Five questions to the additive expert: Super duplex in 3D printing explained

While the interest of using iron-based and highly corrosion resistant materials in additive manufacturing has grown significantly the past few years, super-duplex stainless steel has proved a challenge in 3D printing. With its reliable characteristics and inherited suitability for corrosive environments, Sandvik’s super duplex Osprey^® 2507 is durable, corrosion resistant – and sworn by from across the offshore industries.

Sandvik has been driving the materials evolution for duplex steel for decades, continuously launching alloy variations with improved performance and properties, carefully tailored to fit the needs of each customer. The recent announcement of Sandvik and part-subsidiary BEAMIT’s ability to additively manufacture super duplex has been a long time coming – as many have tried and failed to obtain the combinations’ substantial benefits in terms of application performance and business optimization.

Nikhil Dixit is Application Engineer at Sandvik Additive Manufacturing, and focuses specifically on Powder Bed Fusion (PBF) processes in AM, for suitable demands. In terms of super duplex, Nikhil has been heavily involved with the development of process parameters and material qualification for our laser PBF– so we asked him to share some of his insights.

Can you tell us about the process leading up to the point of Sandvik presenting the ability to successfully print super-duplex stainless steel to the market?

First of all, the suitability of super duplex in corrosive environments is already well known. Being a duplex materials authority, it made sense for us to leverage our profound experience and expertise to elevate the use of super-duplex stainless steel to the next level. I also want to stress that using super duplex in additive manufacturing is one thing – and printing it with great outcome is something entirely different. Thanks to Sandvik having been at the forefront of the duplex materials evolution for so long, we could leverage this unique position, and combine it with the additive know-how found within Sandvik and the BEAMIT Group, allowing for our joint capabilities to push this innovation through.

What kind of results have you seen in the printed super-duplex components, and how do they differ from those of conventionally manufactured parts?

Well, there’s more to additive manufacturing than printing alone. We take pride in using and manifesting our “Plan it, Print it, Perfect it” approach, stating that printing is just one of the seven step you need to master in order to succeed in the industrialization of additive manufacturing. This philosophy, if you will, has been ever present in this process. Using premium raw materials is essential in order to obtain a high-quality, printed component. And the super-duplex metal powder produced and optimized for 3D printing within Sandvik, definitely stands out in terms of powder characteristics and low oxygen levels. So this fact is at the very core of observing the performance of our printed Osprey^® 2507 components. We are proud of these results, indeed. In terms of tensile impact and corrosion properties, additively manufactured super-duplex stainless steel doesn’t just meet the performance of conventionally manufactured components, but actually exceeds them. We have observed components that are near fully dense (>99.9%) and crack free – even before post processing.

We’ve already established super-duplex as a durable and corrosion resistant material. What does it take to optimize it for additive manufacturing, without compromising its highly valued properties?

Again, it all comes down to the quality of your raw material – i.e., the super duplex metal powder. Since we atomize these powders in-house at Sandvik, we have a unique ability to control the full value chain, from raw material sourcing, to finished component. Every result is based on controlling the details, and from the get-go in our state-of-the-art powder plant, through the extensive additive machine park and post processing, we leave no stone unturned in order to safeguard the quality, continuity, and traceability along the additive value chain.

How would you describe the potential related to additively manufactured super-duplex, other than those of the material itself?

The industries where super-duplex stainless steel is the material of choice are also definitely positioned to enjoy the benefits of implementing additive manufacturing. AM is seen as a disruptive technology across a variety of business segments, enabling revolutionary levels of performance optimization, reduced material waste and environmental impact, as well as on-demand production – just to name a few. In the offshore industries specifically, I would say the implementation of 3D printed super duplex, including on-demand production of spare parts, decreased stock keeping, and timely deliveries, could have a revolutionary impact on profitability and performance alike.

So, from the launch of this game-changing ability… Where do we go from here?

We are very excited to partner up and get down to business with customers across the various offshore segments, to experience this in full effect. Apart from that, together with BEAMIT, we are already hard at work with developing print parameters for multiple-laser machines, in order to expand our offering to include even larger applications – which will allow for even more customers to implement AM into their operations. Acting on this rapidly expanding market, and in such an innovative environment, I definitely feel confident to say this is only the beginning.

YOU’LL LEARN ABOUT:

• Super duplex in additive manufacturing – and the enhanced corrosion properties and impact strength of 3D printed components compared to conventionally manufactured equivalents.
• Printing and heat treatment considerations to obtain the optimal ferrite/austenite structure, and the value of a fully integrated production chain.
• The Osprey^® 2507 super duplex metal powder, atomized in-house at Sandvik and tailored for additive manufacturing, including powder characteristics and distribution sizes.
• The benefits and potential impact of implementing additive manufacturing in the offshore and marine segments, along with insights from offshore end-users and industry leading AM service providers.