Powder bed fusion of metals using a laser beam system (PBF-LB/M) of highly complex and filigree parts made of tool steels is becoming more important for many industrial applications and scientific investigations. To achieve high density and sufficient chemical homogeneity, pre-alloyed gas-atomized spherical powder feedstock is used. For high-performance materials such as tool steels, the number of commercially available starting powders is limited due to the susceptibility to crack formation in carbon-bearing steels. Furthermore, scientific alloy development in combination with gas-atomization is a cost-intensive process which requires high experimental effort. To overcome these drawbacks, this investigation describes the adaption of a hot work tool steel for crack-free PBF-LB/M-fabrication without any preheating as well as an alternative alloying strategy which implies the individual admixing of low-cost aspherical elemental powders and ferroalloy particles with gas-atomized pure iron powder. It is shown that the PBF-LB/M-fabrication of this powder mixture is technically feasible, even though the partly irregular-shaped powder particles reduce the flowability and the laser reflectance compared to a gas-atomized reference powder. Moreover, some high-melting alloying ingredients of the admixed powder remain unmolten within the microstructure. To analyze the laser energy input in detail, the second part of the investigation focuses on the characterization of the individual laser light reflectance of the admixed alloy, the gas-atomized reference powder and the individual alloying elements and ferroalloys.

The analysis of surface effects in powder bed fusion additive manufacturing is the subject of intensive research activities. The aim of this paper is to provide an overview of the current state of knowledge and to gain a comprehensive understanding of this subject area. The paper is intended to enable researchers to select specific articles for their own further research context. In addition, a bibliometric analysis validates the data base. A discussion of the findings suggests that the criticality of the surface should be considered as a quality factor in the field of additive manufacturing by powder bed fusion processes. An accurate and reliable measurement is crucial for predicting component quality. There is a clear trend from two-dimensional measurements to three-dimensional measurements. Conducting comprehensive research is essential to improve the reliability and comparability of measurement results and to promote broad acceptance and application of this technology in the industry.

The powder bed fusion of metals using a laser beam (PBF-LB/M) is an additive manufacturing process for the direct production of metal parts using powder as a starting material. The PBF-LB/M process consists of two main steps: the application of a new powder layer and the melting of the cross-sections of the parts in each layer. Laser exposure usually takes up a lot of time during a build process; however, the application of powder layers, also taking up a considerable amount of time, offers potential to shorten production times. In this work, a powder test rig that mimics the real flow conditions of a PBF-LB/M system is used to measure the quality of X3NiCoMoTi18-9-5 powder layers applied at different recoater speeds by determining the powder surface roughness. The same recoating settings are then used on a real PBF-LB/M system to produce samples and investigate their densities as a function of recoater speed. The results show that the recoater speed influences the surface of the applied powder bed and has an effect on the density of the manufactured samples. However, this influence decreases if only samples with a high relative density are considered.

Powder bed fusion of metals using a laser beam (PBF‐LB/M) is an additive manufacturing process for the direct production of metallic components using metal powder as a starting material. In order to improve the properties of the PBF‐LB/M components and increase the process efficiency by improving the laser absorption and the flowability of the metal powders used, powders are additivated with nanoparticles prior to processing by PBF‐LB/M in the literature. In the present work, X2CrNiMo17‐12‐2 (1.4404/316L) powder coated with silicon carbide (SiC), silicon (Si), and silicon nitride (Si₃N₄) nanoparticles in volume fractions of 0.25–1 vol% is processed by PBF‐LB/M. Initially, multilayer single tracks (MST) are produced. In the next step, dynamic hatch (DH) samples are manufactured based on the MST tests. The coating of the powder feedstock with nanoparticles leads to an enlargement of the process window in the DH test and an increase in the maximum build rate.

Powder bed fusion of metals using a laser beam (PBF-LB/M) is an established additive manufacturing (AM) method that can be used to fabricate geometrically complex Nd-Fe-B magnets. However, the magnetic properties of Nd-Fe-B magnets manufactured by PBF-LB/M are typically inferior to conventionally produced magnets. To overcome this drawback, we modified the surface of the permanent magnet feedstock powder with 1 wt.% surfactant-free Ag nanoparticles (NPs) supporting the formation of relevant phases required for permanent magnetic performance to achieve a suitable micro- and nanostructure after AM. Our study is accompanied by finite element simulations, revealing the impact and dependency of process parameters during PBF-LB/M: a wide temperature field with a high-gradient profile in the front and on the bottom of an overheated region, implying a vast local heating/cooling rate and in-process high thermal stress. We found experimentally that the as-built part density can be affected by both the laser power and scan speed, causing a reduction in density as both parameters increase. The functionality and microstructural properties are also investigated via VSM, HR-SEM, EDX, EBSD, and exemplarily with HR-TEM-EDX and APT. Our study found that modifying MQP-S with Ag NPs increases the coercivity by approximately 20%, which we correlate to a decreased grain size. Additionally, we identified three distinct phases in the modified and unmodified samples, where Ag is primarily found in the intergranular and Nd-rich phases of the as-built parts. Overall, the study's findings contribute to the understanding of the factors that affect the quality and magnetic properties of Nd-Fe-B magnets fabricated through PBF-LB/M and provide valuable insights for further research in this area.