Numerical Analysis of Molten Pool Behavior and Spatter Formation with Evaporation During Selective Laser Melting of 316L
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Selective laser melting (SLM) has become a key research topic in additive manufacturing (AM) technology in the past few years because it allows a high degree of design freedom and the preparation of high-performance metal parts, as stated by Wang et al.[1] During the SLM process, via a layer-by-layer fashion, a high-energy laser beam is used to selectively melt and consolidate a layer of metal
PINGMEI TANG, MUJUN LONG, and DENGFU CHEN are with the College of Materials Science and Engineering, Chongqing University, Chongqing 400044, China. Contact e-mail: [email protected] HAIQIONG XIE, SEN WANG, XUEPING DING, QI ZHANG, HONGLIN MA, JIE YANG, SHUQIAN FAN, and XUANMING DUAN are with the Chongqing Institute of Green and Intelligent Technology, Chinese Academy of Sciences, Chongqing 400714, China and also with the Chongqing Key Laboratory of Additive Manufacturing Technology and System, Chongqing 400714, China. Contact e-mail: [email protected] Manuscript submitted December 5, 2018.
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powders; then, the combination of adjacent layers forms three-dimensional metallic components.[2] Yap et al.[3] show that metallic components produced from SLM have been found in wide applications in biomedical tissue engineering, the aerospace sector and so on. Nevertheless, the actual applications of metallic components produced by SLM require a strict process control to obtain reliable quality. Generally, compared with laser-sintering processes, SLM process requires relatively high-energy density levels and lower scan velocities to successfully melt and fuse the powder metal material. Due to high-energy intensities applied with the high power laser beam, the evaporation of material and resultant spatter, which refers to the ejection of molten materials and powder particles from the molten pool, have been currently recognized common phenomena.[4,5] Many results showed that the evaporation of material and resultant spatter could bring about a series of defects, thus affected process control of SLM. For example, Dai and Gu[6] recognized that the molten material had a tendency to form humps on top surface of molten pool as evaporation occurred in nitrogen-shielding atmosphere.
Liu et al.[7] found that the incomplete melting of the spatter would bring about inclusions and pores in the parts. Anwar et al.[8] reported that the spatter could cause even more heterogeneity in the layer thickness, and thus influence the uniformity of subsequent powder layers. Therefore, how to overcome or minimize spatter in the operating process have been extensively studied. Intensive research demonstrated that energy input was an important factor affecting the amount of spatter, and reducing energy input could decrease spatter to some extent. Gunenthiram et al.[9] indicated that the amount of ejected particles of 316L stainless steel decreased as reducing the input of laser power. Andani et al.[10] characterized the spatter of aluminum alloy under different laser parameters. They showed that decreasing laser power and
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