Gearing is an area where advanced steels are flourishing. One company that develops such gear steels is QuesTek Innovations LLC. The Evanston, IL-based materials solutions company applies its proprietary Materials by Design R&D process to the design and development of not only new iron-based alloys but also those based on nickel, aluminum, titanium, and copper.
“Simply stated, QuesTek’s Materials by Design methodology uses computer technology to virtually rearrange (i.e., model and analyze) atoms of an alloy to control and predict the properties of a material without actually making alloy melts through a typically exhaustive trial-and-error process,” explained Charlie Kuehmann, President and CEO of QuesTek. “To do so, QuesTek uses proprietary Computational Materials Dynamics software and platforms, which include a suite of detailed thermodynamic and kinetic databases that fuel multilevel models to predict microstructures and associated material properties.”
While the technology’s previous capabilities dealt primarily with strength and ductility, “we now have better modeling capabilities for these materials in fatigue, corrosion resistance, and other aspects of their performance,” Kuehmann said. “With the modeling, we can now get to the point where we can integrate with the design engineer and go back and forth…to come up with a better part.”
Another aspect of the modeling technology is helping to balance costs—process cost, raw material cost, as well as life-cycle cost—with a material’s performance characteristics. For example, “can you take a less expensive material like a steel and get it to work like a titanium? Can you get titanium to work using cheaper raw materials and processing routes like castings to be able to replace, in some cases, more expensive steels?” Kuehmann posed. “So you can kind of bring the higher-cost materials down in cost and you can bring lower-cost materials up in performance to try to drive a better trade-off.”
The process typically reduces material development costs and timelines from 15 to 20 years to just a few years, he said, noting that QuesTek’s Ferrium C61 carburized steel was designed with a single prototype. C61 has a high-strength/high-toughness core to allow for weight reduction or increased power density of components compared to those made of traditional carburized 9310 steel, for example.
C61 is currently used to make V091 ring and pinions in transmissions for SCORE 1600 class off-road racing cars.
“The next development of the gear steels is an alloy called C64, which is a higher-performance variant of C61. It has the opportunity to significantly reduce the size of the transmission,” said Kuehmann. “In helicopters, we're targeting about a 25% reduction in weight of the transmissions, and I think similar benefits could be seen in off-highway or automotive.” C64 is in the specification development stage now and is expected to be market-ready in the next year or two.
Another offering, Ferrium S53, is an ultrahigh-strength, corrosion-resistant steel targeted primarily for aircraft landing gear currently. It could conceivably find application in other transportation industries, Kuehmann said, particularly areas that may have issues with stress corrosion cracking or possibly in the engine due to the material’s high thermal resistance. But he added that such alternative possibilities largely depend upon its licensees, Carpenter Technology and Latrobe Specialty Steel, and their customers’ interests.