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As part of Mazda’s efforts to reduce vehicle mass (part of its SKYACTIV Technology initiative), it has collaborated with Sumitomo Metal Industries (sumitomometals.co.jp/e/) and Aisin Takaoka (at-takaoka.co.jp/English) for the development of what is claimed to be the first components produced with 1,800 MPa ultra-high tensile strength steel.
The steel is being used to produce bumper beams for the front and rear bumpers of the 2013 CX-5 crossover.
The bumper bars are 20% stronger and 10.6 lb. lighter than the components that would otherwise be used. That’s because they’re able to make the parts thinner without losing any strength, or in this case, actually tailoring the design to increase the strength. One of the issues related to materials like this ultra-high strength steel is that they tend to be less formable, and so to assure that the bumper beams would absorb crash energy (a collision can be loosely considered analogous to uncontrolled stamping), they had to create the structure for the required crash energy management.
Also, welding can be a challenge, so Mazda worked with Futaba Kogyo (y-futaba.co.jp/eng/index.htm) to optimize the welding techniques so that they’ll have a reliable welding process for production of the CX-5 bumper beams.
It is worth noting that because the bumper beams are located far from the vehicle’s center of gravity, they have an effect on the dynamics of the vehicle. Because Mazda’s—even crossovers—are meant to have “Zoom-Zoom” performance, it was of particular importance to create parts that are light for spirited driving but strong for safety.