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Materials Science in Additive Manufacturing SLM of ODS steel: Process and properties

to ensure the consistency and stability of the material’s properties were assessed within the anticipated operational
quality. temperature range. This study will serve as a basis for
In addition to mechanical alloying, soft-mixing subsequent studies aimed at studying the specifics of the
techniques are employed to produce ODS steels by SLM. production of high chromium ferritic-martensitic ODS
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This approach facilitates uniform adhesion of oxide steels.
particles onto the surface of steel powders, in contrast 2. Materials and methods
to alloying processes involving dispersed particles of the
matrix material. By maintaining the original spherical 2.1. Materials
morphology of the powder particles, the soft-mixing In this study, ferritic-martensitic steel powder with the
method ensures good flowability. The advantage of this chemical composition presented in Table 1 was employed
method of powder preparation is the relatively simple as the base material. The base gas atomized ferritic/
and fast mixing process compared with mechanical martensitic steel powder had a particle size distribution of
alloying. Zhai et al. investigated the influence of 22 – 63 μm.
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interface wettability of 316L ODS steel strengthened by
Y O on tensile properties. Poor interface wettability of For the production of ODS steel through SLM, the
3
2
the nanoparticles and the basic steel was the reason for base steel powder was mixed with 0.25 wt.% Y O using
3
2
the Y O agglomerations forming, which led to internal an acoustic mixing process. The acoustic mixing process
2
3
defects. Besides, the increases in yield strength (YS) and was performed on a laboratory unit. The particle size
ultimate tensile strength (UTS) were neglectable, and the distribution study was carried out on an Analysette 22
nanoparticle agglomeration significantly decreased the NanoTec plus analyzer (Fritsch GmbH, Idar-Oberstein,
elongation. The results of the investigation and comparison Germany) operating in the particle measurement range
of tensile properties and tribological behavior of the from 0.01 to 2000 μm. The flowability of the powder was
two alloys (basic and ODS) fabricated by SLM showed a determined using a Hall flowmeter.
significant reduction in wear rate (by 51%) when 0.3 wt.% 2.2. SLM and heat treatment
Y O nanoparticles were added compared to the matrix
2
3
alloy. 1 The SLM process was performed on a 3DLAM Mid
system (Biograd CJSC, St. Petersburg, Russia) equipped
The acoustic mixing method has been successfully with a platform pre-heating module capable of achieving
utilized to achieve a uniform distribution of oxides in a temperatures up to 300°C and a laser with a maximum
NiCoCr medium-entropy alloy. The introduction of 1 output power of 500 W. To optimize the process parameters,
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wt.% Y O led to a significant enhancement in mechanical two sets of samples were fabricated: One without the
2
3
properties, as confirmed by tensile testing. Notably, the platform pre-heating and another with the platform pre-
addition of Y O resulted in a marked improvement heating of 300°C. Each set comprised 20 cubic samples
3
2
in strength, particularly at elevated temperatures, (10 mm × 10 mm × 10 mm) produced directly on the
highlighting the efficacy of this approach in optimizing baseplate without supporting structures. Scanning speed
high-temperature performance. and laser power were systematically varied, while the
Presently, the details of AM processes of high chromium hatching distance was maintained at 120 μm, and the layer
ferritic/martensitic steels remain underexplored. These thickness was fixed at 30 μm. The applied SLM process
steels are susceptible to cracking, which complicates their parameters are detailed in Table 2. A stripe-hatching
production by methods such as SLM. There are virtually pattern with a 67° rotation between layers was employed
no studies devoted to the investigation of the production of to enhance mechanical properties and minimize residual
ODS steels based on high-chromium ferritic/martensitic stresses. 29
steels, despite their promising application in nuclear power Since the energy input to the material significantly
engineering. affects melt pool formation and the properties of the

This research is aimed at studying the possibilities resulting structure, the volumetric energy density
3
of fabrication of ferritic/martensitic ODS steel by SLM (VED, J/mm ) was calculated using the following equation:
and analyzing the structure and tensile properties of the VED = P/(v × h × t), (I)
obtained material, including at elevated temperatures
(720°C). The present study also employed platform pre- where P = laser power (W); v = scanning speed (mm/s);
heating as a method to mitigate cracking and enhance h = hatch distance (mm); and t = layer thickness (mm).
material density. Given the significance of this steel in the The typical heat treatment mode for this material
context of next-generation reactor applications, the tensile involves quenching at 1050 – 1100°C for 30 min, followed

Volume 4 Issue 1 (2025) 3 doi: 10.36922/MSAM025060004