A wave of aluminum auto body scrap is set to enter salvage systems over the next decade. This scrap is often too impure to safely be reused in new critical automotive parts, limiting its value. That's changing thanks to a team of researchers at the Department of Energy's (DOE) Oak Ridge National Laboratory (ORNL) who developed an innovative new aluminum alloy, called RidgeAlloy, that transforms low-value scrap into a high-value domestic supply chain for manufacturing new structural automotive parts.
DOE's critical materials list includes aluminum because it is essential to energy technologies, including those that produce, transmit, store and conserve energy.
RidgeAlloy is produced by remelting post-consumer scrap aluminum and recasting it into a material that meets the strength, ductility and crashworthiness standards for structural vehicle parts. As a world leader in aluminum alloy materials research, ORNL has developed a targeted design method to accelerate innovation.
"The team advanced from a paper concept to a successful, full-scale part demonstration of a new alloy in only 15 months," said Allen Haynes, director of ORNL's Light Metals Core Program. "That's an unheard-of pace of innovation in developing complex structural alloys."
The challenge of repurposing vehicle scrap aluminum
Aluminum-intensive vehicles entered the U.S. market around 2015, with Ford's F-150 truck series among the first to be mass produced. By the early 2030s, many of these vehicles are projected to reach end-of-life, creating a surge of high-quality aluminum body sheet scrap - up to 350,000 tons annually in North America. Much of this sheet scrap is expected to be downcycled into low-grade castings or exported, which is a missed opportunity to use those resources as a source of high-quality domestic aluminum.
"You can repurpose post-consumer aluminum into something non-structural like engine blocks," said Alex Plotkowski, ORNL group leader of Computational Coupled Physics. "But it won't have the properties needed for higher value, structurally sound body applications."
That's because the vehicle shredding process introduces impurities, such as iron, from various parts, including fasteners like rivets. This makes the scrap chemistry too unpredictable and low performing for commercial automotive structural alloys. As a result, most lightweight parts are made using primary aluminum, which is produced from raw ore in an energy-intensive process.
Turning scrap into a domestic supply chain
While primary aluminum is mostly imported, the U.S. has some of the world's best infrastructure for vehicle shredding and aluminum scrap recovery.
"Using remelted scrap instead of primary aluminum is estimated to result in up to 95% reduction in the energy needed for processing a part," said Amit Shyam, leader of ORNL's Alloy Behavior and Design Group.
To make that possible, the team applied world-class scientific tools such as high-throughput computing, which involved more than two million calculations to predict the optimal alloy compositions with targeted properties, as well as materials characterization and neutron diffraction at ORNL's Spallation Neutron Source, a DOE Office of Science user facility. These tools helped the researchers understand how specific impurities affect alloy behavior. Neutrons are uniquely suited for this kind of research because they can penetrate deep into dense metals without damaging the material, allowing scientists to observe internal structures and atomic-scale changes.
After pinpointing the desired blend through rapid computational predictions and laboratory trials, the new alloy was tested in a real-world environment. PSW Group's Trialco Aluminum in Chicago supplied recycled aluminum ingots, metal blocks ready for remelting, cast from mixed auto body sheet scrap and tailored to RidgeAlloy's specifications. The ingots were shipped to Falcon Lakeside Manufacturing in Michigan, where they were successfully cast into automotive parts using high-pressure die-casting.
"The part we chose was medium-sized and moderately complex," Plotkowski said. "The ultimate goal is to eventually cast larger parts, perhaps even automotive giga-castings, but this is the first step."
The cast parts confirmed that RidgeAlloy, consisting of aluminum, magnesium, silicon, iron and manganese, had the combination of properties necessary for structural vehicle castings, even when made from recycled blends with higher iron and silicon content. It delivers strength, corrosion resistance and ductility, enabling the production of structural castings of underbodies, frame components and other critical parts from post-consumer aluminum scrap. This breakthrough offers the opportunity to reshape the value equation of how North American auto body sheet scrap is sorted and reused.
From national laboratory to real-world impact
"This team figured out how to take full advantage of a national lab's world-class suite of capabilities to rapidly fill a huge gap in our understanding of lightweight automotive materials," Haynes said.
By the early 2030s, RidgeAlloy could enable recycled structural castings at volumes equal to at least half of the annual primary aluminum production in the U.S. This would reduce energy use, cut costs and strengthen domestic supply chains.
"RidgeAlloy offers the first technology capable of recapturing the value of a fast-approaching and historically massive wave of domestic, high-quality recycled automotive aluminum sheet alloys," Haynes said. "That's the big picture supply chain impact our team aimed for."
There is also potential for future applications in industrial machinery, agricultural equipment, aerospace, mobile power generation equipment, off-road vehicles such as snowmobiles, motorcycles, and marine vehicles including jet skis.
The project team from ORNL included Alex Plotkowski, Amit Shyam, Allen Haynes, Sunyong Kwon, Ying Yang, Sumit Bahl, Nick Richter, Severine Cambier and Alice Perrin. This research was supported by DOE's Office of Energy Efficiency and Renewable Energy, Vehicle Technologies Office Lightweight Metals Core Program.
UT-Battelle manages ORNL for DOE's Office of Science, the single largest supporter of basic research in the physical sciences in the United States. RidgeAlloy was developed under the Vehicle Technologies Office Lightweight Metals Core Program. For more information, please visit energy.gov/science. - Julya Johnson
