scholarly journals Effect of Scanning Strategy in the L-PBF Process of 18Ni300 Maraging Steel

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 826
Author(s):  
Francesco Rivalta ◽  
Lorella Ceschini ◽  
Anders E. W. Jarfors ◽  
Roland Stolt
Keyword(s):  
Laser Powder Bed Fusion ◽  
Scanning Strategy ◽  
Powder Bed ◽  
Maraging Steels ◽  
Material Hardness ◽  
Final Microstructure ◽  
Quench Cracking ◽  
Scanning Strategies ◽  
Powder Type ◽  
Physical And Chemical

Maraging steels are good candidates for the laser powder bed fusion process (L-PBF), also known as Selective Laser Melting, due to excellent weldability and resistance to quench cracking. Powders physical and chemical characteristics dominate the final microstructure and properties of the printed parts, that are also heavily influenced by the process parameters. In this study, the effects of the scanning strategies on dimensions, average surface roughness, density and material hardness were evaluated, keeping the powder type and the volumetric energy density (Andrew number) constant. The effects of the scanning strategy on these properties are far less understood than on other important ones, like residual stresses and distortion, strongly affected by the scanning strategy. In this study, parallel stripes, chessboard and hexagonal pattern strategies were studied, keeping the Andrew number constant but varying the interlayer rotation. In general, the hexagonal strategy underperformed compared to the chessboard and the stripes ones.

scholarly journals Study on laser powder bed fusion of nickel-base alloy of G-surface structure: scanning strategy, properties and compression properties

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Bo Qian ◽  
Hongri Fan ◽  
Jianrui Zhang ◽  
Tengfei Li ◽  
Jiangtao Xi ◽  
...  
Keyword(s):  
Surface Structure ◽  
Base Alloy ◽  
Nickel Base Alloy ◽  
Laser Powder Bed Fusion ◽  
Scanning Strategy ◽  
Powder Bed ◽  
Compression Performance ◽  
Solid Structure ◽  
Nickel Base ◽  
Scanning Strategies

AbstractAiming at laser powder bed fusion of GH3536 nickel base alloy, the effects of different scanning strategies on microstructure, porosity and mechanical properties were explored. In the aspect of microstructure and micro hardness of the sample, three scanning strategies had little difference; in the aspect of macro mechanical properties of the sample, the slope subarea scanning was better than the helix and island scanning. On this basis, the slope subarea scanning was selected as the optimal scanning strategy to form the G-surface structure, and the compression performance of G-surface was studied. The results showed that: (1) the compression performance of G-surface structure was smaller than that of solid structure, The compression strength of G-surface can only reach about 20% of solid structure: the average strength value of G-surface is 220 MPa, solid structure is 1.1 GMpa; while G-surface structure had a smooth compression curve, which indicated the good energy absorption characteristics; (2) with the increase of wall thickness, the mechanical performance of G-surface structure was also enhanced, while the energy absorption capacity was constantly reduced; (3) with the same wall thickness, the compression performance of sample in building direction (BD) is higher than that in horizontal direction (HD).

scholarly journals Study on Laser Powder Bed Fusion of Nickel-base Alloy: Scanning Strategy, Properties and Compression Properties

2020 ◽  
Author(s):  
Bo Qian ◽  
Hongri Fan ◽  
Tengfei Li ◽  
Jianrui Zhang ◽  
Jiangtao Xi ◽  
...  
Keyword(s):  
Surface Structure ◽  
Base Alloy ◽  
Powder Bed Fusion ◽  
Nickel Base Alloy ◽  
Laser Powder Bed Fusion ◽  
Scanning Strategy ◽  
Powder Bed ◽  
Compression Performance ◽  
Nickel Base ◽  
Scanning Strategies

Abstract Aiming at laser powder bed fusion of GH3536 nickel base alloy, the effects of different scanning strategies on microstructure, porosity and mechanical properties were explored. In the aspect of microstructure and micro hardness of the sample, three scanning strategies had little difference; in the aspect of macro mechanical properties of the sample, the slope subarea scanning was better than the helix and island scanning. On this basis, the slope subarea scanning was selected as the optimal scanning strategy to form the G-surface structure, and the compression performance of G-surface was studied. The results showed that: (1) the compression performance of G-surface structure was smaller than that of solid structure; while G-surface structure had a smooth compression curve, which indicated the good energy absorption characteristics; (2) with the increase of wall thickness, the mechanical performance of G-surface structure was also enhanced, while the energy absorption capacity was constantly reduced; (3) with the same wall thickness, the compression performance of sample in building direction (BD) is higher than that in horizontal direction (HD).

scholarly journals The residual stress in as-built Laser Powder Bed Fusion IN718 alloy as a consequence of the scanning strategy induced microstructure

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Itziar Serrano-Munoz ◽  
Tatiana Mishurova ◽  
Tobias Thiede ◽  
Maximilian Sprengel ◽  
Arne Kromm ◽  
...  
Keyword(s):  
Residual Stress ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Scanning Strategy ◽  
Powder Bed

scholarly journals Influence of Scanning Strategy on the Performances of GO-Reinforced Ti6Al4V Nanocomposites Manufactured by SLM

Metals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1379
Author(s):  
Xiaojin Miao ◽  
Xin Liu ◽  
Peipei Lu ◽  
Jitai Han ◽  
Weipeng Duan ◽  
...  
Keyword(s):  
Temperature Gradients ◽  
Experimental Results ◽  
Laser Melting ◽  
Scanning Strategy ◽  
Concentration Effects ◽  
Powder Bed ◽  
Simulation Results ◽  
Scanning Strategies ◽  
Matrix Nanocomposites ◽  
Simulation Scheme

In this work, the effects of line (L-scanning strategy), stripe (S-scanning strategy), hollow square (H-scanning strategy) and chess board partition (C-scanning strategy) on the performances of graphene oxide reinforced Ti6Al4V matrix nanocomposites (GO/TC4) as fabricated by selective laser melting (SLM) were investigated. Numerical temperature field simulation of four different scanning strategies was utilized to investigate the effects of thermal concentration on SLM-processed GO/TC4 nanocomposites, linking to its micro-voids, surface roughness, porosity, microhardness and tribological properties. The proposed simulation scheme is validated by comparing the simulated thermal analysis with experimental results. Simulation results show that the thermal concentration effects of a part during SLM process is distinctive under different scanning strategies, with the slowest cooling rate of 64,977.5 °C/s that is achieved by C-scanning strategy specimen. The experimental results indicate that the performances of the L-scanning strategy or S-scanning strategy sample are seriously affected by the thermal concentration, causing a large number of micro-voids and defects. All the experimental results suggest that the sample using C-scanning strategy exhibits the optimal performance of all investigated specimens, which closely correlates with its lowest temperature gradients. This study highlights the importance of using a partition scanning strategy during SLM process, which can be easily extended to other powder bed fusion process.

scholarly journals Scanning Strategies in the PBF Process: A Critical Review

2020 ◽  
Author(s):  
Ehsan Malekipour ◽  
Hazim El-Mounayri
Keyword(s):  
Residual Stress ◽  
Critical Review ◽  
Heat Accumulation ◽  
Scanning Strategy ◽  
Homogeneous Microstructure ◽  
Powder Bed ◽  
Pros And Cons ◽  
Scanning Strategies ◽  
Metallic Parts ◽  
Powder Fusion

Abstract The powder-bed fusion (PBF) process is capable of producing near-fully dense metallic parts; however, various defects — particularly thermal abnormalities — can still be observed during the process. Some of these thermal defects — cracks, distortion, delamination of layers, and microporosity — cannot be removed by post-processing operations. The majority of these abnormalities are the result of residual stress, heat accumulation, lack of inter-track /inter-layer bonding, lack of powder fusion, or a combination of these factors. Modifying the scanning strategy (the topology of scanning tracks) can efficiently mitigate these abnormalities by adjusting the process parameters and adopting proper scanning patterns. The implementation of different scanning strategies significantly changes the ultimate quality of printed parts and manufacturing process lead time. Choosing a proper scanning strategy minimizes the residual stress and internal porosity, generates homogeneous microstructure, and avoids heat accumulation throughout the part during the printing process. In this work, we conducted a critical review of different scanning strategies, their pros and cons, limitations, and influence on the resulting properties of fabricated parts. Furthermore, we report the latest efforts for improvement of the current scanning strategies and introduce the-state-of-the-art strategies in the multi-laser PBF (ML-PBF) process. The insights provided here can assist scholars in evaluating existing scanning strategies and scanning patterns, and in identifying ways both to overcome scanning limitations and to modify them. On the other hand, it can assist manufacturers in selecting the best scanning strategies for their products based on their designs, demands, and resources.

scholarly journals The study of the regularities of structure formation and properties of the L-PBF metal as a set of processes on the way to create a controlled structure

2020 ◽  
Vol 315 ◽  
pp. 13001
Author(s):  
Ivan Shakirov ◽  
Pavel Kuznetsov ◽  
Mikhail Staritsyn ◽  
Anton Zhukov ◽  
Vitaliy Bobyr
Keyword(s):  
Mechanical Properties ◽  
Structure Formation ◽  
Laser Power ◽  
Scanning Speed ◽  
Laser Powder Bed Fusion ◽  
Scanning Strategy ◽  
Powder Bed ◽  
Size And Morphology ◽  
Controlled Structure ◽  
The Relationship

In this work, to study the effect of laser powder bed fusion (L-PBF) parameters on the microstructure and mechanical properties of 321 austenitic steel, a series of samples were created combining various combinations of L-PBF technological modes, such as: laser spot diameter, scanning speed, laser power, scanning strategy. The possibility of controlling the structure formation of steel in the L-PBF process with the aim of obtaining a given crystallographic texture, grain size and morphology is estimated. The relationship between the resulting anisotropic structure and mechanical properties is investigated.

scholarly journals The Dimensional Accuracy of Thin-Walled Parts Manufactured by Laser-Powder Bed Fusion Process

2020 ◽  
Vol 4 (3) ◽  
pp. 91
Author(s):  
Josef Tomas ◽  
Leonhard Hitzler ◽  
Marco Köller ◽  
Jonas von Kobylinski ◽  
Michael Sedlmajer ◽  
...  
Keyword(s):  
Residual Stresses ◽  
Dimensional Accuracy ◽  
Powder Bed Fusion ◽  
Laser Powder Bed Fusion ◽  
Powder Bed ◽  
Cooling Channels ◽  
Thin Walled ◽  
Scanning Strategies ◽  
Different Diameters ◽  
Functional Components

Laser-Powder Bed Fusion brings new possibilities for the design of parts, e.g., cutter shafts with integrated cooling channels close to the contour. However, there are new challenges to dimensional accuracy in the production of thin-walled components, e.g., heat exchangers. High degrees of dimensional accuracy are necessary for the production of functional components. The aim is to already achieve these during the process, to reduce post-processing costs and time. In this work, thin-walled ring specimens of H13 tool steel are produced and used for the analysis of dimensional accuracy and residual stresses. Two different scanning strategies were evaluated. One is a stripe scan strategy, which was automatically generated and provided by the machine manufacturer, and a (manually designed) sectional scan strategy. The ring segment strategy is designed by manually segmenting the geometry, which results in a longer preparation time. The samples were printed in different diameters and analyzed with respect to the degree of accuracy and residual stresses. The dimensional accuracy of ring specimens could be improved by up to 81% with the introduced sectional strategy compared to the standard approach.

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