of Tokyo)
There is a demand in the industry for steel tubes with uneven thickness, in which excess tube thickness is reduced as with tailored sheet blanks, to further reduce the weight of transportation equipment such as automobiles. Uneven thickness tubes have locally thickened sections at which the thickness is to be reduced in the second forming process. Another example of uneven thickness tube is that having the thickened ends for pre-reinforced tube joints. In addition, these uneven thickness tubes are highly applicable to non-transport equipment. This session aims to discuss the needs of tubes with uneven thickness and their manufacturing and forming technologies.

Theme IV: Elucidation of bio-corrosion mechanism and development of diagnosis / deterrence technology for bio-corrosion
Chairperson: Y. Miyano (Akita Univ.)
The mechanism of MIC（microbiologically influenced corrosion）, the microorganisms and the effects of microorganisms that cause MIC are still unknown. There are many issues that we must address, then materials research is expected to make a significant contribution to the development of technologies for controlling and preventing microbial corrosion. In this session, we would like to have an active discussion on some researches on empirical elucidation of MIC and the interaction between metals and microbes from various academic fields such as materials engineering, microbiology, and environmental science.

Theme V: Importance of plasticity-driven fracture and its required analytical techniques
Chairperson: M.Koyama (Tohoku Univ.)
There are still many uncertainties in the plasticity evolution of steels. In particular, the micro-plasticity behavior of advanced steels, which contain complex microstructures, has been the hottest research topic. The plasticity evolution induces damage in the late deformation stage, which causes a “plasticity-driven” fracture phenomenon. Specifically, the microstructural plasticity results in an increasing of local stress and formation of microstructures that act as an origin of the fracture. These plasticity effects cause crack initiation. It is noteworthy that fracture does not occur immediately after the crack initiation when the material has a significant ductility. The subsequent straining results in crack tip deformation and coalescence of multiple cracks, which cause crack growth. When the effects of specimen shape changes, crack-tip stress field, and critical damage size / crack length are considered, the mechanics-based understanding are indispensably required. Understandings of these plasticity-driven fracture phenomena and their processes are important not only for the typical ductile fracture also for other practically important failure problems such as fatigue failure, hydrogen embrittlement, blue brittleness. The present discussion session aims at sharing the practical demands of understanding the plasticity effects on the fracture and associated advanced techniques for characterizing/evaluating the failure behavior, which is believed to become a common property in the steel research society.