A Study of Keyhole Porosity in Selective Laser Melting: Single-Track Scanning With Micro-CT Analysis
A Study of Keyhole Porosity in Selective Laser Melting: Single-Track Scanning With Micro-CT Analysis
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DOI：
10.1115/1.4043622
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发表时间：
2019-07
期刊：
影响因子：
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通讯作者：
Subin Shrestha;T. Starr;K. Chou
中科院分区：
文献类型：
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作者：
Subin Shrestha;T. Starr;K. Chou
气孔率是选择性激光熔化(SLM)的固有属性，它会严重降低零件的质量和性能。本研究试图了解和表征SLM在单道扫描过程中形成的小孔。首先，通过改变激光功率和扫描速度，使用不同的线能量密度(LED)水平，从0.1J/mm到0.98J/mm，产生24个单轨。然后用微型计算机断层扫描测量锁孔的孔并分析孔的特征。结果表明，除某些模式外，小孔孔洞的严重程度随着发光二极管的增加而增加，这是一个总体趋势，表明这些参数对小孔孔洞的严重程度有重要的个体贡献。接下来，通过在另一组实验中保持LED恒定，测试了功率和速度的不同组合，以调查个体效应。结果表明，激光功率对孔数、孔容和孔深的影响均大于扫描速度。对于同一个LED，随着激光功率的增加，其孔数和体积都会增加，达到一定的临界值后，如果进一步增加功率，孔数和体积都会减少。对于0.32J/mm、0.4J/mm和0.48J/mm的LED，扭转趋势的临界激光功率分别约为132W、140W和144W。
Porosity is an inherent attribute in selective laser melting (SLM) and profoundly degrades the build part quality and its performance. This study attempts to understand and characterize the keyhole pores formed during single-track scanning in SLM. First, 24 single tracks were generated using different line energy density (LED) levels, ranging from 0.1 J/mm to 0.98 J/mm, by varying the laser power and the scanning speed. The samples were then scanned by micro-computed tomography to measure keyhole pores and analyze the pore characteristics. The results show a general trend that the severity of the keyhole porosity increases with the increase of the LED with exceptions of certain patterns, implying important individual contributions from the parameters. Next, by keeping the LED constant in another set of experiments, different combinations of the power and the speed were tested to investigate the individual effect. Based on the results obtained, the laser power appears to have a greater effect than the scanning speed on both the pore number and the pore volume as well as the pore depth. For the same LED, the pore number and volume increase with increasing laser power until a certain critical level, beyond which, both the pore number and volume will decrease, if the power is further increased. For the LED of 0.32 J/mm, 0.4 J/mm, and 0.48 J/mm, the critical laser power that reverses the trend is about 132 W, 140 W, and 144 W, respectively.