Swiss Steel is creating all new possibilities through additive manufacturing and optimised metal powders.
Additive manufacturing with powder allows for high precision and detailed accuracy as the powder is applied in thin layers. It is also suitable for complex geometries and can process a wide variety of materials.
The Swiss Steel Group offers a broad range of gas-atomised metal powders based on Fe, Ni and Co. The basis for the manufacturing processes is a high-quality metal powder, which is produced by a series of complex process steps. To produce the powder, raw and base materials are first melted in an induction furnace and then fed into a gas atomisation system.
Inside a closed container, the jet of melt is then atomised under high pressure using an inert gas (nitrogen). This generates particles which assume a spherical shape during cooling. This is the only way to guarantee the desired flow behaviour which is critical for further processing. The spherical shape also improves the dosability of the powder. This part of the process is wholly performed under inert gas, which lets the powder cool without any damaging surface oxidation. The metal powder is then sieved and air-sifted. In this way, the powder is prepared, for example, for use in additive manufacturing. Too-fine and too-large particles are removed, which leaves a particle distribution of 10 – 63 µm, which is typical for 3D printing.
With the metal powder having achieved the necessary distribution of particle sizes, the base for the actual 3D printing process has been created. Finally, the powder is homogenised, then packaged and labelled according to customer requirements. As already mentioned, the powder bed process builds up components layer by layer. This is why such processes are called additive processes.
The L-PBF process uses a laser as source of energy, which welds metal powder together at micrometre level. This way, a three-dimensional component is created layer by layer, enabling the manufacture of very complex designs. This complexity, or rather its possibilities, are one of the great advantages of this new manufacturing method. But at the same time, the new possibilities also come with directly related requirements and challenges.
First, there is a demand for new and adapted raw materials in order to leverage the maximum potential of this technology.
Second, these new possibilities must also be implemented in daily industrial practice. Iron-based metal powders for 3D printing can be separated into austenitic, age-hardenable and martensitic grades.
The austenitic grade Printdur 4404 demonstrates a high resistance to corrosion and good resistance to oxidation. The grades Printdur 4545 and Printdur 4548 demonstrate an ideal combination of abrasive, corrosive and oxidative properties. For increased stress through wear, the grades Printdur Powderfort, Printdur 2343 and Printdur 2344 are a good choice.
Metal powder based on nickel is a good option for applications that need strong resistance to corrosion. Printdur Ni625 demonstrates a good resistance against mineral acids like nitric, phosphoric, sulphuric or hydrochloric acid. It is also resistant against corrosion by alkaline substances and organic acids. In its solution-annealed condition, the raw material also demonstrates good resistance towards hot-gas corrosion and a high creep rupture strength above 600°C.
Metal powder based on cobalt (Printdur CoCrF75) can be used in two different kinds of application: high temperature applications and medical technology. Printdur CoCrF75 demonstrates excellent resistance to thermal shock and is resistant to oxidising and reducing atmospheres up to approx. 1150°C. Excellent biocompatibility and resistance to corrosion are also some of its properties.
Bainidur AM (= Additive Manufacturing) expands the portfolio of metal powders. Right now, only very few low and medium alloy steels which can be processed using additive manufacturing are available on the market. However, Bainidur AM meets this demand by being able to be used for quick and effective printing of initial samples which demonstrate the same properties as the later component. Heat treatment and thermochemical surface treatments can be tested and optimised with the same raw material that will be used in mass volume production.
Even spare parts can be produced by additive manufacturing and will have properties comparable to the original. This is supported by its good conversion behaviour, which allows it to become a part of the bainite structure. It also makes the material easy to handle during printing.
Source: Swiss Steel
