Theme I: Recent trends on systems resilience to realize both maximum efficiency and operational stability
Chairpersons: N.Fujii (Kobe Univ.), H. Narazaki (Kobe Steel)
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: Area-sensing-based condition monitoring of facilities in steelworks
Chairperson: I.Ishii (Hiroshima Univ.)
Responding the growing attention to the advanced area sensing based on imaging technologies for abnormality diagnoses of wide variety of infrastructural facilities in the steel works, research group "Facilities in the steel works health monitoring based on area sensing technologies has been carried out since 2019. This session aims to discuss the results of the research group and the perspective in the future.

Theme III: Human-system shared control realizing high efficient and stable rolling
Chairpersons: A.Kitamura (Yamato Univ.), M.Kishi (Nippon Steel)
Shared control based on the trust of people and systems is being expanded into the field of autonomous driving of automobiles. In this research group, in collaboration with the division of processing for quality products, we have been studying shared control through cooperation between control systems and humans, targeting the control of tandem cold mills. In this discussion session, we report on the research results of a rolling shared control system consisting of a rolling simulator equipped with a high-precision rolling model, a model related to the intervention of a rolling operator, a new thickness control system, and an interface for displaying them.

Theme IV: Application of data science technology to rolling and processing lines
Chairpersons: Y.Maeda (Kobe steel), M. Kishi (Nippon Steel), Y.Matsubara (JFE Steel)
Data science technologies using big data, including advanced learning, recognition, and prediction methods, have made great advance. It has been reported to be applied data science in various fields to the steel production process. In this session, we will discuss examples of data science application to rolling and processing lines and explore future technological trends.

Theme V: Current status and future prospects toward understanding microstructure and properties of hot-dip galvanized/aluminized coatings
Chairpersons: N.Takata (Nagoya Univ.), H. Takebayashi (Nippon Steel), M.Koba (JFE Steel), R. Otomo (Kobe Steel), K. Ishii (Nippon Steel)
Hot-dip galvannealed (GA) and hot-dip galvanized (GI) steel sheets exhibited superior corrosion resistance and hot-dip aluminized steel sheets offer heat-resistance properties as well. Such surface-treated steel sheets are used for various structural members. In recent, hot-working processes as well as cold-working have been applied to high-strength galvanized or aluminized steel sheets to form complex shapes, whereby hot-dip coatings with multi-functions are being required. Herein, we will review the current understanding of the structure and properties of the hot-dip coatings and discuss the future prospects for understanding the structural factors that contribute to various functionalities.

Theme VI: Relation between microstructure and heterogeneous plastic deformation behavior in high strength steels
Chairperson: T.Tsuchiyama (Kyushu Univ.)
It is known that multi-phased high strength steels such as DP steel and TRIP steel exhibit heterogeneous stress/strain concentration due to the second-phases; martensite, bainite, retained austenite, precipitates, etc. and they influence the work hardening and fracture behaviors of the material. In addition, even martensitic steel, which consists of a single-phase, has been revealed to show heterogeneous deformation owing to the hierarchical substructure, and it attracts interest in terms of the macroscopic properties. In this discussion, the relationship between the heterogeneous yielding and work hardening behavior in the early stage as well as the correlation between local deformation and fracture in the late stage of tensile and fatigue tests will be focused in order to obtain a microstructure control guideline for further improving the mechanical properties of high strength steels. Then we will clarify the relationship between the microstructure and the heterogeneous plastic deformation behavior by experimental analysis methods. In addition, we will review the recent development of prediction and mechanism elucidation of heterogeneous deformation and fracture by computational engineering methods.

Theme VII: Investigation of bio-corrosion of structural materials --diagnosis and analysis--II
Chairperson: Y.Miyano (Akita Univ.)
Proposal of new experimental method on visualization of biofilm formation and corrosion progress of metal surface, accumulation of new findings concerning microorganisms and their metabolite involved in bio-corrosion, and elucidation of bio-corrosion mechanism or development of counter measures / mitigation technology for bio-corrosion are considered to be the themes that contain important research topic of material science. In this discussion session, researches from various field such as materials science, microbiology, and environmental chemistry will be presented and discussed.