Andy Shives Andy Shives
Product Manager

All About Metal Alloy Powders for Additive Manufacturing

April 29, 2019


Partner Content

1. Is one metal-AM powder the same as any other powder if they have the same composition?

No, and this is something many users don’t understand. The process employed to produce the powder and the type of raw materials used can affect the performance of an AM part. For example, one atomization process may allow targeting a more strict chemistry range, which can benefit specific properties for the application. Understanding gas content also is critical, not only for achieving optimal properties but also for powder reuse, to maximize the number of builds. Regarding raw materials, users must understand the grade and type of feedstock used. They may need to use higher-purity materials to achieve the desired part properties and minimize the presence of specific trace elements. Our industry-leading experts collaborate regularly with customers on these and other considerations.

2. Can suppliers tailor the powders for use on specific projects?

Absolutely, and this is an area of focus for our team. We primarily melt using elemental (individual) raw materials, which provides optimum flexibility in tailoring powders to a custom or targeted composition. This approach proves ideal for all of the custom alloy work we perform for AM, as well as for the commonly used standard alloys. Many users have become comfortable adjusting or creating powder specifications aligned with their AM process, rather than simply using a powder spec. pulled from existing processes such as casting or forging. Tailoring the particle-size distribution (PSD) also proves important, as users continue to find ways to improve productivity and optimize build properties.

3. How does powder particle size affect performance?

As previously mentioned, tailoring powder PSD can improve productivity and optimize properties. A parameter set for a given application, for example, may require thicker layers for printing. This in turn may require larger powder particles to improve throughput, which could vary by alloy type. In addition, the required surface finish and post-processing also may affect PSD. We supply many PSD variations to customers who run the same alloy on the same AM machine due to the different parameter sets used and the specific application requirements. The AM process used can affect performance as well as the required PSD. Binder jet, laser powder bed, electron beam melting and direct energy deposition processes all have different PSD requirements.

4. How do suppliers deal with the changes in specifications as they develop metal powders for AM?

For Praxair, the flexibility of our process helps tremendously. I mentioned the elemental-raw-material approach, which allows us to adjust powder composition much more easily than melting a pre-alloyed ingot or using a wire feedstock. We also employ multiple vacuum induction gas atomizers of different scale. Our smallest unit, which supports alloy development work for the AM industry, allows us to supply powder lots of less than 50 kg, for initial build trials. We then can scale up on our larger units to meet production demand. We often manufacture many variations of the same alloy due to customer-specification differences driven by specific applications.

5. Describe some newly developed metal powders that offer a wide range of applications for builders?

The industry as a whole uses many of the same alloys, since we have developed data sets that have been proven for use in production with industry and OEM approvals. However, we continue to see more users printing with alloys considered custom or that do not have a parameter set available from the equipment manufacturer. These powders—primarily superalloys—offer key characteristics such as resistance to corrosion or oxidation not readily achieved with the more commonly used nickel and cobalt alloys. The number of titanium and aluminum alloys are even more limited, so we expect to see more alloy offerings introduced in this area soon. 3DMP

Industry-Related Terms: Post-processing, Powder bed, Surface finish
View Glossary of 3D Metal Printing Terms

 

See also: Praxair Surface Technologies

Technologies: Metal Powders

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