Vol.2 No.2 2009

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Research paper : Energy savings in transportation systems by weight reduction of their components (M. Sakamoto et al.)−125−Synthesiology - English edition Vol.2 No.2 (2009) processing method during the hot processTerm 2. The network-form aluminum-calcium intermetallic compound in the grain boundary is crushed finely in the direction of extrusion. The crystal grain of the metal matrix becomes smaller by the recrystallization effect, and the overall structure becomes extremely fine (Fig. 5b). The strength and elongation properties increase significantly. Figure 6 shows the mechanical property of the AMX602 alloy. In case of the extruded materials, the room temperature elongation improved to the level of over 20 % in materials that underwent T4 treatmentTerm3 after hot extrusion. This shows that a material with good balance of strength and elongation can be obtained if the plastic forming of noncombustible alloys is done optimally.Important plastic forming technology includes forging and rolling. Along with product development by hot extrusion, it is necessary to develop a manufacturing technology for forging and rolling using the extruded material as a starting material. Also, the research is in progress for direct casting technique from low cost continuously casted material where the solidification structure is finely controlled. For plate material, composition and structure with excellent cold forming property is being discovered as a result of basic research, and it is entering the development phase for low-cost mass-production technology. Also, further basic research is necessary to compensate for the lack of alloy types for magnesium alloys, particularly for high strength and heat resistant materials.To realize this alloy as a structural material, reliability assessment is important. Figure 7 is an example of the endurance strength assessment by rotary bending of extruded noncombustible alloy AMX602. The characteristic of this material is its clear endurance limit. It is also known to have a lower notch sensitivity compared to aluminum alloys[2]-[4], and can be used readily as a structural material. However, all fractures start at the inclusion initiation pointTerm 4, and a clean manufacturing technology of high quality material is extremely important[2].3.3 Recycling technologyAs a guideline of material selection for the user, high recyclability is recently becoming important. Recyclability is an important property linked directly to manufacturing cost. As part of recycling research, an in-house recycling technology during smelting is being developed by the foundries, and the current refining level is recycled material use of 50 % or more. An example of mechanical pulverization in the atmosphere is shown in Fig. 8, as a case investigating the safety when used as an automobile component to be shredder treated later and the usability of the material after shredder treatment. The photograph shows the particle of sieve gauge of under 38 m, and this indicates that mechanical pulverization can be accomplished safely. To study the use of such pulverized particles, the adsorption property of arsenic, boron, zinc, and chromium in wastewater were investigated, and magnesium hydroxides were demonstrated to be powerful adsorbents[5]-[7].4 Industry-academia-government collaboration scheme for product realizationTo send out a new material into the world, a clear vision and a scenario for its realization are necessary, after carefully looking at the overall picture of the technology the new material may promote. The noncombustible magnesium alloy is not flammable, so it can be developed in the same manner as ordinary metal materials. However, since it is similar but different from the existing aluminum alloys, it is necessary to prepare the comprehensive technological data and processing systems as in other metal materials. Fig. 6 Mechanical property of noncombustible magnesium alloy (AMX602).Fig. 8 Crushed particles of noncombustible magnesium alloy (AMX602) (sieve gauge 38 m).40001002003000510152025Extrusion/T4ExtrudedmaterialCasting/T4CastingmaterialTensile strength0.2% Proof stressElongationElongation / %Tensile strength, 0.2% Proof stress / MPaFig. 7 Endurance strength assessment of noncombustible magnesium alloy (AMX602).Number of tests to failure, NfStress amplitude, σa (MPa)1041081071061055010015020015KU1000x10.0 µm012915KU5000x2.00 µm0130

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