Researchers at Tohoku University’s Institute for Materials Research and New Industry Creation Hatchery Center have achieved a major breakthrough in multi-material 3D printing by developing a process to create lightweight yet durable automobile components. This advancement demonstrates the potential of combining different materials such as aluminum and steel, through additive manufacturing to optimize the performance and efficiency of automotive parts.
Metal 3D printing, as a process, builds objects by depositing metal layers sequentially, using heat to bond them together. This approach allows for remarkable precision and enables the creation of highly customizable, intricate shapes while minimizing material waste compared to traditional manufacturing methods. Among its applications, 3D printing facilitates the production of “multi-material structures,” which strategically integrate different materials into a single component for enhanced functionality. For example, combining aluminum with steel in automotive parts can significantly reduce weight while retaining the necessary structural strength. Such benefits have made the advancement of these techniques a focal point for researchers worldwide.
Despite these advantages, challenges remain. Combining dissimilar materials, such as steel and aluminum, often results in the formation of brittle intermetallic compounds at their interfaces, which weakens the final product. As Associate Professor Kenta Yamanaka of Tohoku University explains, “Multi-materials are a hot topic in the field of additive manufacturing due to its process flexibility. However, a major challenge in practical implementation is that for certain metal combinations, such as steel and aluminum, brittle intermetallic compounds can be formed at dissimilar metal interfaces. So, while the material is now lighter, it ends up being more brittle.”
To address this issue, the research team used a process called Laser Powder Bed Fusion (L-PBF), one of the leading technologies in metal 3D printing. This method uses a laser to selectively melt metal powders layer by layer. Through their experiments, the team discovered that by increasing the laser scan speed, they could significantly suppress the formation of brittle compounds like Al5Fe2 and Al13Fe4. They determined that this higher scanning speed induces a phenomenon called non-equilibrium solidification, which reduces solute partitioning and prevents the formation of weak points in the material. The resulting steel-aluminum alloy demonstrated strong bonding interfaces, achieving both lightweight and durable properties.
Specially Appointed Assistant Professor Seungkyun Yim, who was part of the research team, emphasized the importance of a thorough understanding of the underlying mechanisms. “In other words, you can’t just slap two metals together and expect them to stick without a plan,” Yim explained. “We had to fully understand the in-situ alloying mechanism first.”
This achievement led to the successful prototyping of the world’s first full-scale automotive suspension tower created through multi-material 3D printing. This component, designed with tailored geometry, showcases the practical application of the team’s findings and marks a milestone in the use of advanced manufacturing techniques. Looking ahead, the researchers aim to apply their methods to other metal combinations that face similar challenges with bonding, potentially unlocking a wider range of applications across industries.
