Hirsch M, Catchpole-Smith S, Patel R, Marrow P, Li Wenqi, Tuck C, Sharples S D, Clare A T
Optics and Photonics Group, University of Nottingham, Nottingham, NG7 2RD, UK.
Advanced Component Engineering Laboratory, University of Nottingham, Nottingham, NG7 2RD, UK.
Proc Math Phys Eng Sci. 2017 Sep;473(2205):20170194. doi: 10.1098/rspa.2017.0194. Epub 2017 Sep 13.
Developments in additive manufacturing technology are serving to expand the potential applications. Critical developments are required in the supporting areas of measurement and in process inspection to achieve this. CM247LC is a nickel superalloy that is of interest for use in aerospace and civil power plants. However, it is difficult to process via selective laser melting (SLM) as it suffers from cracking during rapid cooling and solidification. This limits the viability of CM247LC parts created using SLM. To quantify part integrity, spatially resolved acoustic spectroscopy (SRAS) has been identified as a viable non-destructive evaluation technique. In this study, a combination of optical microscopy and SRAS was used to identify and classify the surface defects present in SLM-produced parts. By analysing the datasets and scan trajectories, it is possible to correlate morphological information with process parameters. Image processing was used to quantify porosity and cracking for bulk density measurement. Analysis of surface acoustic wave data showed that an error in manufacture in the form of an overscan occurred. Comparing areas affected by overscan with a bulk material, a change in defect density from 1.17% in the bulk material to 5.32% in the overscan regions was observed, highlighting the need to reduce overscan areas in manufacture.
增材制造技术的发展正在扩大其潜在应用范围。为实现这一目标，在测量和过程检测等支持领域需要取得关键进展。CM247LC是一种镍基高温合金，在航空航天和民用发电厂中有应用价值。然而，由于其在快速冷却和凝固过程中会出现裂纹，通过选择性激光熔化（SLM）加工很困难。这限制了使用SLM制造CM247LC零件的可行性。为了量化零件完整性，空间分辨声学光谱（SRAS）已被确定为一种可行的无损评估技术。在本研究中，结合光学显微镜和SRAS来识别和分类SLM制造零件中存在的表面缺陷。通过分析数据集和扫描轨迹，可以将形态信息与工艺参数相关联。利用图像处理来量化孔隙率和裂纹，以进行体积密度测量。表面声波数据分析表明，制造过程中出现了过扫描形式的误差。将受过度扫描影响的区域与块状材料进行比较，观察到缺陷密度从块状材料中的1.17%变为过度扫描区域中的5.32%，这突出了在制造过程中减少过度扫描区域的必要性。
