Solidification and Microstructural Control in Selective Electron Beam Melting of Co-29Cr-10Ni-7W Alloy

Abstract:

Electron beam melting (EBM) has been among the most widely applied additive manufacturing techniques providing a high production rate, low residual stress and good mechanical properties of as-fabricated parts. In order for a wider industrial application of EBM, knowledge on alloy suitability for the process is important. In this work, EBM of Co-29Cr-10Ni-7W alloy is studied. During EBM, the alloy solidifies in a typical columnar-dendritic manner with multiple carbide phases formed in interdendritic regions and grain boundaries. Under the commonly used EBM conditions, cracks are readily observed in the EBM-fabricated state. In the present work, the forms of cracking are described and microstructure analysis has been conducted in order to suggest how cracks propagate during EBM. We will also discuss the possibility of controlling EBM operation to alter grain growth orientations and thus to reduce hot cracking. Keywords: melt pools; columnar dendritic growth; hot tearing; liquation cracking

• Periodical: Materials Science Forum (Volume 941)
• Pages: 902-907
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.941.902
• Online since: December 2018
• Authors: Minh A.L. Phan*, Darren Fraser, Zhanwen Chen, Stefan Gulizia
• Keywords: Columnar Dendritic Growth, Hot Tearing, Liquation Cracking, Melt Pools

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