Light weight metal parts produced with additive manufacturing have gained increasing interest from the aerospace industry in recent years. However, light weight parts often require thin walls which can have different material properties compared to thick bulk material. In this work, the fatigue properties of Ti-6Al-4 V produced by electron beam powder bed fusion have been investigated for samples with three different wall thicknesses ranging from 1.3 to 2.7 mm and in three different directions; 0°, 45°, and 90° relative to the build plate. Generally, the 90° specimens show worse fatigue life compared to both 0° and 45°. It was found that the fatigue strength is lower for thin samples compared to thicker samples when the stress is calculated from nominal thickness or calliper measurements. However, since materials produced by electron beam powder bed fusion often have a rough as-built surface, the load bearing area is not easy to determine. In this paper, four different methods for determining the load bearing area are presented. It is shown that if the surface roughness is considered when calculating the stress levels, the influence from specimen thickness decreases or even disappears.

中文翻译：

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增材制造 E-PBF Ti-6Al-4 V 厚度测量方法的疲劳响应依赖性

近年来，通过增材制造生产的轻质金属零件越来越受到航空航天业的关注。然而，轻质零件通常需要薄壁，与厚的散装材料相比，薄壁可能具有不同的材料特性。在这项工作中，研究了电子束粉末床熔融产生的 Ti-6Al-4 V 的疲劳性能，这些样品具有 1.3 至 2.7 mm 的三种不同壁厚和三个不同方向的样品；0°、45° 和 90° 相对于构建板。通常，与 0° 和 45° 相比，90° 试样的疲劳寿命更差。发现当应力由标称厚度或卡尺测量值计算时，薄样品的疲劳强度低于厚样品。然而，由于电子束粉末床熔融生产的材料通常具有粗糙的建成表面，因此不易确定承载面积。在本文中，介绍了确定承重面积的四种不同方法。结果表明，在计算应力水平时考虑表面粗糙度，试样厚度的影响减小甚至消失。