NanoSteel-Engineered Iron-based Alloy Powders for Additive Manufacturing (AM) Applications Requiring High Hardness and Wear Resistance

 

The NanoSteel Company, with corporate headquarters in Providence, Rhode Island, fabricates proprietary nano-structured steel material designs including sheet metal, powder metals, surface coatings and foils.

In 2014, NanoSteel announced it was expanding its engineered powder business to include additive manufacturing (AM). As a demonstration, the company produced a fully dense crack-free part using a proprietary high-hardness metal alloy. The part exhibited a reported uniform microstructure, hardness values over 1000 HV and wear resistance comparable to conventionally manufactured M2 tool steels without the need for post processing or heat treat.

Recently, NanoSteel announced it possessed the technology to customize powder material properties for metal additive manufacturing, layer-by-layer through gradient material design.

We caught up with Harald Lemke, NanoSteel Vice President and General Manager, Engineered Powders, to learn about NanoSteel and the company’s line of engineered powder materials for additive manufacturing in an exclusive AMazing® conversation.

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AMazing®Harald, thank you for your participation. In 2014, NanoSteel announced the expansion of the company’s engineered powder business into additive manufacturing. From a materials research standpoint, what discoveries did the company make that aided the development of NanoSteel’s new class of steels; nano-structured steel materials?

Harald: The Company’s genesis was the recognition that if you could design materials with unique microstructures, you could provide mechanical and physical properties that far exceeded traditional ferrous offerings. Over the past 13 years, the company has developed progressive generations of iron-based alloys and we are now applying some of these designs in powder form specifically to additive manufacturing.

Photo reprinted with permission, The NanoSteel Company, Inc. ©2015. All rights reserved.

NanoSteel microstructure.  (Photo reprinted with permission, The NanoSteel Company, Inc. ©2015. All rights reserved.)

AMazing®: At this time is industry more comfortable working with additively manufactured steel parts as opposed to additively manufactured carbide, ceramics or even other tool steels?

Harald: We believe that ferrous based powders are easier and more reliable to produce than other hard metals and ceramic materials. One major 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.

AMazing®What makes NanoSteel powders unique and suitable for additive manufacturing, such as laser sintering, to produce a high-hardness, crack-free ferrous metal part without post processing or heat treat? Is it the combination and/or use of specific nano-particles?

Harald: We always knew that NanoSteel alloys reacted well to rapid cooling rates so leveraging our portfolio into additive manufacturing product processes represented a natural extension of the company’s capabilities. There are actually no “nano-particles” used – our technology uses conventionally sized powders. The ‘nano’ refers to the size of the grain structure of the steel for some for our alloys, which are orders of magnitude smaller than most steels. The NanoSteel alloys exhibit high hardness and wear properties directly out of the additive manufacturing process – therefore no post-process heat treatments are needed to achieve the properties. This is desirable because it simplifies production and can reduce costs.

AMazing®: In terms of hardness and abrasion resistance, the NanoSteel part proved harder and close in abrasion resistance to M-2 Tool Steel. When NanoSteel materials are subjected to laser sintering, how does the grain size change?  How does the change in grain size affect hardness and abrasion resistance?

Harald: Because the alloys were designed with rapid cooling in mind, we always have very fine microstructure. This refinement of the grain structure improves properties such as hardness and wear resistance.

Photo reprinted with permission, The NanoSteel Company, Inc. ©2015. All rights reserved.

Hardness Chart-(Photo reprinted with permission, The NanoSteel Company, Inc. ©2015. All rights reserved.)

Photo reprinted with permission, The NanoSteel Company, Inc. ©2015. All rights reserved.

Abrasion Resistance Chart-(Photo reprinted with permission, The NanoSteel Company, Inc. ©2015. All rights reserved.)

AMazing®Recently, the company announced it possessed the technology to customize powder material properties for metal additive manufacturing, layer-by-layer through gradient material design.  Would you please explain the benefits of gradient material design as it relates to the manufacture of complex, near net shape wear parts?

Additively manufactured impeller from NanoSteel medal powders.  (Photo reprinted with permission, The NanoSteel Company, Inc. ©2015. All rights reserved.)

Additively manufactured impeller from NanoSteel medal powders. (Photo reprinted with permission, The NanoSteel Company, Inc. ©2015. All rights reserved.)

Harald: In many cases, it is desirable to build parts that have different material properties from one location to another. A part could be designed, for instance, to have a very hard end surface for wear resistance, with the remainder of the part being ductile to provide for impact resistance. This is traditionally achieved through the case hardening process, where heat treatment of a part hardens the surface while leaving the internal material in a softer state.

In a gradient material design, this part can achieve a controlled continuous variation of properties by combining two alloys – as an example, from ductile to very hard. By using NanoSteel’s Digital Case Hardening™ through additive manufacturing, no subsequent heat treatment is required. The advantages are that there is no limitation as to the thickness of the very hard surface, there are fewer processing steps, and there is more flexibility in deploying many different alloys and process parameters.

AMazing®: Is NanoSteel working on other nano-structured steel materials that would be less sensitive to fatigue associated with surface stress risers, less susceptible to intergranular fracture stemming from hydrogen embrittlement and less prone to heat affected zone issues associated with welding?

Harald: NanoSteel has what we call a ‘platform technology’ meaning that the core innovations can be applied to solve many different types of problems. We are working on materials that are less prone to fatigue failures associated with surface stress risers as well as materials that are less prone to heat affected zone issues. Fractures stemming from hydrogen embrittlement are more difficult to mitigate given the complexities of the failure mechanisms and are therefore more of a longer term project.

Photo reprinted with permission, The NanoSteel Company, Inc. ©2015. All rights reserved.

Additively manufactured bearing from NanoSteel metal powder.  (Photo reprinted with permission, The NanoSteel Company, Inc. ©2015. All rights reserved.)

AMazing®What types of parts are best suited for NanoSteel metal powders? What industries, applications and situations would be best served?

Harald: Our focus is on industrial markets that can most benefit from robust high hardness abrasion resistant parts, which includes the oil & gas and tooling industries.We believe bearings and impellers and typical tool steel applications are potential early applications for additive manufacturing using the NanoSteel AM powder portfolio, as they can benefit from the ability to generate more complex designs in a highly wear resistant material.

AMazing®Is NanoSteel involved in the development of any nano-structured multi-materials?

Harald: Our gradient materials are an example of a multi-material system. Investigations are ongoing to decide whether our gradient materials will have nano-structures through the gradient. Developments are also ongoing to test the compatibility of our materials with non-NanoSteel alloys.

AMazing®: As the additive manufacturing industry rapidly evolves over the next several years, what’s next on the horizon for NanoSteel?  What do you hope to see?

Harald: Our ambition in the short term is for NanoSteel to become the highest performing and most affordable AM-produced solution for markets that require high hardness wear resistant parts. Longer term, we expect to further expand our portfolio to include alloys with property sets beyond wear resistance, introduce alloys for use in different AM processes, and there is even potential to explore mixed materials solutions.

This concludes our interview. Thank you very much Harald for your participation. We are very grateful for the opportunity to learn about NanoSteel and NanoSteel’s engineered powder materials for metal additive manufacturing.

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AM_Harald_Lemke_HeadshotAbout Harald Lemke:
Mr. Lemke, Vice President and General Manager, Engineered Powders, NanoSteel, has more than 20 years of experience in managing and growing advanced metal, ceramics, plastics, composites and specialty chemicals materials businesses in oil & gas, energy, automotive and various other industries. Prior to joining NanoSteel, Mr. Lemke was global vice president materials marketing at Sulzer-Metco, a $650M high-performance coatings division of Sulzer Ltd., where he was responsible for directing marketing and management of six product lines and assisting with acquisitions by identifying and conducting due diligence on potential targets.

Previous to this, Lemke was with Kennametal, where he rose from chief operating officer & general manager of the company’s Powdermet subsidiary to new business development manager at the Kennametal’s headquarters office. Prior to this, Lemke was director of business development and strategic planning at ConocoPhillips, financial and strategic analyst at Air Liquide and senior research chemist at Nalco/Exxon Energy Chemicals, L.P. Lemke received his Master degree in chemistry from the Technical University in Clausthal in Germany, Master of Business Administration from Rice University and Ph.D. in technical chemistry from RWTH Aachen University in Germany.

About NanoSteel
NanoSteel, a leader in nano-structured steel materials design is commercializing powdered metals for additive manufacturing to support cost-effective, high-quality components. The company’s ferrous powders feature high hardness and wear resistance enabling the 3D printing of products such as wear parts, bearings, and cutting tools. NanoSteel’s AM powder portfolio offers OEMs design flexibility to support increased geometric freedom and improved performance.

All photos reprinted with permission, The NanoSteel Company, Inc. ©2015. All rights reserved.
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Republication or redistribution of AMazing content, including by framing or similar means, is expressly prohibited without the prior written consent of AMazing. AMazing® is a registered trademark of Amazing AM, LLC.

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