Buchenau Theresa, Mertens Tobias, Lohner Hubertus, Bruening Hauke, Amkreutz Marc
Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM, 28359 Bremen, Germany.
Airbus Operations, 28199 Bremen, Germany.
Materials (Basel). 2023 Jul 4;16(13):4815. doi: 10.3390/ma16134815.
Additive manufacturing technologies enable lightweight, functionally integrated designs and development of biomimetic structures. They contribute to the reduction in material waste and decrease in overall process duration. A major challenge for the qualification for aerospace applications is the surface quality. Considering Ti-64 laser powder bed fusion (LPBF) parts, particle agglomerations and resulting re-entrant features are characteristic of the upper surface layer. Wet-chemical post-processing of the components ensures reproducible surface quality for improved fatigue behaviour and application of functional coatings. The 3D SurFin and chemical milling treatments result in smoother surface finishes with characteristic properties. In order to characterise these surfaces, three methods for surface texture measurement (contact and non-contact) were applied, namely confocal microscopy, fringe projection and stylus profilometry. The aim of this work was to show their suitability for measurement of laser powder bed fusion as-built and post-processed surfaces and compare results across the evaluated surface conditions. A user-oriented rating of the methods, summarising advantages and disadvantages of the used instruments specifically and the methods in general, is provided. Confocal microscopy reaches the highest resolution amongst the methods, but measurements take a long time. The raw data exhibit large measurement artefacts for as-built and chemically milled conditions, requiring proper data post-processing. The stylus method can only capture 2D profiles and the measurement was restricted by particle agglomerations and craters. However, the method (process and instrument) is entirely standardised and handheld devices are inexpensive, making it accessible for a large group of users. The fringe projection method was the quickest and easiest regarding measurement and data post-processing. Due to large areal coverage, reproduction of location when performing repeat measurements is possible. The spatial resolution is lower than for confocal microscopy but is still considered sufficiently high to characterise the investigated surface conditions.
增材制造技术能够实现轻量化、功能集成化设计以及仿生结构的开发。它们有助于减少材料浪费并缩短整个工艺周期。航空航天应用认证面临的一个主要挑战是表面质量。考虑到Ti-64激光粉末床熔融（LPBF）零件，颗粒团聚以及由此产生的凹坑特征是上表面层的特点。对部件进行湿化学后处理可确保可重复的表面质量，以改善疲劳性能并应用功能涂层。3D表面精加工和化学铣削处理可获得具有特征性质的更光滑表面光洁度。为了表征这些表面，应用了三种表面纹理测量方法（接触式和非接触式），即共聚焦显微镜、条纹投影和触针轮廓仪。这项工作的目的是展示它们对激光粉末床熔融成型及后处理表面测量的适用性，并比较不同评估表面条件下的结果。提供了一种面向用户的方法评级，具体总结了所用仪器以及一般方法的优缺点。共聚焦显微镜在这些方法中分辨率最高，但测量时间较长。对于成型和化学铣削条件下的原始数据，存在大量测量伪像，需要进行适当的数据后处理。触针方法只能捕获二维轮廓，并且测量受到颗粒团聚和凹坑的限制。然而，该方法（工艺和仪器）完全标准化，手持设备价格低廉，使得大量用户都可以使用。条纹投影方法在测量和数据后处理方面是最快且最简单的。由于大面积覆盖，重复测量时能够重现位置。其空间分辨率低于共聚焦显微镜，但仍被认为足够高，能够表征所研究的表面条件。
