A few years after fuel economy standards increased, Ford announced the 2015 model year F-150 pickup truck would be aluminum-intensive. It debuted at the 2014 North American International Auto Show and went on sale a few months later. In that same year, Ducker Worldwide completed a vehicle materials content study and concluded, “Within the decade… Seven out of 10 new pickup trucks produced in North America will be aluminum-bodied.” Although this forecast was a wake-up call for the steel industry, it was not a big surprise to the automotive industry. After all, vehicle manufacturers, suppliers and all those involved in automotive, were well informed of the changing fuel economy regulations including the final target of 54.5 mpg by 2025, based on the vehicle mix in 2011, with more than half of the market represented by cars.
Automakers began to address the challenges by using technology that was on the shelf and ready to use but hadn’t been needed yet. It was also known these technologies would only achieve a portion of the required fuel economy improvements and more innovations were necessary. Powertrain, aerodynamics and lightweighting represent the top three categories most impactful to fuel economy so many developments began happening quickly in these segments. The body and closures make up almost one-third of the mass of a vehicle so debates started about what materials yield the best mass reduction and would the cost justify use of these materials to achieve fractional improvements in miles per gallon.
It’s been five years since this forecast and several new fully-redesigned, steel-intensive pickup trucks have been introduced over that span: 2015 Chevrolet Colorado/ GMC Canyon, 2016 Toyota Tacoma, 2016 Nissan Titan, 2018 Chevrolet Silverado/ GMC Sierra, 2019 Jeep Wrangler, 2019 Jeep/Gladiator, 2019 Ram 1500 and the 2019 Ford Ranger. How could the Ducker forecast be so far off, when their information came directly from the automakers who design, engineer and build the vehicles? Let’s take a look at why steel remains the dominant material for automotive body structures and closures.
Steel has two major advantages over competing automotive structural materials: physics and collaboration.
Steel is composed of iron and a very small amount of carbon, adding small amounts of other alloying elements (such as silicon, manganese, etc.) and certain material processing yields a wide variety of grades ranging in strength from approximately 200 to2,000 MegaPascals (29-290 ksi). The steel industry provides more than 200 grades of automotive sheet steel to give the right combination of properties for each of the hundreds of parts that make up a vehicle’s body. Each part has its own design and manufacturing requirements, which vary by vehicle and automaker. With pressure to maximize lightweighting and be competitive, automakers can benefit from the flexibility offered by this wide variety of steel grades and properties.