A phase-field study of neck growth in electron beam powder bed fusion (EB-PBF) process of Ti6Al4V powders under different processing conditions

Rizza, Giovanni; Galati, Manuela; Iuliano, Luca

doi:10.1007/s00170-022-10204-4

Cited by 12 publications

(1 citation statement)

References 88 publications

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“…Experimental comparisons indicate that the phase-field model incorporating temperature field evolution accurately predicts the distribution of temperature fields and variations in microstructural morphology during selective laser sintering. Rizza et al [90] simulated the morphological changes in electron beam-melted Ti6Al4V powder under different temperature histories. They found that both temperature history and powder geometry influence the sintering rate and neck size.…”

Section: Phase-field Sintering Model With Temperature Fieldmentioning

confidence: 99%

Phase-Field Simulation of Sintering Process: A Review

Xue,

2024

CMES

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Sintering, a well-established technique in powder metallurgy, plays a critical role in the processing of high melting point materials. A comprehensive understanding of structural changes during the sintering process is essential for effective product assessment. The phase-field method stands out for its unique ability to simulate these structural transformations. Despite its widespread application, there is a notable absence of literature reviews focused on its usage in sintering simulations. Therefore, this paper addresses this gap by reviewing the latest advancements in phase-field sintering models, covering approaches based on energy, grand potential, and entropy increase. The characteristics of various models are extensively discussed, with a specific emphasis on energy-based models incorporating considerations such as interface energy anisotropy, tensor-form diffusion mechanisms, and various forms of rigid particle motion during sintering. Furthermore, the paper offers a concise summary of phase-field sintering models that integrate with other physical fields, including stress/strain fields, viscous flow, temperature field, and external electric fields. In conclusion, the paper provides a succinct overview of the entire content and delineates potential avenues for future research.

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Section: Phase-field Sintering Model With Temperature Fieldmentioning

confidence: 99%

Phase-Field Simulation of Sintering Process: A Review

Xue,

2024

CMES

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A new approach of preheating and powder sintering in electron beam powder bed fusion

Böhm,

Breuning,

Markl

et al. 2024

Int J Adv Manuf Technol

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Preheating is an essential process step in electron beam powder bed fusion. It has the purpose of establishing a sintered powder bed and maintaining an elevated temperature. The sintered powder bed reduces the risk of smoke and in combination with the elevated temperature improves the processability. Today, the line-ordering preheating scheme is widely used. This scheme does not take the previously built layers into account and results in an inhomogeneous elevated temperature and consequently in a variety of sinter degrees, which is disadvantageous for the process. The main challenge is now to modify this scheme to establish a homogeneous temperature distribution. This study addresses this challenge and analyses as well as optimises this scheme. A GPU-parallelised thermal model reveals a heterogeneous temperature distribution during preheating because of varying thermal conditions within a build job. In addition, a work-of-sintering model predicts that the sinter degree of the current powder layer on top of previously consolidated material is smaller than on top of the surrounding powder bed. This work aims to invert this trend to improve powder re-usage and material consolidation. Consequently, this work proposes an extension of the current scheme, compensating for the specific energy loss with local adjustments to the energy input. This adaption results in a uniform temperature distribution and advantageous sintering. Applying the proposed numerical model proves to be an effective method to analyse the evolving process conditions and tailor the local energy input, thereby improving the efficiency of the preheating step.

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Additive Manufacturing of Locally Weakened Parts to Obtain a Designed Fracture

Galati

Defanti

2023

Met. Mater. Int.

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Today, the additive manufacturing (AM) approach has led to profound changes in part and process design, enabling previously impossible material properties. With the freedom to create the material as components are built layer by layer, AM has permitted precise spatial control of the material properties in manufactured parts. In this work, an original approach is proposed to locally control component and process design and create intentionally weakened regions with designed fracture, which paves the way to tuneable mechanical properties. Tensile tests of specimens with embedded weakened area of various geometries are used to verify the feasibility of a-priori-designed fracture modes and to characterise the variation in material behaviour. The results show that an ad hoc design of the artificially weakened areas is effective for predictable breakage, with load and strain being the precursor for active control of the mechanical behaviour. The attainability of a quantitative relationship between the defect and the mechanical response is exemplified by the fact that, e.g. for a flat geometry, the maximum stress and strain are reduced by half when the thickness of the weak region is doubled. Graphical abstract

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A phase-field study of neck growth in electron beam powder bed fusion (EB-PBF) process of Ti6Al4V powders under different processing conditions

Cited by 12 publications

References 88 publications

Phase-Field Simulation of Sintering Process: A Review

Phase-Field Simulation of Sintering Process: A Review

A new approach of preheating and powder sintering in electron beam powder bed fusion

Additive Manufacturing of Locally Weakened Parts to Obtain a Designed Fracture

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