Effect of the track length and track number on the evolution of the molten pool characteristics of SLMed Al alloy: Numerical and experimental study

Liu, Shiwen; Zhu, Junjie; Zhu, Haihong; Yin, Jie; Chen, Changpeng; Zeng, Xiaoyan

doi:10.1016/j.optlastec.2019.105924

Cited by 26 publications

(10 citation statements)

References 24 publications

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“…Previous observations in L-PBF processed Alloy 718 have indicated that the inter-dendritic regions are mainly composed of Laves phase and NbC that are induced by the eutectic reactions. [50][51][52] As suggested in the previous studies, [53] the average cellular spacings were measured to be 490 and 390 nm for C1 and C3 samples without CoAl 2 O 4 , respectively, showing that the cooling rates of the melt pool increased with increasing scan speeds. It is noteworthy that the average cellular spacings were measured to increase to 620 and 430 nm, respectively, for C1 and C3 samples containing CoAl 2 O 4 .…”

Section: Microstructure and Hardnesssupporting

confidence: 77%

Toward the Understanding of CoAl2O4 Additions on the Formation of Microstructure in Alloy 718 Processed by Laser Powder Bed Fusion

Chang

Tiparti

et al. 2022

Metall Mater Trans A

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This investigation rationalizes the impact of oxide particles on the melt pool and subsequent formation of microstructure in superalloy Inconel 718 (Alloy 718) processed by laser powder bed fusion (L-PBF). A mixture of Alloy 718 powder with 0.2 wt pct of CoAl 2 O 4 was processed without scan rotation. It was found that the physical presence of oxides appeared to increase the degree of melt pool penetration by inhibiting the heat transfer. Without favorable thermal conditions to trigger heterogeneous nucleation, a more noticeable tendency to form columnar grains was characterized in samples with CoAl 2 O 4 . It is believed that the presence of oxide particles in the melt pool contributed to decreasing the cooling rates during solidification and retarded the columnar-to-equiaxed transition. A comparatively deeper degree of melt pool penetration also enhanced the relative density of samples with CoAl 2 O 4 . Despite the occurrence of the balling phenomenon, the reduced Marangoni convection also contributed to less micro-humping and better continuity of the melt tracks that decreased the surface roughness by at least 16.7 pct. The addition of CoAl 2 O 4 to the powder feedstock significantly impacted the processing window of L-PBF processed Alloy 718 and may potentially be used as a means to engineer the microstructure.

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Section: Microstructure and Hardnesssupporting

confidence: 77%

Toward the Understanding of CoAl2O4 Additions on the Formation of Microstructure in Alloy 718 Processed by Laser Powder Bed Fusion

Chang

Tiparti

et al. 2022

Metall Mater Trans A

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“…The body heat source, q 1 , is used to define the laser energy absorbed by the powder bed. It is described as (Liu et al , 2018; Liu et al , 2019): where A 1 is the ratio of laser energy absorbed by the powder bed, P is the laser power (W); r 1 is the radius of the heat source q 1 ; and η 1 is the laser penetration depth (μm) of powder which is regarded as one thickness of powder layer (Liu et al , 2018; Yin et al , 2015).…”

Section: Finite Element Modelmentioning

confidence: 99%

“…The body heat source, q 1 , is used to define the laser energy absorbed by the powder bed. It is described as Liu et al, 2019):…”

Section: Combined Heat Source Modelmentioning

confidence: 99%

Distribution and evolution of thermal stress in laser powder bed fusion: conduction mode versus keyhole mode

Chen

Xiao

Xue

et al. 2022

RPJ

Self Cite

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Purpose High temperature gradient induces high residual stress, producing an important effect on the part manufacturing during laser powder bed fusion (LPBF). The purpose of this study is to investigate the effect of the molten pool mode on the thermal stress of Ti-6Al-4V alloy during different deposition processes. Design/methodology/approach A coupled thermal-mechanical finite element model was built. The developed model was validated by comparing the numerical results with the experimental data in the maximum molten pool temperature, the molten pool dimension and the residual stress described in the previous work. Findings For the single-track process, the keyhole mode caused an increase in both the maximum stress and the high-stress area compared with the conduction mode. For the multitrack process, a lower tensile stress around the scanning track and a higher compressive stress below the scanning track were found in the keyhole mode. For the multilayer process, the stress along the scanning direction at the middle of the part changed from tensile stress to compressive stress with the increase in the deposition layer number. As the powder layer number increased, the stress along the scanning direction near the top surface of the part decreased while the stress along the deposition direction obviously increased, indicating that the stress along the deposition direction became the dominant stress. The keyhole mode can reduce the residual stress near the top of the part, and the conduction mode was more likely to produce a low residual stress near the bottom of the part. Originality/value The results provide a systematic understanding of thermal stress during the LPBF process.

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“…Consequently, precise simulation of stress profiles of SLM elements is critical to understand the process for creating highquality components. Several numerical approaches have been established in recent years by various researchers to understand SLM process-induced behaviors, especially residual stresses, such as Bian et al(2019Bian et al( , 2020, Chen et al(2019aChen et al( , 2019b and Liu et al(2020b). To deal with the temperature distribution inside the material during the SLM processing, some early models incorporated finite element analysis (Khan et al, 2018a(Khan et al, , 2018bLi et al, 2017;Li and Xiong, 2019;Majeed et al, 2019).…”

Section: Introductionmentioning

confidence: 99%

Evolution of temperature and residual stress behavior in selective laser melting of 316L stainless steel across a cooling channel

Khan

Waqar

Koç

2022

RPJ

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Purpose The current investigation aims at observing the influence of the cooling channel on the thermal and residual stress behavior of the selective laser melting (SLM)316L uni-layer thermo-mechanical model. Design/methodology/approach On a thermo-mechanical model with a cooling channel, the effect of scanning direction, parallel and perpendicular and scan spacing was simulated. The effect of underlying solid and powder bases was evaluated on residual stress profile and thermal variables at various locations. Findings The high heat dissipation of solid base due to high cooling rates and steep thermal gradients can reciprocate with smaller melt pool temperature and melt pool size. Given the same scan spacing, residual stresses were found lower when laser scanning was perpendicular to the cooling channel. Moreover, large scan spacing was found to increase residual stresses. Originality/value Cooling channels are increasingly being used in additive manufacturing; however, their effect on the residual stress behavior of the SLM component is not extensively studied. This research can serve as a foundation for further inquiries into the impact of base material design such as cooling channels on manufactured components using SLM.

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Effect of the track length and track number on the evolution of the molten pool characteristics of SLMed Al alloy: Numerical and experimental study

Cited by 26 publications

References 24 publications

Toward the Understanding of CoAl2O4 Additions on the Formation of Microstructure in Alloy 718 Processed by Laser Powder Bed Fusion

Toward the Understanding of CoAl2O4 Additions on the Formation of Microstructure in Alloy 718 Processed by Laser Powder Bed Fusion

Distribution and evolution of thermal stress in laser powder bed fusion: conduction mode versus keyhole mode

Evolution of temperature and residual stress behavior in selective laser melting of 316L stainless steel across a cooling channel

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