Stellar®X15TN (1.4123 / ASTM F899) is a nitrogen alloyed, cobalt free 0,4% C martensitic stainless steel which is easy to print by LPBF despite its relatively high carbon content. The steel combines a capability to be heat treated to over 58 HRC with an excellent corrosion resistance and a good polishability. Being magnetic and relatively soft in its as built and stress relieved state it is easy to machine, which is necessary for example for drilling and threading of fixation holes. The fact that it is cobalt free is another important feature due to health concerns. Therefore, Stellar® X15TN is suitable for additive manufacturing of plastic injection molds with conformal cooling, surgical tools, cutting tools for food and pharma processing but also for other components where a combination of high hardness and corrosion resistance is requested such as bearing and valve components. Nitrogen enhances the hardness and the wear resistance of the material through formation of carbonitrides. It is also an austenite stabilizing element that reduces the martensite start (Ms) and finish (Mf) temperatures which improves the printability. Finally, nitrogen has a positive impact on corrosion resistance. The challenge is to add nitrogen and to not lose it during the additive manufacturing. Previous studies have exposed the printing parameters. This work presents different heat treatments and their impact on the main usage properties such as hardness and impact strength.

Stellar® InvHard is a Nb-enriched Invar designed for additive manufacturing (Laser Powder Bed Fusion). It will be launched on the market in 2023. Compared to Invar 36, Stellar® InvHard exhibits increased mechanical strength while maintaining a low coefficient of thermal expansion. The hardening of this alloy is inspired by superalloys 706 and 718 strengthened by Ni3Nb-γ'' phase that precipitates in the austenitic matrix; also containing carbides and Nb-rich δ phase. The precipitation of the γ'' phase can be controlled through annealing and aging treatment’s optimization, leading to a hardness in a range: 300-420 HV and the effect on coefficient of thermal expansion increase is limited thanks to the small size of such precipitates. Insights on microstructure and processability will also be presented along to coefficient of thermal expansion.

Laser Powder Bed Fusion (LPBF) is an additive manufacturing process used to produce conformal cooling injection molds with complex internal channels, mainly using cobalt-rich 18Ni300 maraging steel. Yet, built parts with this steel powder still demand improved toughness and fatigue strength. As an alternative, this work describes the manufacturibility of two alternative cobalt-free martensitic stainless steels by LPBF. After a quantitative characterisation of the microstructure, defects and mechanical properties of as-built parts, different heat treatments were performed to (i) age the precipitation-hardenable low-carbon maraging steel (CX) or (ii) temper the high-carbon martensitic steel (PM420). The hardness, tensile strength, ductility, impact energy and fatigue behavior of as-built and treated parts were compared. The influence of the microstructure and the critical defects on the mechanical behavior is discussed, with an emphasis on the fatigue life. Finally, the manufacturing of complex injection molds using PM420 powder was assessed.

TS700 is a new precipitation hardening steel with high temperature resistance and excellent hot hardness developed for additive manufacturing of aluminium die casting tooling.TS700 parts were produced by L-PBF on a plate made in H11 tool steel treated at 45HRC. The interface between TS700 and H11 is investigated, as well as the microstructure evolution versus energy density (for different laser powers and scan speeds). The evolution of the microstructure with subsequent heat treatments is presented as well as some mechanical properties associated to the different microstructures obtained.

Bio-based binder alleviate the important carbon footprint that is created during PIM-like process with a carbon cycle for the binder. Moreover, some bio-based polymer are more suited to EAM, like PLA.This work presents the different steps in developing a suitable pellets feedstock for PIM-like EAM and its optimisation to minimize porosity by tomographic observation in the final part. The work is focused in the use of a steel-tool alloy powder but using the same method other materials can broaden the field of application.

Laser Powder Bed Fusion (LPBF) printing is used for manufacturing conformal cooling injection molds with internal cooling channels. Currently, the steel used to manufacture such molds by LPBF is the maraging 18Ni300. However, this steel is softer at high temperatures and less resistant to corrosion than the reference steel, the AISI H11. Moreover, 18Ni300 contains cobalt, an element that can be harmful to the health of people handling powders made of this steel. In order to find a cobalt-free alternative to 18Ni300, the printability of three different types of steel is studied: maraging stainless steels (CX, L40), martensitic non-stainless steels (42CD4, H11, H13, PM2012) and martensitic stainless steels (X15TN, PM420). The printability of those eight steels is studied through their mechanical properties (Rockwell hardness, Charpy impact test), their internal defects and surface roughness (X-ray tomography), the presence of cracks (optical microscope), and also through their microstructure (X-ray diffraction) in the as-built state. The results show that the stainless steels (PM420, X15TN, L40 and CX) exhibit interesting as-built properties allowing them to be considered as a possible alternative to the maraging steel 18Ni300 to produce LPBFed injection molds. A conformal cooling injection mold was then printed as a demonstrator.

In this paper, we present a novel process based on gas atomization and powder metallurgy techniques to produce reliable and stable (La1-zCez)(Fe1-x-yMnySix)(13)H-n materials, with 0.08 <= x <= 0.15, 0 <= y <= 0.05, 0 <= z <= 0.3 and 1.5 <= n <= 3. With this process, shaped pieces ready-to-use into refrigeration devices can be produced. Gas atomisation is a rapid solidification technique that prevents the La-Fe-Si-type alloy from forming very large alpha-Fe dendrites during cooling, allowing to easily and efficiently heat treat the obtained powder to form the magnetocaloric NaZn13-type intermetallic. In this process, a batch of 500 kg of alloy was first gas atomized into powder. The powder was then annealed at 1373 K under Ar for one hour to reach around 95% of magnetocaloric phase, and subsequently hydrogenated. Finally, the powder was shaped into composite shaped products containing 91.5 wt.% of powder, by extrusion. This process induces no loss of matter and allows producing non fragile pieces comprising thin portions. Our first results on the stability of partially hydrogenated (La,Ce)(Fe,Mn,Si)(13) materials are shown and we discuss on the possible existence of conditions of instability liked to both the composition of the magnetocaloric phase and the level of hydrogenation. (C) 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim