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NanoSteel Expands Material Capabilities for Additive Manufacturing
NanoSteel leveraged its 2014 breakthrough in additive manufacturing wear materials to print a bearing using the powder bed fusion process.
Photo courtesy of NanoSteel.
Powder portfolio enables the printing of complex high-hardness parts and crack-free gradient designs
Building on its 2014 breakthrough in additive manufacturing (AM) wear materials, NanoSteel® has expanded its additive manufacturing (AM) material capabilities to support metal 3D printing of complex, high hardness parts and the ability to customize properties layer-by-layer through gradient material design. NanoSteel, which uses proprietary technology to design and develop nano-structured steel materials, had announced last September that it successfully 3D printed a high-hardness metallic part—a fully dense (99.9%), crack-free sample with wear resistance reportedly comparable to conventionally manufactured M2 tool steels. The Providence, R.I., company recently leveraged this milestone in AM wear materials to print a bearing and impeller using the powder bed fusion process.
According to a release from NanoSteel, the parts were measured to be fully dense and crack-free, with hardness levels greater than 1000 HV. The ability to deliver these properties in functional parts, company representatives say, is a significant step forward in the development of metal powders that enable affordable, robust industrial components produced on-demand through the 3D-printing process.
As a result, NanoSteel is now building an AM powder portfolio that offers affordable 3D printing of high-hardness and high-wear resistant alloys, explained Harald Lemke, NanoSteel’s vice president and general manager of engineered powders, in an e-mailed response. “The challenge with current hard ferrous alloys is that they tend to crack in the additive manufacturing process, and other hard materials, such as WC-Co and/or ceramics, are difficult or very expensive to print,” Lemke said.
The company’s AM powders enable the design of alloys tailor-made for performance requirements, providing OEMs with multiple options to achieve key performance criteria through additive manufacturing. Although alloy content can be specified to the performance of a part, the idea is to design the alloys to function with the process conditions of additive manufacturing in mind, Lemke explained. The largest markets for affordable ferrous alloys are the industrial markets, such as oil and gas and machine tools, Lemke said, adding that there are also sizeable shorter-term markets—such as tool and die and bearings—that can benefit from high hardness, abrasion-resistant parts.
NanoSteel has taken a significant step in the development of metal powders that enable affordable, robust industrial components produced on-demand through the 3D printing process, as shown with this impeller.
Photo courtesy of NanoSteel.
NanoSteel (www.NanoSteelco.com) used a combination of high hardness and ductile alloys to create a part with a gradient design. The company worked with Connecticut Center for Advanced Technology to generate part samples using freeform direct laser deposition, achieving a seamless transition between the hard and ductile properties without subsequent heat treatment.
Gradient material designs are said to offer the equivalent of Digital Case Hardening™ by combining impact resistance, high hardness, wear resistance, and overall robustness in a single part. Traditional case hardening is the process of using a heat treatment on a part to harden the surface while leaving the internal material in a softer state. In Digital Case Hardening™ through additive manufacturing, no heat treatment is required.
A gradient material design is produced when two alloys are combined to create a controlled continuous variation of properties in the part—for example, from ductile to very hard. The advantages are that there is no limitation as to the thickness of the very hard surface, there is no subsequent heat treatment necessary, and there is more flexibility in deploying many different alloys and process parameters, Lemke explained. By providing this capability, NanoSteel offers OEMs considerable design flexibility in meeting part-performance requirements while taking advantage of the operational efficiencies of AM, including on-demand availability, less inventory, and lower transportation costs.
“Proprietary metal alloys that support the cost-effective 3D printing of high-quality parts will help accelerate the transition from subtractive to additive manufacturing across applications such as wear parts, bearings, and cutting tools,” said Lemke in a press release. “The company’s AM powder offerings make it possible to design exclusively for the function of a high hardness part, releasing designers from the limitations of conventional production processes and opening new opportunities to improve performance.” NanoSteel’s targeted markets for its AM powder portfolio are tool and die, energy, automotive, and agriculture.
NanoSteel specializes in proprietary nano-structured steel material designs. During its thirteen-year history, the company has created progressive generations of iron-based alloys from surface coatings to foils to powder metals and sheet steel. For the oil and gas, mining, and power industries, NanoSteel has successfully introduced commercial applications of metallic coatings to prolong service lifetime in the most extreme industrial environments. For general industries, the company is developing an engineered powders portfolio for additive manufacturing.
Rebecca Carnes contributed reporting to this article.
Questions and Answers Regarding NanoSteel’s New Additive Manufacturing Powder
Q: What does “Engineered Powders” mean?
A: NanoSteel’s alloys are designed to meet industry requirements—they are ‘engineered’ to solve specific issues, such as wear resistance. In this department, we use powder metal approaches, such as additive manufacturing.
Q: What processes can you use with your powders?
A: Currently, we are pursuing opportunities in shot peening, additive manufacturing, hot pressing and HIP. In the future, we may expand into new areas such as MIM.
Q: What is unique about NanoSteel’s powders?
A: NanoSteel’s powders are unique due to their chemistries, which create a metal matrix composite structure at the nanoscale.
Q: What is a metal matrix composite?
A: A metal matrix composite is a material that comprises two different phases, typically featuring a hard phase that is embedded in a more ductile phase. The hard phase serves to increase the wear resistance of the material, and the ductile matrix provides toughness, allowing the material to absorb impacts that the hard phase would not be able to absorb without cracking. The phases of the metal matrix composite work in concert to provide properties that one phase would not be able to provide on its own.
Q: What is different about NanoSteel’s metal matrix composites from others?
A: NanoSteel has introduced metal matrix composite materials, which, through their small phase size, have enhanced properties. The nanostructure contains uniform hard phases distributed throughout the material, producing isotropic properties and eliminating preferential wear. Additionally, due to the small size, there is less “pull out” of the hard phases from the ductile phase, a common issue with standard composites like tungsten carbide cobalt that can lead to early failure. Although the ductile matrix phase is softer than the hard phases, in NanoSteel’s AM materials, this ductile phase is significantly harder than would be found in conventional materials, enhancing the overall wear resistance of the material.
Q: What types of applications do NanoSteel’s materials excel in?
A: Currently, we are focused on wear applications for our additive manufacturing materials. In the future, we will be developing other materials with different features that take advantage of NanoSteel’s proprietary technologies.
Q: What types of wear applications is NanoSteel working on with additive manufacturing?
A: Our wear materials excel in the areas of high abrasive wear and hot hardness. Other areas are still being explored. We have received interest from a number of different potential users of these materials—in particular, users and manufacturers of cutting tools and injection molding dies, oil and gas companies, and agricultural equipment suppliers.
Q: What makes additive manufacturing a compelling process for industry to use?
A: Reduction in inventory – you make the parts you need when you need them; high complexity parts possible without additional processes or costs; on-site manufacturing; customization—small run sizes become economical.
Q: What are the characteristics of your wear material?
A: We can make a 99.9% dense part which is higher than most casted material, and we can do this directly through AM, without HIP post-processing. Hardness levels are over 1000 Vickers, higher than tool steels, and without heat treatments. Wear resistance is equivalent to an M2 tool steel.
Q: How did you achieve full density?
A: In essence, NanoSteel is able to achieve high density due to a combination of the alloy, process parameters, and controlled cool down protocol. High density requires (1) the molten alloy to fill in voids before solidification, and (2) to avoid creating new shrinkage-related voids upon solidification. NanoSteel has designed an alloy-process parameter combination that enables high density and high hardness, while also preventing cracking in the hard metal.
Q: How do you know that the samples are fully dense?
A: The density of the sample is determined by microscopic analysis in various areas of the sample
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