Penn State to develop new method of 3D printing ultra-tough steel for U.S. Army

Researchers based at Penn State’s College of Engineering have been awarded $434,000 by the U.S. Army to develop an optimized method of 3D printing high-strength alloys. 

During the project, the team intends to use computer modelling to identify a Laser Directed Energy Deposition (L-DED)-based setup, that’s capable of printing more robust metals with enhanced material efficiency. Such high-grade steels could have multiple defense-related applications, ranging from bulletproof vests to blast-proof protection for the hulls of naval ships. 

“These materials are a completely new class for additive manufacturing,” said Amrita Basak, Co-principal Investigator on the project. “What we find can help the research community pursue this further, and perhaps the Army will discover new ways to use these materials to further their mission.”

A mock-up of a wheeled tank in the process of being 3D printed.
An unusual-looking tank in this artist’s impression. Penn State engineers are developing an optimized system of 3D printing large-format military components. Image provided by Penn State via iStock, DEVRIMB.

Printing parts for active service

Essentially, the U.S. Department of Defense (DoD) coordinates the activities of the Army, Navy, Space Force and other U.S. military organizations, including their spending priorities. Under this remit, the DoD has invested heavily in integrating 3D printing into each force’s operations, and recently unveiled its first ever strategy for rolling-out the technology. 

In terms of defense applications, 3D printing has shown particular potential as a means of creating spare parts on-demand, something that could be advantageous to isolated soldiers on the battlefield. As a result, the DoD has commissioned ExOne to develop a ‘portable 3D printing factory,’ that’s capable of producing spares anywhere in the world. 

Similarly, the U.S. Army has previously acquired a Rize One 3D printer for on-demand production purposes, and adopted MELD Manufacturing technology to repair military vehicles on the move. However, questions over reliability continue to prevent the further roll-out of additive parts within the military, as they often need to be demonstrably bulletproof to make them useful in end-use scenarios. 

In an attempt to address this, the U.S. Army’s Research Lab (ARL) has chosen to adopt machine learning (ML), as a means of better understanding part wear. For instance, the ARL recently deployed Senvol’s ML software to assess the efficacy of 3D printed missile parts, and using similar simulations, engineers at Penn State are now seeking to qualify their alloy-based approach, albeit for larger-format applications. 

The ARL is aiming to use Senvol's ML algorithm to develop a method for qualifying 3D printed missile parts. Photo via the ARL.
The U.S. Army is increasingly using simulation-based approaches to qualify 3D printed parts for end-use within combat scenarios. Photo via the ARL.

Penn State’s novel approach 

While it’s clear that robust 3D printed metal parts have significant potential when it comes to military shielding, some performance alloys can be difficult to process. In particular, high-grade steels are more prone to cracking, and exhibit low weldability compared to conventional materials, limiting their defense-related applications. 

To get around this, Basak now intends to work with the project’s Principal Investigator Todd Palmer, to develop an optimized wire-fed manufacturing process. As opposed to powder-fed machines, the engineers anticipate that adopting a wire-based approach could enable them to make the process more cost-efficient, while wasting less material as well. 

According to Palmer, Penn State is uniquely well-positioned to conduct the research: “Our vertical integration around AM is a real strength at Penn State,” said Palmer. “We have experts on the experimental side, and also on materials, numerical methods and machine learning. That’s what sets us apart: we can bring these people across disciplines together.”

During the project itself, the team is set to use computer modeling to test and refine the parameters of their process, before simulating end-part performance. Once perfected, the engineers then aim to assess their approach practically, using Penn State’s machines to create large-format test parts, and generate experimental data that could prove useful in future end-use military scenarios. 

For Basak, having access to Penn State’s extensive 3D printing resources, will prove vital to testing the efficacy of their approach. “In this project, we are exploring very large structures,” concluded Basak. “If we didn’t have 3D printers large enough to create these, we couldn’t do much. But we have many, and we will need them all to successfully complete this project.”

Recent innovations in L-DED 

Wire-fed DED is quickly emerging as a faster and cheaper alternative to similar powder-based technologies, and Sciaky has established itself as one of the market leaders in this area, with its high-deposition rate EBAM 3D printers

The company has often been contracted to 3D print defense-related parts under NDAs, but in 2017, it opted to publicise a project that saw it fabricate a metal AUV submarine component. Elsewhere, EBAM has also been used to create the internal structure of airplane wings, reflecting the broad potential of wire-fed technologies. 

In a similar vein, Reliance Precision and the University of Huddersfield are working on a potential alternative to EBAM as part of an Innovate UK-backed program. The joint team of engineers are essentially attempting to develop an optimized EB-based process that drives the technology’s wider industry adoption.

Likewise, Hybrid Manufacturing Technologies (HMT) is also leading an Innovate UK project, which is focused on fast-tracking the R&D of a new compact wire-feed system. Once the new DED design is ready, HMT intends to work with TWI and Epoch Wires, to optimize its performance and accelerate its market uptake.

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Featured image shows a mock-up of a tank being 3D printed. Image provided by Penn State via iStock, DEVRIMB.