Mazda Motor Corporation, in collaboration with Sumitomo Metal Industries and Aisin Takaoka, claims to be the first automaker to successfully develop vehicle components using 1,800 MPa ultra-high tensile steel for use in CX-5 crossover bumper beams.
The beams fit inside the front and rear bumpers and absorb damage in the event of a collision. The bars are 20% stronger and 4.8kg lighter than previous versions and are a key part of the automaker’s new, lightweight and highly rigid vehicle architecture. The new architecture incorporates a new energy absorbing structure as well as expanded use of high-tensile steel to reduce weight.
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The use of high tensile steel enables vehicle parts to be thinner yet still retain the same degree of high strength. This leads to significant savings in vehicle weight. Reducing the weight of bumper beams is particularly important because, as they are incorporated into the body structure at the farthest point from the vehicle’s centre of gravity, their weight has a considerable effect on dynamic performance and responsiveness. They must also be strong to provide sufficient collision protection. For these reasons, a method of mass-producing parts using stronger steel has been highly sought after.
However, stronger materials are less pliant and therefore absorb less energy in a collision. To overcome this, the automaker conducted extensive research into how bumper beams deform in a crash and created a new design that absorbs energy more efficiently. Additionally, in order to ensure the bumpers provide maximum strength, Mazda collaborated with Futaba Kogyo to optimise the welding techniques and to establish a reliable manufacturing process.
