2. Materials Development

It is well known that the trade-off relationship exists between strength and ductility in metallic materials. We developed technologies to obtain materials with both high strength and high ductility: innovative steel sheets with tensile strength of 1.5 GPa and elongation of 20% and high-strength innovative 5000 series and 6000 series aluminum alloys with Sc precipitates. For innovative magnesium alloys, we have completed the evaluation of a prototype hermetic fatigue test structure for a full-size (5 m long) high-speed rail car using a flame-retardant magnesium alloy. For innovative titanium alloys, we developed innovative refining and manufacturing processes to reduce production costs. Thermoset carbon fiber reinforced plastic requires heating and curing in a high-temperature autoclave for several hours, resulting in an increase of the production costs and limited use in automotive applications. The LFT-D (Long Fiber Thermoplastics-Direct) process, in which thermoplastic resin and relatively long carbon fiber are mixed and pressed at high speed, was adopted to develop a high productive manufacturing process, and trial prototypes of chassis and floor panels were manufactured on trial. We succeeded in introducing innovative carbon fibers, by developing new precursor compounds to get flame resistant polymer threads for pre-carbonization, and also by developing new microwave carbonization process technology.