Super duplex in additive manufacturing – a gamechanger offshore

How do you determine the time and temperature when heat treating the additively manufactured super-duplex parts with various thickness, sizes, and dimensions, in order to achieve the 50:50 duplex phases?
To start with, chemical composition of the powder is very important for the final phase balance of 50:50 ferrite and austenite. It is common to simulate time temperature diagrams for the material to study the structure. Thickness and size dependency is usually calculated using the simulations and thermocouples, to check if the core has the same temperature as desired during the heat treatment. Regarding thickness dependence, experiments are carried out to determine holding time for increase in the thickness. Cooling rates are important in duplex and hence suitable measures are taken while performing the heat treatment.

How do you heat treat Osprey^® 2507?
Osprey^® 2507 is a solution annealed after AM process in order to restore the phase balance. You can find more information about temperature ranges in the material datasheet.

How do you maintain the appropriate 50:50 austenite/ferrite microstructure in printed components, compared to wrought materials?
It’s all about the right post processing and heat treatment. After printing you elevate the temperature to around 1100°C, then you cool down the material at a certain rate to get the right phase balance and to avoid the detrimental phases. At a certain temperature, the phases won’t change but will remain stable in the microstructure.

What heat treatments have been done on the 3D-printed super-duplex impeller? Was there any deformation after heat treatment? What were the post AM processes, if any, to achieve the necessary surface quality?
Regarding the heat treatments, kindly refer to our material datasheet. There was no deformation of the impeller during/after the heat treatment. In order to improve surface quality, several post processes can be utilized e,g, blasting, trumling, D-Lyte, etc. Effects of these processes, especially on the corrosion performance, are soon to be published.

Which heat treatment process was used when creating the 3D-printed impeller?
Osprey^® 2507 is solution annealed after AM process in order to restore the phase balance. You can find more information about temperature ranges in the material datasheet. When heat treating Osprey^® 2507, the chemical composition of the powder is very important for the final phase balance of 50:50 ferrite and austenite. It is common to simulate time temperature diagrams for the material to study the structure. Thickness and size dependency is usually calculated using the simulations and thermocouples, to check if the core has the same temperature as desired during the heat treatment. Regarding thickness dependence, experiments are carried out to determine holding time for increase in the thickness. Cooling rates are important in duplex and hence suitable measures are taken while performing the heat treatment.

What’s the material’s response and resulting properties with various thermo-mechanical treatments?
Kindly refer to our material datasheet.

How do you test for corrosion properties?
Corrosion properties are tested according to standard ASTM protocols. We have tested material using G48 method A and G150 with different solutions. Kindly refer to our material datasheet for more details.

When comparing additively manufactured super duplex to bar material, what’s the difference in mechanical properties and corrosion properties? And how about the influence of porosity on corrosion behavior?
It is recommended to consider Norsok standard M-630 to have all the requirement of super-duplex steels (25Cr) mechanical and corrosion properties, and material datasheet on Sandvik website for AM Osprey^® 2507 mechanical and corrosion properties. In short, AM Osprey^® 2507 fulfills and outperforms all the mechanical and corrosion requirements as per the standard. Influence of porosity on AM of Osprey^® 2507 is being studied in another Swedish collaborative project, which Sandvik is part of, and soon we will have public guidelines regarding this.

Are nickel-based alloys best for corrosion resistance?
It totally depends on which corrosion media your material works in. For example, in a sour (H2S) environment, Ni-based alloys has proven very suitable for corrosion resistance, but if you have a Cl- rich environment, the super duplex material may perform better. The corrosion resistance of a material also has to do with the concentration and temperature of the corrosive media.

Can you share some results of corrosion tests, and the ferrite content achieved?
Kindly refer to our material datasheet. Ferrite phase achieved is between 45-55%. (Check standard data)

Is there a corrosion phenomenon associated with 3D-printed Osprey^® 2507?
Yes. It is recommended to consider Norsok standard M-630 to have all the requirement of super-duplex steels (25Cr) mechanical and corrosion properties, and material datasheet on Sandvik website for AM Osprey^® 2507 mechanical and corrosion properties. In short, AM Osprey^® 2507 fulfills and outperforms all the mechanical and corrosion requirements as per the standard. Influence of porosity on AM of Osprey^® 2507 is being studied in another Swedish collaborative project, which Sandvik is part of, and soon we will have public guidelines regarding this.

How do you manage corrosion in additively manufactured super-duplex stainless steel?
Corrosion properties are tested according to standard ASTM protocols. We have tested material using G48 method A and G150 with different solutions. Kindly refer to our material datasheet for more details.

What is the effect of corrosion on the super duplex in AM compared to conventional super duplex?
It is recommended to consider Norsok standard M-630 to have all the requirement of super-duplex steels (25Cr) mechanical and corrosion properties, and material datasheet on Sandvik website for AM Osprey^® 2507 mechanical and corrosion properties. In short, AM Osprey^® 2507 fulfills and outperforms all the mechanical and corrosion requirements as per the standard. Influence of porosity on AM of Osprey^® 2507 is being studied in another Swedish collaborative project, which Sandvik is part of, and soon we will have public guidelines regarding this. Also, you can follow NACE2021 conference articles where we have compared the conventional and AM corrosion performance of Osprey^® 2507.

What is the highest tensile stress for this material today? Is there a material that could be treated after printing to obtain a “memory effect”, like springs?
You can find the material properties at various temperatures in our material datasheet. Osprey^® 2507 does not give any memory effect. SMAs can be interesting to see in future.

What are the material properties of Osprey^® 2507 AM, compared to a rolled/forged and solution annealed material of the same chemical composition?
It is recommended to consider Norsok standard M-630 to have all the requirements of super-duplex steels (25Cr) mechanical and corrosion properties, and material datasheet on Sandvik website for AM Osprey^® 2507 mechanical and corrosion properties. In short, AM Osprey^® 2507 fulfills and outperforms all the mechanical and corrosion requirements as per the standard. Influence of porosity on AM of Osprey^® 2507 is being studied in another Swedish collaborative project, which Sandvik is part of, and soon we will have public guidelines regarding this.

What are the material properties of super-duplex stainless steel?
Kindly refer to our material datasheet.

Is there any directional texture in properties (strength or toughness) depending on the build orientation?
No, we have seen statistically coherent mechanical properties with no directional effect with respect to build orientation.

How do the mechanical properties of AM components compare to conventional forging or HIP processes?
It is recommended to consider Norsok standard M-630 to have all the requirements of super-duplex steels (25Cr) mechanical and corrosion properties, and material datasheet on Sandvik website for AM Osprey^® 2507 mechanical and corrosion properties. In short, AM Osprey^® 2507 fulfills and outperforms all the mechanical and corrosion requirements as per the standard. Influence of porosity on AM of Osprey^® 2507 is being studied in another Swedish collaborative project, which Sandvik is part of, and soon we will have public guidelines regarding this.

What is the yield and ultimate tensile strength for the material? What other characteristics can be expected, e-modulus, etc.?
Kindly refer to our material datasheet.

Is the 3D-printed super duplex showing cracking defects? And does the material require any special parameters or laser strategies?
Yes, several attempts have been made to print crack-free material. Previous research with AM has also resulted in cracking in the material. Optimizing the process parameters with the right chemical composition of the feedstock powder is key to solving this issue. We also license our process parameters, kindly contact us for more details.

Approximately how long does it take, and how much does it cost to print in super duplex?
It depends on the part geometry and volume. Kindly contact us with CAD file to get a cost estimate for the components.

What does the additive process look like when printing small parts in super-duplex stainless steel?
The additive/printing process is similar to other metal alloys when it comes to the process itself. It is the printing parameters and the post-processing/heat treatment that differs and needs to be understood, developed, and controlled.

Do you have a set of parameters to achieve close to 100% dense parts?
Yes, we have consistent values with 99,97% mean value. Kindly contact us if you are interested in the process parameters, as we license them as well.

What main challenges have you faced during the implementation of this process?
We have seen a challenge in getting a crack-free as-printed component, before heat treatment, especially in larger components.

What do you see as the main barriers for the offshore industry to incorporate AM-designed parts into critical well control applications?
One of the main barriers is to have a reliable and by the industry-accepted standard for metal AM parts so the offshore industry can trust and rely on these manufacturing methods. Another barrier would be to have a more industrialized production with more metal alloys available.

What should be considered when designing subsea components as per DNVGL-RP-F112?
I think the standard itself explains about design recommendations and it would be suitable to follow when designing the subsea components.

How does additive manufacturing relate to cutting tools?
Today, the cutting tools themselves are not printed, but rather the holders of cutting tools. A printed cutting tool doesn’t have the required mechanical strength as a traditionally manufactured cutting tool and cannot be used for this application since it will break after just a short while.

What do you think lies in the future for cutting tools in manufacturing?
Hard to say at the moment, mostly very small batches of customized tools on demand. This will require a new technique to acquire the mechanical strength needed. Today, the cutting tools themselves are not printed, but rather the holders of cutting tools. A printed cutting tool doesn’t have the required mechanical strength as a traditionally manufactured cutting tool and cannot be used for this application since it will break after just a short while.

I think manufacturing time is the biggest concern with 3D printing. How are we going to overcome this issue, do you think?
Compared to conventional manufacturing, the manufacturing time has actually been identified as one of the main reasons and benefits to switch to AM. It also depends on the reason you have to switch to AM for your component –The production cost itself will seldom go down by switching from conventional manufacturing to AM, but you would rather need other values and reasons. Some machine manufacturers have tackled this problem by adding more laser sources in their machines, others have sped up the powder distribution process.

Can you tell us a bit more about using diamond composite in additive manufacturing?
Yes, we do have a process for manufacturing diamond composite parts. It has a unique set of material properties, suitable for a variety of applications. Please contact us directly at additive.manufacturing@sandvik.com if you want to find out more or how it will suit your application.

Are you interested in applying graphene in AM?
Graphene addition is definitely an interesting material which can give interesting enhancement to additive manufactured materials.

What’s your application range and materials portfolio?
We are the most diverse service bureau with some of the largest AM systems on the market, involved in all major applications and markets. We have the widest material portfolio on the market today. There are over 1000 AM grades we can manufacture. Our special alloys include FeCrAl, diamond composite and tungsten carbide together with our complete alloy portfolio.

Can you explain the relationship between reverse engineering and 3D printing?
For many spare parts that are obsolete, too old and can’t be manufactured through conventional methods anymore, you can 3D scan the old part, make a CAD file of it and print a new part according to the obsolete/original part.

What is your most significant difficulty in getting new customers to perceive AM as an option? Or are there no associated difficulties at all?
It is for the customer to understand the complete AM perspective of manufacturing – not all materials or components should/could be made by AM. There’s also a big gap in existing QA procedures with existing manufacturing procedures for a material, compared to the same material made by AM. A third challenge is the relatively low amount of existing printable material – around 30 metal alloys exist today.

What does the accuracy of roundness look like for metal 3D printing? And is it possible to machine printed parts?
Roundness accuracy can be dependent on the orientation and position of the hole or rod. Vertical, angled, and horizontal direction has slight difference in the accuracy of roundness. This is mainly due to overhangs during print, support, solid supports and position in the build chamber. This accuracy can be achieved with process parameters and suitable measures. Also, yes, it is possible to machine parts, but again it also depends on the complexity of the parts (e.g., internal channels cannot be machined with some constraints).

How much can 3D printing in metal substitute conventional machining processes?
This is a very hard question to answer. The best speculations and forecast from market reports, estimate that around 3-5% of today’s existing conventional machining processes will be replaced by 3D printing. But we should not forget that 3D printing also brings more opportunities to machining, since you very often need to machine your part afterwards.

How does the laser powder bed fusion process work?
Kindly refer to our videos explaining about additive manufacturing where you can see powder bed fusion process.

How do you achieve the complex precision in metal 3D printing?
With right processing parameters and design for additive manufacturing knowledge, it is possible.

Could you tell me a bit more about metal process parameters and settings?
Metal process parameters in the laser powder bed fusion process is a diverse topic. There are certainly various parameters involved, regarding optics, environment, base plate, etc. If we try to optimize the process parameters for a certain material, we usually see three main regions depending on the input energy, namely lack of fusion, full dense and keyhole regions. Apart from this, cracks might be another dimension while processing the material parameters. If you are interested in Osprey^® 2507 process parameters, we license them as well. Kindly contact us for more details.

What is the percentage of cost difference between machining and additive manufacturing? Also, how much tolerance can be achieved directly?
This is nearly impossible to answer as it differs from case to case, materials, AM technique and applications.

I’m curious about printing in nitrogen atmosphere. What is the average loss of nitrogen during printing?
Definitely, it is suitable to print in Nitrogen atmosphere. We have observed not more than 500 ppm of nitrogen loss. Again, composition can be tailored for optimum nitrogen in the printed parts.

What else is on Sandvik’s metal powders roadmap?
There are over 1000 AM grades we can manufacture, so powder is no problem, but regarding the material/print parameter development for duplex, we will start with the Osprey^® 2507 and, depending on the response from the market, perhaps investigate hyper duplex 2707 material in the future. Our special alloys include FeCrAl, Diamond composite and Tungsten carbide together with our complete alloy portfolio.

Could you provide an equivalent AM material selection guide?
We don’t have anything similar AM material as for Osprey^® 2507 As for our material portfolio, there are over 1000 AM grades we can manufacture. Our special alloys include FeCrAl, Diamond composite and Tungsten carbide together with our complete alloy portfolio.

Is Sandvik developing a material with high elasticity and hardness, to be applied in i.e., coil springs?
Not currently, but if the market demand is high, we might consider it in the future.

What metal powders are possible to use in additive manufacturing?
Today there are around 30 available metal alloys with developed parameters for 3D printing. There are over 1000 AM grades we can manufacture. Our special alloys include FeCrAl, Diamond composite and Tungsten carbide together with our complete alloy portfolio.

When it comes to the powder classification, it depends on what quality you want (inert gas atomized, vacuum atomized, water atomized) and what AM technique you use. Below are some particle size distributions for some of the common metal AM techniques (taken directly from the data sheet):