Engineering topics
Vrancken, Bey
Publications and source records attributed to Vrancken, Bey.
Toward multiscale simulations of tailored microstructure formation in metal additive manufacturing
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Residual stress analysis of in situ surface layer heating effects on laser powder bed fusion of 316L stainless steel
Not Available
Microcrack mitigation during laser scanning of tungsten via preheating and alloying strategies
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Influence of Process Parameters and Alloy Composition on Crack Mitigation in Selective Laser Melting
Microcracking and residual stresses are key limitations of laser powder bed fusion (LPBF), an additive manufacturing (AM) technique that uses a high power laser to consolidate successive layers of metal powder. For tungsten, these microcracks find their origin in the combination of a ductile-to-brittle transition (DBT) between 200°C and 400°C and high residual stresses. This work utilized in situ high speed video to capture the cracking mechanisms, and combined the experimental results with thermomechanical modeling to unveil correlations between crack network morphology and process parameter-related variables, such as the local temperature and residual stress distributions. Consequently, preheating and alloying with rare earth oxides were adopted as possible crack mitigation strategies, the efficacy of which was tested against the initial fundamental baseline results. Preheating temperatures above 500°C eliminated all cracking, though this threshold is expected to be higher when tungsten powder (higher oxygen content) is introduced. Alloying can serve as an active oxygen getter in the system, but the rare earth oxides in this work were too large to have significant contributions to crack-mitigation.