Characterization of 17-4PH Single Tracks Produced at Different Parametric Conditions towards Increased Productivity of LPBF Systems—The Effect of Laser Power and Spot Size Upscaling

Makoana, Nkutwane Washington; Yadroitsava, Ina; Möller, Heinrich; Yadroitsev, Igor

doi:10.3390/met8070475

Cited by 43 publications

(20 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…In addition to studying the full LPBF process to realize parts and samples for tensile and fatigue tests, single-track experiments are extensively used to understand the powder-laser interaction [48][49][50][51]. These experiments allow highlighting the presence of stability zones, where the track is continuous, and instability zones, whose irregularities (i.e., distortions, balling) are highly dependent on the scanning speed values, on the laser power, on the thickness of the powder layer and the substrate material on which it is spread, and on the powder particle morphology and granulometry [33,42,46,48,[52][53][54].…”

Section: The Lpbf Processmentioning

confidence: 99%

“…The connection between the shape of the laser beam profile and the melt pool was extensively studied in the literature [51,91,92]. Furthermore, the top-hat shape employed in laser welding [93] was shown to produce keyholes having a shorter depth and, for this reason, Tenbrock et al [94] recently applied this profile in laser powder bed fusion of 316 L stainless steel, showing that an efficient LPBF processes can also be realized by applying diode lasers as long as a proper defined intensity threshold is exceeded (I ≈ 8-10 × 10 5 W/cm 2 [94]).…”

Section: Heat Sourcementioning

confidence: 99%

See 1 more Smart Citation

Material Reuse in Laser Powder Bed Fusion: Side Effects of the Laser—Metal Powder Interaction

Santecchia

Spigarelli

Cabibbo

2020

Metals

View full text Add to dashboard Cite

Metal additive manufacturing is changing the way in which engineers and designers model the production of three-dimensional (3D) objects, with rapid growth seen in recent years. Laser powder bed fusion (LPBF) is the most used metal additive manufacturing technique, and it is based on the efficient interaction between a high-energy laser and a metal powder feedstock. To make LPBF more cost-efficient and environmentally friendly, it is of paramount importance to recycle (reuse) the unfused powder from a build job. However, since the laser-powder interaction involves complex physics phenomena and generates by-products which might affect the integrity of the feedstock and the final build part, a better understanding of the overall process should be attained. The present review paper is focused on the clarification of the interaction between laser and metal powder, with a strong focus on its side effects. Figure 1. Schematics of the laser powder bed fusion (LPBF) equipment. Adapted from Reference [9] with permission from Elsevier.While the market and the applications of laser powder bed fusion continuously and impressively grew in recent years, there is a common view across users and researchers concerning the repeatability of the process in terms of chemical composition and mechanical properties of the final parts, which are of paramount importance when challenging environmental or testing conditions are considered [10][11][12][13][14][15][16].The most typical approach to study the microstructural and mechanical properties of parts built by LPBF is to compare them with castings of the same alloy or, rather, the corresponding alloy since the starting material is metal powder rather than a fuse. However, in some existing alloys designed for cast and wrought parts, laser additive manufacturing processing results in cracking or other microstructure deficiencies [11,12,16,17]. It is worth noting that LPBF has more similarities with laser welding rather than casting, since the two laser-based techniques have some common features (i.e., melt-pool formation, moving heat source) [18]. However, process parameters are, in general, quite different in terms of laser power and scan speed, and the laser-matter interaction is much more complicated in LPBF processes, since the powder feedstock is inherently unstable and the solidified material undergoes multiple thermal cycles corresponding to the fusion of subsequent layers during the additive process [19][20][21][22]. Furthermore, owing to the similarities with welding and to the complicated interaction between laser and metal particles, when comparing laser powder bed fusion with other metal forming processes, it is evident that the range of processable alloys is very limited and the number of high-productivity commercially available alloys is even smaller [23]. One of the reasons behind this is that the level of metal powder sensitivity to the laser action during LPBF is not yet fully understood, despite the efforts of the scientific community to uncover it [24][25][26][27], and ...

show abstract

Section: The Lpbf Processmentioning

confidence: 99%

Section: Heat Sourcementioning

confidence: 99%

Material Reuse in Laser Powder Bed Fusion: Side Effects of the Laser—Metal Powder Interaction

Santecchia

Spigarelli

Cabibbo

2020

Metals

View full text Add to dashboard Cite

show abstract

“…This allowed for the application of a wide processing window, with E V in the range between 60 and 240 J mm −3 for the investigated alloying system. A higher energy input resulted in higher homogeneity of the elemental distribution due to enlargement of the melt pool size by means of width and depth, which resulted in a higher number of powder particles in the melt pool [36]. The calculated particle amount contained in the melt pools shown in Figure 5 was 15 for Figure 5b, 57 for Figure 5d, and 386 for Figure 5f.…”

Section: Discussionmentioning

confidence: 99%

“…In Figure 6a, partially molten particles and heterogeneously composed areas can be found. Furthermore, the increased energy input also promoted higher homogeneity due to a higher melt pool temperature [36]. As a consequence, less nonfused material was observed (Figure 5 and Figure 6).…”

Section: Discussionmentioning

confidence: 99%

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

et al. 2019

View full text Add to dashboard Cite

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.

show abstract

“…Beam quality, power density, and intensity profile all influence LPBF processing quality. Yadroitsev et al, Makoana et al, and Shi et al showed that in LPBF, the width of the tracks is primarily defined by spot size and laser power [7][8][9]. During laser processing, the diameter of the laser beam defines the power density and, as a result, geometrical characteristics of single tracks.…”

Section: Laser Beam Characteristicsmentioning

confidence: 99%

Influence of optical system operation on stability of single tracks in selective laser melting

Zhirnov¹,

Yadroitsev²,

Lane³

et al. 2019

Self Cite

View full text Add to dashboard Cite

Additive manufacturing (AM) technologies are increasingly being studied and introduced into the modern industry, but for wide applications there exists some "lack of confidence" about the quality of the parts produced by AM. This distrust has an objective basis: it was shown that the final 3D object is a superposition of a huge number of tracks and layers, and deviations from the optimal process parameters can lead to non-regular shape, unmelted places (lack of fusion) and porosity. Experiments with different bare substrates were performed to classify instabilities and artifacts in single tracks derived from laser beam characteristics, the optical system, scanning strategy, etc. demonstrating an adjustment scheme for testing and verifying LPBF equipment. An important point is that this research can be useful for the custom experimental setup. The paper describes the importance of checking the system before each build to identify problems caused by optical system operation. Also, possible deviations from the stable process, methods of their diagnostics and solutions are described. The proposed method is a cost-free way to diagnose the stability of the selective laser melting, which does not imply the necessity of having additional systems for detecting problems. The diagnostic scheme was used to evaluate in situ diagnostics of the LPBF processes on the Additive Manufacturing Metrology Testbed (AMMT) at the National Institute of Standards and Technology (NIST).

show abstract

Characterization of 17-4PH Single Tracks Produced at Different Parametric Conditions towards Increased Productivity of LPBF Systems—The Effect of Laser Power and Spot Size Upscaling

Cited by 43 publications

References 24 publications

Material Reuse in Laser Powder Bed Fusion: Side Effects of the Laser—Metal Powder Interaction

Material Reuse in Laser Powder Bed Fusion: Side Effects of the Laser—Metal Powder Interaction

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

Influence of optical system operation on stability of single tracks in selective laser melting

Contact Info

Product

Resources

About