Additive manufacturing (AM), also known as 3D printing, is growing fast at around 20% annually. However, until recently, engineers have had limited options when 3D printing with stainless steel as only a few grades were available as powder. This left a gap in the market, which Outokumpu is now closing with our wider range of stainless steel powders.
Using AM enables engineers to produce components individually or in small batches quickly and without special tooling. When working with metal, 3D printers deposit thin layers of metal powder and fuse them together with a laser to build up the workpiece. It’s a technique that can use any metal alloy – but stainless steel and nickel alloys are particularly attractive as they have good corrosion resistance and mechanical properties.
"With powder as a raw material, it’s possible to print highly complex, customized products that would be difficult or costly to make using traditional manufacturing techniques,” says Andoni Sanchez-Valverde Erice, Sales/R&D engineer at Outokumpu Metal Powder.
“However, additive manufacturers need choice when it comes to alloys as different grades are needed in different applications. Varying the type and quantity of alloying elements such as chromium and nickel creates different grades of stainless steel. This provides flexibility for environments may contain corrosive salt, acid, alkali, chlorides or complex biochemical contents.
“By matching the grade to the conditions, engineers can create components that will be long-lasting and resilient for industries such as aerospace, healthcare, oil & gas and automotive.
“We believe this will create new opportunities to produce high-performance parts. As a result, we expect stainless steel to be the AM industry’s most-used feedstock by 2027.”
Powder production plant at Krefeld
“We started producing stainless steel powder at our atomization plant in Krefeld, Germany in March 2023. Because it's next to our rolling mill, we have access to offcuts from the rolling mill to produce high-quality stainless steel powder for 3D printers. This supports our sustainability goals by recycling what would otherwise be scrap and minimizing transport emissions.”
“We can use every type of stainless steel being processed in the mill, or source high quality scrap from elsewhere to produce powder in a wide range of stainless steels and nickel alloys. This gives additive manufacturers a wider choice of alloys for 3D printing of components for demanding applications.”
The quality of the powder is as important as the grades that are available. For best results, 3D printers need powder made up of regular spherical particles. This ensures the powder flows well and forms consistent layers with minimal flaws that could be the starting point for corrosion or fatigue.
By controlling quality, we produce powders that achieve up to 99.9% density. In turn, 3D printed parts have consistent properties such as tensile strength, and improved surface quality. This means less need for post-processing such as heat treatment, hot isostatic pressing or polishing.
“Because we focus on quality in a wide range of alloys, our powders can be turned into high-performance components such as heat exchangers in oil and gas, or exhaust systems in the aerospace or automotive worlds. Alternatively, they could form surgical hip or knee implants for individual patients in medicine.”
“We’re hoping the powder plant will do more than simply making metal powder. We see it as part of a wider stainless steel AM ecosystem that helps customers specify, design, and manufacture printed components.”
“It’s a facility with potential for two sets of customers. The first is companies that already work with stainless steel but have yet to explore additive manufacturing. The second group includes customers with experience in additive manufacturing but want to use higher-alloyed stainless steel grades and work more sustainably.”
AM for sustainability
Outokumpu is currently involved in two projects related to AM's sustainability. One is the development of the first commercially available martensitic stainless steel powder. It will provide high strength and hardness to enable the production of lightweight components that provide a long life in special applications. The benefit of lightweighting is that the lower the weight of parts, the less energy they require to operate during their life, while fewer raw materials and less energy is needed for their manufacture.
We’re also working on a life cycle assessment (LCA) of 3D printing with our alloys. This will cover every step from powder production to printing and post-processing. It will enable engineers to compare the CO2 emissions of 3D printing against traditional manufacture.
In another project in Finland, we’re working to create a nickel-free powder for applications where allergic reactions are a concern. This will include a life cycle assessment to determine the environmental benefits of using this new material compared to traditional alloys.
Streamlining inventories
Another opportunity for the technique of AM is its potential to save costs and lead times for spare parts.
Today, industrial companies maintain large stocks of spare parts and components to replace critical equipment that experiences sudden failure. However, this ties up cashflow and resources in spare parts that may never be needed.
By using 3D printing to produce metal components on demand, companies could reduce the need for warehousing and free up cash while keeping control over the risk of downtime. In addition, 3D printing makes it possible to custom-produce spares for older machines, keeping them in service for longer.
“This approach is already well-established in producing and honing prototypes for product development, where 3D printing helps to reduce time to market. It could even have a role in space, by enabling astronauts to produce replacement parts in orbit, reducing the weight and cost of sending components into space.”
Scaling up production
Until our atomizer started up in March 2023, most stainless steel powders on the market were based on widely-used grades such as 17-4PH or 316L. It was possible to source powder in the form of high-performance nickel alloys that provide excellent corrosion resistance – however, these have the drawback of very high prices.
That left a big gap in the middle for alloys with good properties at a more affordable price. By making those alloys available as powder, we’re creating new opportunities for engineering and industrial designers to explore the potential for 3D printing in a wide range of applications.
With a production capacity of up to 300 tonnes per year, we’re geared up for the new era of 3D production.