scholarly journals Comparison of the Processability and Influence on the Microstructure of Different Starting Powder Blends for Laser Powder Bed Fusion of a Fe3.5Si1.5C Alloy

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1107
Author(s):  
Anna Luise Strauch ◽  
Volker Uhlenwinkel ◽  
Matthias Steinbacher ◽  
Felix Großwendt ◽  
Arne Röttger ◽  
...  
Keyword(s):  
Base Material ◽  
Model Alloy ◽  
Dissolution Behavior ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Alloy Development ◽  
Chemical Homogeneity ◽  
Powder Bed ◽  
Fe Powder ◽  
Powder Blends

This paper examines different blends of starting materials for alloy development in the laser powder bed fusion (LPBF) process. By using blends of individual elemental, ferroalloy and carbide powders instead of a pre-alloyed gas-atomized starting powder, elaborate gas-atomization processes for the production of individual starting powders with varying alloy compositions can be omitted. In this work the model alloy Fe3.5Si1.5C is produced by LPBF from different blends of pure elemental, binary and ternary powders. Three powder blends were processed. The base material for all powder blends is a commercial gas-atomized Fe powder. In the first blend this Fe powder is admixed with SiC, in the second with the ternary raw alloy FeSiC and in the third with FeSi and FeC. After characterizing the powder properties and performing LPBF parameter studies for each powder blend, the microstructures and the mechanical properties of the LPBF-manufactured samples were analyzed. Therefore, investigations were carried out by scanning electron microscopy, wave length dispersive x-ray spectroscopy and micro hardness testing. It was shown that the admixed SiC dissolves completely during LPBF. But the obtained microstructure consisting of bainite, martensite, ferrite and retained austenite is inhomogeneous. The use of the lower melting ferroalloys FeSi and FeC as well as the ternary ferroalloy FeSiC leads to an increased chemical homogeneity after LPBF-processing. However, the particle size of the used components plays a decisive role for the dissolution behavior in LPBF.

scholarly journals Rapid Alloy Development of Extremely High-Alloyed Metals Using Powder Blends in Laser Powder Bed Fusion

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1706 ◽  
Author(s):  
Simon Ewald ◽  
Fabian Kies ◽  
Steffen Hermsen ◽  
Maximilian Voshage ◽  
Christian Haase ◽  
...  
Keyword(s):  
Microstructural Characterization ◽  
Chemical Compositions ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Alloy Development ◽  
Large Space ◽  
Powder Bed ◽  
High Entropy ◽  
Powder Blends ◽  
Rapid Alloy Development

The design of new alloys by and for metal additive manufacturing (AM) is an emerging field of research. Currently, pre-alloyed powders are used in metal AM, which are expensive and inflexible in terms of varying chemical composition. The present study describes the adaption of rapid alloy development in laser powder bed fusion (LPBF) by using elemental powder blends. This enables an agile and resource-efficient approach to designing and screening new alloys through fast generation of alloys with varying chemical compositions. This method was evaluated on the new and chemically complex materials group of multi-principal element alloys (MPEAs), also known as high-entropy alloys (HEAs). MPEAs constitute ideal candidates for the introduced methodology due to the large space for possible alloys. First, process parameters for LPBF with powder blends containing at least five different elemental powders were developed. Secondly, the influence of processing parameters and the resulting energy density input on the homogeneity of the manufactured parts were investigated. Microstructural characterization was carried out by optical microscopy, electron backscatter diffraction (EBSD), and energy-dispersive X-ray spectroscopy (EDS), while mechanical properties were evaluated using tensile testing. Finally, the applicability of powder blends in LPBF was demonstrated through the manufacture of geometrically complex lattice structures with energy absorption functionality.

scholarly journals Laser Powder-Bed Fusion as an Alloy Development Tool: Parameter Selection for In-Situ Alloying Using Elemental Powders

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3922
Author(s):  
Leonardo Shoji Aota ◽  
Priyanshu Bajaj ◽  
Hugo Ricardo Zschommler Sandim ◽  
Eric Aimé Jägle
Keyword(s):  
Process Parameters ◽  
Research Field ◽  
Beam Diameter ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Alloy Development ◽  
Chemical Homogeneity ◽  
Powder Mixtures ◽  
Powder Bed

The design of advanced alloys specifically tailored to additive manufacturing processes is a research field that is attracting ever-increasing attention. Laser powder-bed fusion (LPBF) commonly uses pre-alloyed, fine powders (diameter usually 15–45 µm) to produce fully dense metallic parts. The availability of such fine, pre-alloyed powders reduces the iteration speed of alloy development for LPBF and renders it quite costly. Here, we overcome these drawbacks by performing in-situ alloying in LPBF starting with pure elemental powder mixtures avoiding the use of costly pre-alloyed powders. Pure iron, chromium, and nickel powder mixtures were used to perform in-situ alloying to manufacture 304 L stainless steel cube-shaped samples. Process parameters including scanning speed, laser power, beam diameter, and layer thickness were varied aiming at obtaining a chemically homogeneous alloy. The scientific questions focused on in this work are: which process parameters are required for producing such samples (in part already known in the state of the art), and why are these parameters conducive to homogeneity? Analytical modelling of the melt pool geometry and temperature field suggests that the residence time in the liquid state is the most important parameter controlling the chemical homogeneity of the parts. Results show that in-situ alloying can be successfully employed to enable faster and cost-efficient rapid alloy development.

High strength Al alloy development for laser powder bed fusion

2021 ◽  
pp. 2141001
Author(s):  
Jin’e Sun ◽  
Baicheng Zhang ◽  
Xuanhui Qu
Keyword(s):  
High Strength ◽  
Nucleation Site ◽  
Al Alloys ◽  
Hot Tearing ◽  
Al Alloy ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Alloy Development ◽  
Powder Bed ◽  
Columnar Grain

High strength Al alloy development is the key technique to additive manufacturing (AM) applied on lightweight of aerospace, automotive and military industry. Unlike the conventional wrought Al–Si eutectic alloys available for AM process, the strength of new developed Al alloy can be improved by in situ or additional nano-precipitated phase. This paper presents an overview of high strength Al alloys development including metallic additives, such as Zr, Sc, Mn, Cu, etc., and nanoparticle additives, such as ceramics (TiB2, TiC, LaB6 and TiN) as well as carbon nanotubes (CNTs). The addition of Zr and Sc elements significantly prevents hot tearing and enhances the strength of laser processed Al alloys because the nanoscale Al3Zr, Al3Sc and Al3 (Sc, Zr) precipitated phases generate, facilitate the heterogeneous nucleation of Al matrix and refine the microstructure. Moreover, the addition of Mn and Cu elements provides an increment in the toughness and strength of laser processed Al alloys through the superimposed effect of multi-element solid solution reinforcement and precipitation strengthening role of some Al2CuMg and Al6Mn. The growth process of Al alloy can be interrupted by the addition of nanoceramics particles as additional nucleation site which leads the columnar grain transforms to the equiaxed grain. Furthermore, the mechanism of mutual solubility of LaB6, TiB2, TiC and TiN in Al alloys is systematically studied. Finally, an assessment of the state in laser processed high strength Al alloys and the research demands for the expansion of laser powder bed fusion of Al metallic components are provided.

scholarly journals Effect of bimodal powder blends on part density and melt pool fluctuation in laser powder bed fusion

2021 ◽  
Author(s):  
Lukas Haferkamp ◽  
Simon Liechti ◽  
Adriaan Spierings ◽  
Konrad Wegener
Keyword(s):  
Volume Fraction ◽  
Final Part ◽  
Powder Particle Size ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Coarse Powder ◽  
Powder Bed ◽  
Melt Pool ◽  
Powder Blends ◽  
Part Density

AbstractThe final part density in laser powder bed fusion is influenced by the powder particle size distribution. Too fine powders are not spreadable, and too coarse powders cause porosity. Powder blends, especially bimodal ones, can exhibit higher packing densities and changes in flowability compared to their monomodal constituents. These properties can influence final part density. Therefore, the influence of bimodal powder on final part density was investigated. Two gas atomized 316L (1.4404) powders with a D50 of 20.3 µm and 60.3 µm were blended at weight ratios of 3:1, 1:1, and 1:3, and the original and blended powders were processed. The results show that the final part porosity increases almost linearly with an increasing volume fraction of coarse powder. Furthermore, the final part density is independent of powder bulk density and flowability. Measurements of the top surface show that an increase of part porosity by coarse powder is caused by an increase in melt pool fluctuation, which in turn causes irregular solidified scan tracks. Additionally, the results show that the powder segregation during coating is stronger for the bimodal powder; however, no influence of the segregation on the part density could be found.

High strength Al-Li alloy development for laser powder bed fusion

2021 ◽  
pp. 102249
Author(s):  
Yang Qi ◽  
Zhiheng Hu ◽  
Hu Zhang ◽  
Xiaojia Nie ◽  
Changchun Zhang ◽  
...  
Keyword(s):  
High Strength ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Alloy Development ◽  
Powder Bed

scholarly journals On the Relevance of Volumetric Energy Density in the Investigation of Inconel 718 Laser Powder Bed Fusion

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 538 ◽  
Author(s):  
Fabrizia Caiazzo ◽  
Vittorio Alfieri ◽  
Giuseppe Casalino
Keyword(s):  
Surface Roughness ◽  
Energy Density ◽  
Process Parameters ◽  
Vickers Hardness ◽  
Powder Bed Fusion ◽  
Processing Conditions ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Fractional Density ◽  
Experimental Variation

Laser powder bed fusion (LPBF) can fabricate products with tailored mechanical and surface properties. In fact, surface texture, roughness, pore size, the resulting fractional density, and microhardness highly depend on the processing conditions, which are very difficult to deal with. Therefore, this paper aims at investigating the relevance of the volumetric energy density (VED) that is a concise index of some governing factors with a potential operational use. This paper proves the fact that the observed experimental variation in the surface roughness, number and size of pores, the fractional density, and Vickers hardness can be explained in terms of VED that can help the investigator in dealing with several process parameters at once.

Heat source model calibration for thermal analysis of laser powder-bed fusion

2020 ◽  
Vol 106 (7-8) ◽  
pp. 3367-3379 ◽  
Author(s):  
Shahriar Imani Shahabad ◽  
Zhidong Zhang ◽  
Ali Keshavarzkermani ◽  
Usman Ali ◽  
Yahya Mahmoodkhani ◽  
...  
Keyword(s):  
Thermal Analysis ◽  
Heat Source ◽  
Model Calibration ◽  
Source Model ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Heat Source Model ◽  
Powder Bed
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