Over the next decade, significant amounts of aluminum from vehicle body panels are expected to enter recycling and recovery systems. Much of this material cannot currently be reused in critical auto parts because it becomes impure due to contamination. This limitation reduced its value.
Researchers at the Department of Energy’s (DOE) Oak Ridge National Laboratory (ORNL) are working to change that. A research team has developed a new aluminum alloy called RidgeAlloy that can transform low-value recycled aluminum into a reliable source of material for manufacturing automotive structural parts in the United States.
Aluminum is on the DOE’s Critical Materials List because it plays a critical role in many energy technologies, including systems used to generate, transmit, store, and store energy.
RidgeAlloy is made by remelting and recasting aluminum recovered from post-consumer products into a new alloy designed to meet the strength, ductility and crash safety requirements of vehicle structural components. ORNL researchers have developed a targeted alloy design approach that speeds the development of new materials.
“In just 15 months, the team successfully went from a concept on paper to a full-scale component demonstration of the new alloy,” said Allen Haynes, director of ORNL’s Light Metals Core Program. “This is an unprecedented pace of innovation in the development of complex structural alloys.”
The growing challenge of recycled automotive aluminum
Vehicles that rely heavily on aluminum began appearing on the U.S. market around 2015. Among them is the Ford F-150 truck series, one of the first aluminum-intensive models produced at scale. Many of these vehicles are expected to reach the end of their useful lives by the early 2030s. Recycling systems in North America could then receive up to 350,000 tons of aluminum body sheet scrap per year.
Much of this material may end up being used in low-cost foundry products or exported overseas. This means a missed opportunity to reuse this metal as a domestic source of high-quality aluminum.
“We can repurpose used aluminum into non-structural objects like engine blocks,” said Alex Plotkowski, ORNL group leader for computational coupled physics. “However, it will not have the properties needed for higher value, structurally sound body applications.”
The main challenge comes from the contamination introduced during the vehicle shredding process. Recycled metal contains small amounts of iron from components such as rivets and other fasteners. These impurities make the chemical composition unpredictable and reduce performance, preventing the material from meeting the stringent standards required for automotive structural alloys.
For this reason, most lightweight vehicle parts are still made from primary aluminum, which is manufactured from mined ore. The process requires a large amount of energy.
Domestic resource production of scrap aluminum
Although the United States imports most of its primary aluminum, the country has a well-developed network for vehicle crushing and aluminum scrap recovery.
“It is estimated that using remelted scrap in place of primary aluminum can reduce the energy required to machine a part by up to 95%,” said Amit Shyam, ORNL Alloy Behavior and Design Group Leader.
To create RidgeAlloy, researchers used advanced scientific tools to design the alloy composition. Using high-throughput computing, more than 2 million calculations were performed to predict which combinations of elements would achieve the desired mechanical properties. The team also conducted detailed materials analysis and neutron diffraction experiments at the spallation neutron source at ORNL, a DOE Office of Science user facility.
These experiments helped scientists understand how different impurities affect alloy performance. Neutrons are particularly useful for studying metals because they can pass through dense materials without causing damage, allowing researchers to observe internal structures and changes at the atomic scale.
From computer models to real car parts
After identifying the optimal alloy formulation through simulation and laboratory testing, the researchers evaluated RidgeAlloy under actual manufacturing conditions.
PSW Group’s Trialco Aluminum in Chicago produced recycled aluminum ingots made from mixed auto body sheet scrap that fit RidgeAlloy’s design. These ingots were sent to Falcon Lakeside Manufacturing in Michigan, where they were melted and cast into automotive parts using high-pressure die casting.
“The parts we chose were medium-sized and moderately complex,” Plotkowski said. “The ultimate goal is to eventually cast larger parts, such as gigacasting for cars, but this is a first step.”
Testing confirmed that RidgeAlloy contains the combination of aluminum, magnesium, silicon, iron, and manganese needed for structural automotive casting, even though recycled metals contain high levels of iron and silicon. This material provides the strength, corrosion resistance, and ductility required for demanding applications such as vehicle underbodies, frame elements, and other major structural components.
This capability has the potential to revolutionize the way automotive aluminum scrap is sorted, evaluated and reused across North America.
Extending your impact beyond the lab
“This team has figured out how to take full advantage of the national lab’s world-class suite of capabilities to quickly fill a major gap in our understanding of lightweight automotive materials,” Haynes said.
By the early 2030s, RidgeAlloy could enable recycled structural aluminum castings equal to at least half of current annual primary aluminum production in the United States. This change has the potential to reduce energy consumption, reduce manufacturing costs and strengthen domestic supply chains.
“RidgeAlloy provides the first technology that can recapture the value of historically large-scale domestic high-quality recycled automotive aluminum sheet alloys, which is rapidly approaching,” Haynes said. “This is the full picture of the supply chain impact that our team was aiming for.”
The technology could find applications beyond passenger cars. Potential applications include industrial equipment, agricultural machinery, aerospace systems, mobile power generation equipment, off-road vehicles such as snowmobiles and motorcycles, and watercraft such as jet skis.
The ORNL research team included Alex Plotkowski, Amit Shyam, Allen Haynes, Sunyong Kwon, Ying Yang, Sumit Bahl, Nick Richter, Severine Cambier, Alice Perrin, and Gerry Knapp. This project was supported by DOE’s Office of Energy Efficiency and Renewable Energy, Office of Automotive Technology’s Light Metal Core Program.
