Understanding keyhole induced-porosities in laser powder bed fusion of aluminum and elimination strategy

Guo, Liping; Wang, Hongze; Liu, Hanjie; Huang, Yuze; Wei, Qianglong; Leung, Chu Lun Alex; Wu, Yi; Wang, Haowei

doi:10.1016/j.ijmachtools.2022.103977

Cited by 30 publications

(3 citation statements)

References 31 publications

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“…When maintaining a constant laser power of 260 W, the melt pool for both the bare plate and powder plate transitions from a keyholing mode to a conduction mode as the laser speed increases from 0.52 m/s to 2.20 m/s, shown in Figure 4(a1-e1,a2-e2). This transition is judged by the increase in the width-to-depth ratio, where the start of keyholing has typically been identified when the ratio is less than 1 [12][13][14]20,63]. This transition occurs because the decreasing laser energy deposition is insufficient to sustain the laser penetration [11][12][13]19,61].…”

Section: Melt Pool Surface Topography and Dimensions In The Single-tr...mentioning

confidence: 99%

Understanding Melt Pool Behavior of 316L Stainless Steel in Laser Powder Bed Fusion Additive Manufacturing

Zhang,

Sun

et al. 2024

Micromachines

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In the laser powder bed fusion additive manufacturing process, the quality of fabrications is intricately tied to the laser–matter interaction, specifically the formation of the melt pool. This study experimentally examined the intricacies of melt pool characteristics and surface topography across diverse laser powers and speeds via single-track laser scanning on a bare plate and powder bed for 316L stainless steel. The results reveal that the presence of a powder layer amplifies melt pool instability and worsens irregularities due to increased laser absorption and the introduction of uneven mass from the powder. To provide a comprehensive understanding of melt pool dynamics, a high-fidelity computational model encompassing fluid dynamics, heat transfer, vaporization, and solidification was developed. It was validated against the measured melt pool dimensions and morphology, effectively predicting conduction and keyholing modes with irregular surface features. Particularly, the model explained the forming mechanisms of a defective morphology, termed swell-undercut, at high power and speed conditions, detailing the roles of recoil pressure and liquid refilling. As an application, multiple-track simulations replicate the surface features on cubic samples under two distinct process conditions, showcasing the potential of the laser–matter interaction model for process optimization.

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Section: Melt Pool Surface Topography and Dimensions In The Single-tr...mentioning

confidence: 99%

Understanding Melt Pool Behavior of 316L Stainless Steel in Laser Powder Bed Fusion Additive Manufacturing

Zhang,

Sun

et al. 2024

Micromachines

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“…Aluminum, characterized by one of the lowest emissivity values among metals, presents challenges in the laser focus zone, leading to increased reflectivity resulting from the physical-chemical characteristics of the metal. Solving this problem involves carefully adjusting the powder roughness and particle size distribution 5 . In the laser powder bed fusion system, an integral step involves uniformly depositing successive layers of powder and subsequently exposing them to laser radiation, whereby the surface interacts through molten pools to construct an enclosing surface 6 .…”

Section: Introductionmentioning

confidence: 99%

Influence of Moisture on the Properties of AlSi10Mg Powder for Laser Powder Bed Fusion

Peres,

Gargarella,

Paiva

et al. 2024

Mat. Res.

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This study explores the behavior of aluminum powder in laser powder bed fusion (LPBF) for additive manufacturing. Focusing on AlSi10Mg powders, the research investigates the effects of environmental conditions, such as temperature and humidity, on crucial properties like moisture content, fluidity, density, and agglomeration. Comprehensive tests, including particle size analysis and fluidity assessments, were conducted. Results showed increased flow time in the Carney funnel fluidity test after storage, but flow properties were maintained under high-temperature, low-humidity conditions. High humidity led to recurrent agglomerate formation. Moisture content analysis aligned with literature findings. Conclusively, these tests provide a reference for material acceptance and aid in supplier comparison for improved machine fluidity. While temperature and humidity impact aluminum oxide formation, humidity's greater relevance affects powder fluidity and quality. Other factors mentioned may cause permanent damage to the aluminum powder.

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“…These porosities caused by the keyhole can lead to defects in fusion, where layers are not properly bonded. Adjusting the laser energy to the keyhole regime can help mitigate this issue [13]. Additionally, laser manufacturing can also cause cracks and delamination, affecting stress concentration and fatigue resistance [14].…”

Section: Introductionmentioning

confidence: 99%

Combined Use of Acoustic Measurement Techniques with X-ray Imaging for Real-Time Observation of Laser-Based Manufacturing

Samimi,

Saadabadi,

Hosseinlaghab

2024

Metrology

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Ensuring high-quality control in laser additive manufacturing and laser welding relies on the implementation of reliable and cost-effective real-time observation techniques. Real-time monitoring techniques play an important role in understanding critical physical phenomena, namely, melt pool dynamics and defect formation, during the manufacturing of components. This review aims to explore the integration of acoustic measurement techniques with X-ray imaging for studying these physical phenomena in laser manufacturing. A key aspect emphasized in this work is the importance of time synchronization for real-time observation using multiple sensors. X-ray imaging has proven to be a powerful tool for observing the dynamics of the melt pools and the formation of defects in real time. However, X-ray imaging has limitations in terms of accessibility which can be overcome through combination with other more-accessible measurement methods, such as acoustic emission spectroscopy. Furthermore, this combination simplifies the interpretation of acoustic data, which can be complex in its own right. This combined approach, which has evolved in recent years, presents a promising strategy for understanding acoustic emission signals during laser processing. This work provides a comprehensive review of existing research efforts in this area.

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Understanding keyhole induced-porosities in laser powder bed fusion of aluminum and elimination strategy

Cited by 30 publications

References 31 publications

Understanding Melt Pool Behavior of 316L Stainless Steel in Laser Powder Bed Fusion Additive Manufacturing

Understanding Melt Pool Behavior of 316L Stainless Steel in Laser Powder Bed Fusion Additive Manufacturing

Influence of Moisture on the Properties of AlSi10Mg Powder for Laser Powder Bed Fusion

Combined Use of Acoustic Measurement Techniques with X-ray Imaging for Real-Time Observation of Laser-Based Manufacturing

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