In many ways, a vehicle can be compared to the human body. Like the body, vehicles are made up of a variety of different components and systems working together to make one cohesive unit. Just as an engine can be likened to a heart, the frame can be compared to the bones. The body of the Elio is made up of steel, and today’s Momentum will take an in-depth look at the materials that make up the frame.
Our engineering team has developed the design of the vehicle utilizing existing steel materials for optimum manufacturability and structural integrity. Our team focused on utilizing materials that are readily available, easily manufactured, and lightweight, while keeping in mind our target of 90% utilization of North American content. We have designed a non-coated steel unibody with conventional and high strength steels to provide occupant safety.
Here is a chart that breaks down the various steels we will be using:
CR2, CR3, and CR4
All three CR (Cold Reduction) steels are used because they enhance strength and formability. Finishing mills roll cold coils of pickled hot-rolled sheet to make the steel thinner, smoother, and stronger by applying pressure rather than heat. Stands of rolls in a cold-reduction mill are set very close together and press a sheet of steel from one-quarter inch thick into less than an eighth of an inch, while more than doubling its length. CR applies to cold-reduced carbon steel sheet of structural quality in grades CR220, CR250, CR320, and CR420, usually without the use of micro-alloying elements. The product is intended for structures that include bolting, riveting, and welding. It is generally used in the delivered condition for fabricating purposes, such as bending, forming, and welding. In total, CR steel makes up 41% of our structure.
Steels in the HSLA (High Strength Low Alloy) range are hardened by a combination of precipitation and grain size refining, resulting in high strength with low alloy content. This enhances weldability and choice of coatings since these steels exhibit neither weld zone softening nor grain coarsening. These grades are particularly suitable for structural components such as suspension systems, chassis, and reinforcement parts. For their respective yield strength levels, these steels all exhibit excellent cold forming and low-temperature brittle fracture strength (starting at grade 320). The entire range of HSLA steels offers good fatigue strength (suspension arm, shock tower) and impact strength (longitudinal beams, cross members, reinforcements, etc.). Because of their mechanical strength, the weight of reinforcement and structural components can be reduced. The HSLA range of products is available in hot and cold rolled grades. The various grades are identified by their yield strength. HSLA steel makes up 59% of our structure.
Just as strong bones are important to a healthy body, a strong frame is necessary for a safe vehicle. The materials that make up the Elio’s frame will make for a safe vehicle while also fitting into the Elio Motors mission.