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Influence of Surrounding Powder Bed&Build Platform on Thermal Cooling Characteristics in 3D Printing

Selective laser melting (SLM) leads to high cooling rates and correspondingly high residual stresses, which can distort the printed part on the printing platform and even lead to part cracking and consequent print failure. The temperature profile and cooling rates during the SLM process are influenced by the surrounding powder bed and building platform, which can act as a significant heat sink depending on part design and platform arrangement. The new functionality of the Abaqus additive manufacturing simulation framework allows for separate modelling of solid (laser exposed) material, powder bed (not exposed) and platform (not exposed), as well as evolving heat transfer surfaces for the AM part. In this paper we highlight the influence of the surrounding powder bed and platform on the thermal characteristics of the printed part. We undertake detailed investigations regarding the temperature characteristics with separate meltpool and nodal flux process simulation with regard to mesh size and increment size. We additionally investigate the potential of simplified modelling approaches to reduce the additional computational time by including the surrounding powder bed using equivalent thermal boundary conditions on the printed part. The presented simulation outcomes increase our understanding of the fundamental heat transfer processes during additive manufacturing, and the findings are also considered transferrable to other powder bed printing processes. The temperature predictions are also able to further explain microstructural and material property changes in printed Inconel 718 cylinders at varying build height and with increasing part build diameter.

This paper highlights application of the C-Therm TCi Thermal Conductivity Analyzer.

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