Comprehensive assessment of spatter material generated during selective laser melting of stainless steel

Obeidi, Muhannad Ahmed; Mussatto, Andre; Groarke, Robert; Vijayaraghavan, Rajani K.; Conway, Alex; Kaschel, F.R.; McCarthy, Éanna; Clarkin, Owen; O’Connor, Robert; Brabazon, Dermot

doi:10.1016/j.mtcomm.2020.101294

Cited by 33 publications

(14 citation statements)

References 32 publications

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“…However, larger agglomerated spatter particles were present within the recycled powder despite the inclusion of a two-stage sieving process, post fabrication. Spatter particles within AM powder has been shown within literature to have an unwanted impact on chemical composition [21]. The primary hypothesis to be determined from the study is the significance of performing frequent powder characterisation, throughout a recycling regime.…”

Section: Discussionmentioning

confidence: 99%

Reuse of Grade 23 Ti6Al4V Powder during the Laser-Based Powder Bed Fusion Process

Harkin

Nikam

et al. 2020

Metals

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Titanium alloy powder used for laser-based powder bed fusion (L-PBF) process is costly. One of the solutions is the inclusion of a powder recycling strategy, allowing unused or exposed powder particles to be recuperated post manufacture, replenished and used for future builds. However, during a L-PBF process, powder particles are exposed to high levels of concentrated energy from the laser. Particularly those in close proximity to the melt pool, leading to the formation of spatter and agglomerated particles. These particles can settle onto the powder bed, which can then influence the particle size distribution and layer uniformity. This study analysed extra-low interstitial (ELI) Ti6Al4V (Grade 23) powder when subjected to nine recycle iterations, tracking powder property variation across the successive recycling stages. Characterisation included chemical composition focusing upon O, N, and H content, particle size distribution, morphology and tapped and bulk densities. On review of the compositional analysis, the oxygen content exceeded the 0.13% limit for the ELI grade after 8 recycles, resulting in the degradation from Grade 23 level.

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Section: Discussionmentioning

confidence: 99%

Reuse of Grade 23 Ti6Al4V Powder during the Laser-Based Powder Bed Fusion Process

Harkin

Nikam

et al. 2020

Metals

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“…Another defect could be spatter that occurs with high energy inputs, and details are provided in the Figure 9. Spatter occurs when the metal vapor force overcomes the surface tension force and it is difficult to be melted in the next layers; usually spatters are larger than powder size, and would remain as inclusions [42]. Keyholes are one of the most common defects with high energy inputs, which are a result of the vaporization of metal [38].…”

Section: Experimental Confirmationmentioning

confidence: 99%

Selective Laser Melting of 316L Austenitic Stainless Steel: Detailed Process Understanding Using Multiphysics Simulation and Experimentation

Ansari

Rehman

Pıtır

et al. 2021

Metals

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The parameter sets used during the selective laser melting (SLM) process directly affect the final product through the resulting melt-pool temperature. Achieving the optimum set of parameters is usually done experimentally, which is a costly and time-consuming process. Additionally, controlling the deviation of the melt-pool temperature from the specified value during the process ensures that the final product has a homogeneous microstructure. This study proposes a multiphysics numerical model that explores the factors affecting the production of parts in the SLM process and the mathematical relationships between them, using stainless steel 316L powder. The effect of laser power and laser spot diameter on the temperature of the melt-pool at different scanning velocities were studied. Thus, mathematical expressions were obtained to relate process parameters to melt-pool temperature. The resulting mathematical relationships are the basic elements to design a controller to instantly control the melt-pool temperature during the process. In the study, test samples were produced using simulated parameters to validate the simulation approach. Samples produced using simulated parameter sets resulting in temperatures of 2000 K and above had acceptable microstructures. Evaporation defects caused by extreme temperatures, unmelted powder defects due to insufficient temperature, and homogenous microstructures for suitable parameter sets predicted by the simulations were obtained in the experimental results, and the model was validated.

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“…It can also be released from gas inclusions within the powder [ 4 ]. The inclusions result from the gas atomization production of the powder or from spatter particles, which can appear in reused powder [ 5 ]. Larger gas pores result from instabilities in the keyhole.…”

Section: Introductionmentioning

confidence: 99%

Methodology to Determine Melt Pool Anomalies in Powder Bed Fusion of Metals Using a Laser Beam by Means of Process Monitoring and Sensor Data Fusion

et al. 2022

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Additive manufacturing, in particular the powder bed fusion of metals using a laser beam, has a wide range of possible technical applications. Especially for safety-critical applications, a quality assurance of the components is indispensable. However, time-consuming and costly quality assurance measures, such as computer tomography, represent a barrier for further industrial spreading. For this reason, alternative methods for process anomaly detection using process monitoring systems have been developed. However, the defect detection quality of current methods is limited, as single monitoring systems only detect specific process anomalies. Therefore, a new methodology to evaluate the data of multiple monitoring systems is derived using sensor data fusion. Focus was placed on the causes and the appearance of defects in different monitoring systems (photodiodes, on- and off-axis high-speed cameras, and thermography). Based on this, indicators representing characteristics of the process were developed to reduce the data. Finally, deterministic models for the data fusion within a monitoring system and between the monitoring systems were developed. The result was a defect detection of up to 92% of the melt track defects. The methodology was thus able to determine process anomalies and to evaluate the suitability of a specific process monitoring system for the defect detection.

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Comprehensive assessment of spatter material generated during selective laser melting of stainless steel

Cited by 33 publications

References 32 publications

Reuse of Grade 23 Ti6Al4V Powder during the Laser-Based Powder Bed Fusion Process

Reuse of Grade 23 Ti6Al4V Powder during the Laser-Based Powder Bed Fusion Process

Selective Laser Melting of 316L Austenitic Stainless Steel: Detailed Process Understanding Using Multiphysics Simulation and Experimentation

Methodology to Determine Melt Pool Anomalies in Powder Bed Fusion of Metals Using a Laser Beam by Means of Process Monitoring and Sensor Data Fusion

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