Site: Tohoku University Division of Foundry Engineering 980-77 Sendai, Japan Date Visited: January 9, 1996 WTEC Attendees: T.S. Piwonka (report author), H.W. Hayden Hosts: Dr. Eisuke Niyama, Professor Dr. Koichi Anzai, Associate Professor
Tohoku University was founded in 1907 as one of seven imperial universities in Japan. Today it has an enrollment of 3000 students and graduates 1000 each year. In the college of engineering there are 1000 undergraduate students and 600 graduate students annually. The college has 17 departments, with 170 full professors, 19 of whom are in materials-related departments. The college operates on the "small chair system," which means that a laboratory operates with one full professor, one associate professor, and one or two research associates, and occasionally a post-doctoral student. Half the graduate students are foreign (mostly Chinese, Korean, and Thai). The university is having difficulty attracting students to study in materials engineering courses, as few Japanese are interested in the subject.
Tohoku has the only laboratory specifically designated for "Foundry Engineering" in any national university in Japan and is highly regarded by the foundry industry. At present there are eight undergraduates, seven masters degree students, four Ph.D. students, and one "research student." There are also four visiting researchers (three from China) and two technicians. The foundry laboratory is an adequate older lab, which contains, in addition to normal foundry equipment, a water analog die casting machine, and a vacuum-pressure titanium furnace (with which a student whose father owns a titanium foundry is working).
Graduate students are not paid by research projects but are normally supported by their parents (which is one reason that they leave the university earlier than the faculty would like). The professor too is paid entirely from university funds. The WTEC team learned during another visit that industrial support for R&D at universities may have been limited or restricted at one time. This probably is no longer be the case, since Prof. Niyama reported considerable industry support for his research. Prof. Niyama's laboratory has a fixed budget of ¥4 million from the university and raises about ¥13 million from research projects. This money goes for travel, materials, and equipment, and is spread among the projects (even though it may have been raised primarily for a specific project).
Professor Niyama's lab has a research policy that includes the following:
In the future he hopes to continue his ties to industry, increase international cooperation, and widen the application of simulation techniques to other fields.
The highlight of Prof. Niyama's research at present is a solidification simulation package, called STEFAN. This is a three-dimensional heat and fluid flow package (FDM-based), which features simple treatment of complicated shapes, quick and reliable calculation of flow with free surfaces, and flexible choices of hardware. The software is not sold, but distribution is limited to the sponsors of the project, which are 30 companies (a majority of which are die casters). Development began four years ago. The source code is open to allow changes and additions. Yonsei University (Korea) and Tsinghua University (China) are also cooperating on development of the code, by sending visiting scholars to Tohoku. STEFAN has not yet been benchmarked against the popular western solidification simulation codes Procast© and Magmasoft©. STEFAN at present does not include any modeling of microstructure or use of expert systems to simplify analysis. The program was demonstrated for us and is quite capable of providing good simulation of fluid flow during mold filling and solidification.
Another area of research is focused on thin-section castings. One of the projects under this area is the fluidity of alloys. Present work is looking at solidification structure zones formed during flow in cast iron and hypereutectic Al-Si. One of the findings so far is that hypereutectic Al-Si (16.8% Si) is more fluid than eutectic Al-Si. Prof. Niyama also has measured substantial supercooling (200°C) in the tip of fluidity streams if the metal is kept clean. Another project is an investigation of the casting surface, using the "droplet method," in which a large drop of molten metal is dropped on a chilled surface, and the shape of the resulting pancake determined. Initial results show that the surfaces of drops of pure metals in contact with the chilled surface are convex, while alloys solidify with either a convex or a concave surface. Another method is to study the formation of wrinkles on the surface of metal solidified on a chill which is dipped into molten metal.
Other current projects include water modeling of die and permanent mold filling to optimize gate design, studies of the mechanism of segregation in aluminum squeeze casting, and the fluidity, shrinkage and mold reaction of titanium alloys in precision casting. Three projects are focused specifically on cast iron. One deals with the mechanism of shrinkage formation in cast iron, particularly the effect of the semisolid skeleton on shrinkage, following Lesoult's methodology, in order to cut down computational time. A second is comparing "successive austempering" vs. "direct austempering" of ductile iron, and a third is investigating nodularization of ductile iron by the inmold process, looking at reaction chamber design and inoculant composition.
Prof. Niyama indicated that progress should be expected in all areas of casting technology. He does not foresee wholesale replacement of ferrous castings in automotive applications by non-ferrous castings. He suggested consulting the Japan Foundry Engineering Society journal in December of each year to learn what Japanese foundrymen are most interested in. The December issue is a special issue focusing on one subject of interest to the industry. Past issues have had the following topics: