Magnesium, Exotics and More: Mixed Materials Drive Auto Design

Today’s Ride Is Faster, Lighter, Cleaner, Better

Back when. . .cars were made largely with conventional steel (heavy), outsize details (e.g. tail fins–again, heavy), lots of chrome, big grilles and big headlights. That was then. . .today is lighter, more aerodynamic, more fuel-efficient vehicles, with designers and engineers paying attention to every component and to which manufacturing material will make it best and best-performing. Today’s cars, from wheels to roof, are an amalgam of lightweight metals (magnesium, aluminum, titanium) and their alloys, carbon fiber, high-strength steel, and other materials. The formulae are designed to provide sleeker, lighter products with better mechanical properties and corrosion resistance, and that will use considerably less fuel. 

Magnesium is the lightest known metal and has a high strength-to-weight ratio, so it’s used in common applications like wheels (for cars and motorcycles). “Many. . .automotive companies (Audi, Ford, Jaguar, Fiat and Kia Motors Corporation among them) have. . .replaced steel and aluminum with magnesium in various parts of their products. Magnesium is currently being used in gearbox, steering column and driver’s air bag housings as well as in steering wheels, seat frames and fuel tank covers,” according to the International Magnesium Association (IMA).
“Steel components in vehicles can be replaced by a single cast piece of magnesium adding to the strength of the material and allowing for housings to be cast into place. This castability also requires less tooling and gauges which lowers manufacturing cost.” (IMA)

Forged magnesium wheels (like the ones produced by SMW Wheels) are one-third lighter than comparable aluminum ones. The weight of a vehicle’s wheels affects dynamics (magnesium wheels help achieve faster acceleration and help reduce stopping distance) among other performance parameters. Magnesium wheels have excellent damping capacity (that means they’re really good at absorbing shocks and vibrations), and also dissipate heat better, thus preventing brakes from overheating. And forged magnesium wheels, often chosen as an aftermarket wheels upgrade for supercars and racing cars, give a vehicle a distinctive, stylish, more expensive look. (SMW’s proprietary net-shape hot forging process produces top-of-the-line forged alloy wheels and blanks for cars and motorcycles). Magnesium is abundant in nature and highly recyclable, therefore a very sustainable material. With the greatest source of post-consumer scrap magnesium being end-of-life vehicles (ELVs), effective processes for recycling scrap magnesium could lead to a measurable decrease in greenhouse gas emissions.

Carbon fiber is being used in everything from auto seats and interior trim to major body parts and components (hoods, roofs, trunk lids, door panels, bumpers, spoilers).
Carbon fibers are composed mostly of carbon atoms and are about 5–10 micrometers in diameter; the atoms are bonded together in crystals, and several thousand carbon fibers are bundled together to form the desired end-use material. Carbon fiber is stiff, has high tensile strength, low weight, and high temperature tolerance. Global automakers from BMW to Lexus to Ford are increasingly applying carbon fiber to racing models, street-legals and special editions to achieve significant weight reduction and to offset corrosion issues.

Aluminum, although not as light as magnesium, is a go-to metal because it is light (automakers can increase dent resistance by making body panels thicker while still lowering weight), it makes a car strong (“Pound for pound, aluminum can absorb twice the crash energy of mild steel. Larger crush zones can be designed without corresponding weight penalties,” says The Aluminum Association), and recyclable (“At the end of a vehicle’s life nearly 90 percent of the aluminum, on average, is recycled.” The Aluminum Association

High-Strength Steel The lighter-weight, strong, affordable material is finding its way into more new car models every year, to provide a cost-effective, design-flexible solution to the demand for increased safety and fuel economy. High-strength steels have a “carbon content between 0.05–0.25% to retain formability and weldability. Other alloying elements include up to 2.0% manganese and small quantities of copper, nickel, niobium, nitrogen, vanadium, chromium, molybdenum, titanium, calcium, rare earth elements, or zirconium.” (Wikipedia) Advanced high-strength steel used in body and chassis applications can help make a car safer (because of its energy absorbing characteristics) and more environmentally viable. These alloys are used in structures designed to handle large amounts of stress; they have a good strength-to-weight ratio and are resistant to rust.

Significant weight reduction and greater fuel efficiency; better performance and mechanical reliability; lower maintenance costs; more corrosion resistance. These and many more superior characteristics of a variety of advanced, specialty and high performance materials, used alone or in combination in alloys of different proportions, are changing the shape, the style, the speed, the safety of what and how we drive.