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Research paper : Energy savings in transportation systems by weight reduction of their components (M. Sakamoto et al.)−128−Synthesiology - English edition Vol.2 No.2 (2009) some products, and joint development is in progress with automobile parts manufacturers. However, the manufacturing cost is a barrier at present, and basic research must be conducted by returning to the basic principles as soon as possible to overcome this issue, as mentioned in section 3.2.・Plate materialMetal plates can be easily formed into various shapes, and therefore they are basic industrial materials. Normally, they are formed by rolling the metal at room or high temperature between two rollers to make thin plates. Although magnesium alloy plates are highly in demand, rolling is difficult since the material tends to crack. Therefore, it requires more rolling processes compared to aluminum and other metals, and that increases the price. Although there are limitations on size and precision, the plates can be manufactured satisfactorily by hot extrusion. The aforementioned two extrusion companies have easily manufactured plates with thickness of 1 mm or less. It is also confirmed that good properties are shown when the extruded material is rolled afterwards. Here, one advantage of noncombustible alloys is that thin sheets can be manufactured since there are no worries of ignition or oxidation at temperature required for hot rolling, and the rolling company has succeeded in manufacturing products with thickness of 0.1 mm. However, the manufacture process of plates requires several steps and therefore, the cost is a more serious problem than forging. For mass supply of low cost plate materials, more technological developments including development of material with good formability are necessary.・Welded structures using extruded materialsThe structures fabricated by joining plastic formed materials such as forged, plate, or extruded materials are core technologies for various applications to automobiles, railroad vehicles, aircrafts, and other machine structures. Figure 12 is an example of such an application – passenger seats for railroad vehicles. This product cleared the current standard for seats for train cars and is expected to play a role in weight reduction. We presented the product to the Japan Railway Company, and it is under consideration. Even for just one item such as this seat, integrated technology is important since it involves cast, extruded, and plate materials, as well as bending and pressing processes. Joining requires guarantee of reliability through basic joining and fatigue tests. In this example, TIG weldingTerm 5 was used, and fabrication of a welding rod for this process was necessary. Also, in some parts, new surface treatment appropriate for noncombustible alloys was done. This shows that a wide range of technological integration is necessary in actual product development, and feedbacks from universities and public research institutes in the aforementioned R&D network were very important for the investigation of all elemental technologies.6 Remaining issuesTo nurture one material as a core material, extremely wide-ranging technological development from upstream to downstream and the accumulation of technologies are necessary. In that sense, rather than asking what are the remaining issues, we must say we just arrived at the starting line of development. However, we must develop the technology to utilize magnesium as an environment-friendly material for the future. To accomplish this, a wide scope of technological development for the material must be considered from the perspective of life cycle assessment, starting with ore mining, as well as the refining, processing, and recycling technologies, and the social system of cascade recycling. Particularly, the current refining process consumes high quantity of energy as exemplified by titanium and aluminum, and the effort for true energy saving has just begun. Although the potential in Japan for refining technology has advanced remarkably, innovative breakthrough is strongly desired. On the other hand, there are still mountains of issues such as quality assessment technology for molten metal and ingot, low-cost surface treatment technology, highly reliable joining technology, as well as standards for various materials and standardization of the assessment technologies. We hope to solve the above issues, and achieve commercialization of the core materials by employing low environmental load and low cost processes.TerminologyFig. 12 Railroad vehicle seat made of noncombustible magnesium alloy (AMX602).Smelting: The process of working metal in its molten stage. This includes casting where the molten metal is poured into a mold and then hardened, as well as manufacturing of metal blanks for plastic forming. In contrast to smelting, there are methods where metal powder is hardened and formed, as well as plastic forming where metal is deformed into shapes.Cold process and hot process: Differentiation is made according to the temperature range when plastic forming metals. When metal crystal is plastic formed at low temperature such as room Term 1. Term 2.

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