An analytical model for rapid predicting molten pool geometry of selective laser melting (SLM)

Liu, Binqi; Fang, Gang; Lei, Liping

doi:10.1016/j.apm.2020.11.027

Cited by 64 publications

(24 citation statements)

References 31 publications

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“…It can be explained by the presence of lack-of-fusion zones which are observed for the parts produced with lower energy densities, which is likely due to narrower and shallower melt pools. It was reported by Dong et al (2021) and Liu et al (2021) that relatively low energy densities lead to poor fusion quality of laser tracks and massive lack-of-fusion zones were observed. As a result, the porosity seen in the parts manufactured with low energy densities is generated due to the incomplete fusion of the metal powder during laser scanning and the creation of lack of fusion.…”

Section: Resultsmentioning

confidence: 98%

Laser powder bed fusion (LPBF) of NiTi alloy using elemental powders: the influence of remelting on printability and microstructure

Chmielewska

Wysocki

Gadalińska

et al. 2022

RPJ

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Purpose The purpose of this paper is to investigate the effect of remelting each layer on the homogeneity of nickel-titanium (NiTi) parts fabricated from elemental nickel and titanium powders using laser powder bed fusion (LPBF). In addition, the influence of manufacturing parameters and different melting strategies, including multiple cycles of remelting, on printability and macro defects, such as pore and crack formation, have been investigated. Design/methodology/approach An LPBF process was used to manufacture NiTi alloy from elementally blended powders and was evaluated with the use of a remelting scanning strategy to improve the homogeneity of fabricated specimens. Furthermore, both single melt and up to two remeltings were used. Findings The results indicate that remelting can be beneficial for density improvement as well as chemical and phase composition homogenization. Backscattered electron mode in scanning electron microscope showed a reduction in the presence of unmixed Ni and Ti elemental powders in response to increasing the number of remelts. The microhardness values of NiTi parts for the different numbers of melts studied were similar and ranged from 487 to 495 HV. Nevertheless, it was observed that measurement error decreases as the number of remelts increases, suggesting an increase in chemical and phase composition homogeneity. However, X-ray diffraction analysis revealed the presence of multiple phases regardless of the number of melt runs. Originality/value For the first time, to the best of the authors’ knowledge, elementally blended NiTi powders were fabricated via LPBF using remelting scanning strategies.

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Section: Resultsmentioning

confidence: 98%

Laser powder bed fusion (LPBF) of NiTi alloy using elemental powders: the influence of remelting on printability and microstructure

Chmielewska

Wysocki

Gadalińska

et al. 2022

RPJ

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“…The forming characteristics of melt pool morphologies between adjacent scanning tracks and layers and the effect of melt pool morphology on the final forming geometry of SLM object would be covered in future work. Liquid specific heat capacity 𝐶 𝑙 (J/(kgK)) 720 [40] 872 [41] 770 [3] Solid specific heat capacity 𝐶 𝑠 (J/(kgK)) 435 [40] 763 [41] 680 [3] Latent heat of fusion ℎ sl (J/kg) 2.1e 5 3.65e 5 2.7e 5 Thermal conductivity 𝑘(W/(mK)) 24.1 [42] 21 [42] 36 [42] Boiling temperature 𝑇 𝑏 (K) 3111 [40] 3300 [3] 3273 [15] Melting temperature 𝑇 𝑚 (K) 1609 [42] 1928 [30] 1700 [3] Convection coefficient 𝛼 𝑔 (W(m 2 K)) 8 [43] 10 [44] 100 [45] Thermal radiation coefficient 𝜀 0.32 [40] 0.43 [8] 0.35 [45] Density 𝜌(kg/m 3 ) 7451 [39] 4000 [41] 7800 [42] Powder compaction rate 𝜌 𝑝 /𝜌 𝑠 0.6 [11] 0.6 [11] 0.6 [11] Stefan-Boltzmann coefficient 𝜎(W/(m 2 K 4 )) 5.67e -8 5.67e -8 5.67e -8 Appendix B Adopted energy absorptivity under different machines and process conditions for IN718, TC4 and 316L…”

Section: Discussionmentioning

confidence: 99%

“…According to different melting states, the melt pool steady-state temperature is presumed as shown in Formula (15). 𝜆 indicates the ratio of steady-state temperature ( 𝑇 𝑚𝑠 ) to the melting temperature ( 𝑇 𝑚 ), and is adopted according to experimental observations and experience [3,8].…”

Section: Quantitative Calculation Model Of Melt Pool Morphology 221 Critical Melt Pool Geometry Calculationmentioning

confidence: 99%

A Computational Model of Melt Pool Morphology for Selective Laser Melting Process

Qiao

Huang

et al. 2021

Preprint

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Selective laser melting (SLM) is a promising metal additive manufacturing technology, which holds widespread applications in numerous fields. Unfortunately, it is arduous to predict the real SLM part geometry, which impedes its further development. While the morphology of melt pool, influenced and determined by process parameters, poses a crucial influence on the overall part geometry. Nonetheless, the association between process parameters and melt pool morphology is still unclear. Hence it is indispensable to explore relevant solution to address this issue. For this purpose, this paper proposes a new model to directly establish the mathematical relationship between process parameters and melt pool structure for SLM process. In this model, the status of melt pool is first qualitatively analyzed via the defined synthetic process index, and three types of melting states are differentiated including low melting, intermediate melting and high melting, which could cover different melt pool modes. Then, the computational model involving more physical mechanisms integrating mass conversion, heat exchange and temperature field is constructed. Melt pool critical geometries including the height, width, depth and length could be computed through the model. In order to validate the correctness of the proposed model, published experimental observations and existing models are compared. Calculation results from the proposed model show high consistency with the experimental samples and better accuracy than existing empirical models. Its applicability in melt pool classification and prediction is also verified, laying foundation for geometric simulation of SLM object which is successively shaped melt-pool by melt-pool.

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“…Moreover, the variety of assumptions and idealizations that have to be made are aspects taken into account by the researchers (Hodge et al, 2016;Li et al, 2018b;Luo and Zhao, 2017). The revised works in this item discuss the accuracy (comparing model with experiments) and others depict the numerical calculations' computational throughput (Liu et al, 2021). The tridimensional transient thermal behavior of the fabricated parts is commonly obtained by solving the following governing equations of conservation of mass, momentum and energy (Gu et al, 2020;Kan et al, 2021;Marin et al, 2021):…”

Section: Thermo-mechanical Modelsmentioning

confidence: 99%

Selective laser melting: lessons from medical devices industry and other applications

Fé-Perdomo

Ramos‐Grez

Beruvides³

et al. 2021

RPJ

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Purpose The purpose of this paper is to outline some key aspects such as material systems used, phenomenological and statistical process modeling, techniques applied to monitor the process and optimization approaches reported. All these need to be taken into account for the ongoing development of the SLM technique, particularly in health care applications. The outcomes from this review allow not only to summarize the main features of the process but also to collect a considerable amount of investigation effort so far achieved by the researcher community. Design/methodology/approach This paper reviews four significant areas of the selective laser melting (SLM) process of metallic systems within the scope of medical devices as follows: established and novel materials used, process modeling, process tracking and quality evaluation, and finally, the attempts for optimizing some process features such as surface roughness, porosity and mechanical properties. All the consulted literature has been highly detailed and discussed to understand the current and existing research gaps. Findings With this review, there is a prevailing need for further investigation on copper alloys, particularly when conformal cooling, antibacterial and antiviral properties are sought after. Moreover, artificial intelligence techniques for modeling and optimizing the SLM process parameters are still at a poor application level in this field. Furthermore, plenty of research work needs to be done to improve the existent online monitoring techniques. Research limitations/implications This review is limited only to the materials, models, monitoring methods, and optimization approaches reported on the SLM process for metallic systems, particularly those found in the health care arena. Practical implications SLM is a widely used metal additive manufacturing process due to the possibility of elaborating complex and customized tridimensional parts or components. It is corroborated that SLM produces minimal amounts of waste and enables optimal designs that allow considerable environmental advantages and promotes sustainability. Social implications The key perspectives about the applications of novel materials in the field of medicine are proposed. Originality/value The investigations about SLM contain an increasing amount of knowledge, motivated by the growing interest of the scientific community in this relatively young manufacturing process. This study can be seen as a compilation of relevant researches and findings in the field of the metal printing process.

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An analytical model for rapid predicting molten pool geometry of selective laser melting (SLM)

Cited by 64 publications

References 31 publications

Laser powder bed fusion (LPBF) of NiTi alloy using elemental powders: the influence of remelting on printability and microstructure

Laser powder bed fusion (LPBF) of NiTi alloy using elemental powders: the influence of remelting on printability and microstructure

A Computational Model of Melt Pool Morphology for Selective Laser Melting Process

Selective laser melting: lessons from medical devices industry and other applications

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