Thermal behavior and formation mechanism of a typical micro-scale node-structure during selective laser melting of Ti-ba
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lective laser melting (SLM) technology efficiently solves the current manufacturing challenges of high-performance porous structure components, due to its freeform fabrication principle. As the most basic and crucial structure element, the nodes of porous structure component play an important role in its mechanical property. In this study, finite element method was used to investigate the thermal behavior during SLM processing of micro-scale node-structure. The dynamic size of molten pool was continuously predicted and consequently the typical “necking” effect was found, which was consistent with the experiment results. Besides, the influence of laser scan speed on temperature and temperature gradient of molten pool was also analyzed. The results indicated that the “necking” effect became more conspicuous with the applied scan speed increasing, which significantly deteriorated the mechanical property of porous structure components.
I. INTRODUCTION
With the help of lightweight design, bionic design and topological optimization design, porous structure components have obtained a successful development and started to achieve certain applications in aerospace, automobile, and biomedical field, in view of their superior mechanical properties and special physical properties.1–6 However, suffering from serious limitation of the traditional manufacturing technology, the structure design of porous structure components must be performed in consideration of current manufacturing challenges. Selective laser melting (SLM) technology, as a typical one of laser additive manufacturing technology, due to its freeform fabrication principle which overcomes current manufacturing challenges, has achieved a great attention.7–9 Consequently, SLM can efficiently meet the urgent demanding of highperformance porous structure component. A mass of porous structure components prepared by SLM have been reported. Gu et al.10 successfully prepared “lobster eyes” structure with pores of 0.2 0.2 mm2 by SLM based on the bionic design, aiming at the application of radiation protection. Maskery et al.11 applied SLM technology to produce graded density Al–Si10–Mg lattice structures and meanwhile evaluated the relationship between lattice geometry and mechanical property. This graded lattice structure could absorb more energy with Contributing Editor: Jürgen Eckert a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2017.112
around 7% lower strain before densification, comparing with the uniform lattice structure. Haberland et al.12 investigated the influence of the additive manufacturing (AM) process on structural and functional properties of additively manufactured NiTi. Besides, he showed us the novel application examples of AM-NiTi structures with highly complex geometries. However, during SLM processing of the above functional porous structures, a large number of nodes formed by crossed scanning tracks when a two-dimensional profile for the porous structure are processed, nearby where pores and cracks are prone t
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