A new era of lightweight automotive parts manufactured through 3D printing is upon us, driven by advancements in multi-material additive manufacturing.
Researchers at Tohoku University’s Institute for Materials Research and the New Industry Creation Hatchery Center have achieved a significant milestone in multi-material 3D printing, successfully demonstrating a method to create an automobile part that is both lightweight and robust.
The technique of metal 3D printing involves constructing objects by layering metals, with heat used to fuse the layers together. This method allows for the creation of unique, customizable designs and typically generates less waste compared to conventional manufacturing methods. 3D printing can also create “multi-material structures,” which combine different materials strategically to enhance the performance of a part. For instance, steel components can be made lighter by incorporating aluminum. As a result of these advantages, the mastery of 3D printing techniques is becoming highly sought after by researchers.
Nonetheless, this innovative approach does face some challenges.
“Multi-materials are a trending topic in additive manufacturing due to the flexibility of the process,” states Associate Professor Kenta Yamanaka from Tohoku University. “However, a significant hurdle in practical application is that certain metal combinations, like steel and aluminum, can lead to the formation of brittle intermetallic compounds at the points where the different metals meet. So, while the material is lighter, it becomes more fragile.”
The objective of this research was to create a steel-aluminum alloy that is lightweight while maintaining its strength. To achieve this, the team employed Laser Powder Bed Fusion (L-PBF), a leading metal 3D printing technology that uses a laser to melt metal powders selectively. They found that increasing the laser’s scan speed significantly reduces the formation of brittle intermetallic compounds (such as Al5Fe2 and Al13Fe4). They theorized that this higher scan speed results in a process known as non-equilibrium solidification, which lessens the solute partitioning that creates weak points within the material. The final product exhibited strong bonding interfaces as a result.
“Essentially, you can’t just combine two metals without a strategy and expect them to bond effectively,” explains Specially Appointed Assistant Professor Seungkyun Yim from Tohoku University. “We needed to thoroughly understand the in-situ alloying mechanism first.”
Thanks to this achievement, the team successfully created a prototype of the world’s first full-scale automotive multi-material component (a suspension tower) with a specifically designed geometry. The researchers aim to apply their findings to other metal combinations facing similar bonding challenges, paving the way for a wider range of applications.
The findings were published in Additive Manufacturing on November 19, 2024.
