As the fatigue strength of materials manufactured via lase-based powder bed fusion (PBF-LB) is highly influenced by process-induced defects and the “as-built” surface, in this work fatigue tests at specimens made of AlSi10Mg with “as-built” and polished surface condition were conducted. In this context also the defect tolerance of the material, and hence its ability to counteract process-induced notch effects, was analyzed. For this, specimens in a not heat-treated and an artificially aged (T6) condition were tested. For the not heat-treated specimens, a high reduction of the fatigue strength due to the “as-built” surface is observed, while the heat-treated specimens exhibit no influence of the surface condition. Using the √area approach, it is demonstrated that the smaller fatigue strength due to “as-built” surface observed for the not heat-treated condition results from process-related residual tensile stresses, which are removed by T6 heat treatment and polishing, respectively. Moreover, the results show that the “as-built” surface leads to similar stress concentrations than defects in the specimen volume, and thus, polishing had no influence on the fatigue performance after heat treatment. In addition to these findings, an increased fatigue strength after T6 heat treatment was observed, which is caused by an increased defect tolerance.

中文翻译：

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竣工表面和 T6 热处理对增材制造 AlSi10Mg 疲劳行为的影响


由于通过激光粉末床熔合 (PBF-LB) 制造的材料的疲劳强度很大程度上受到工艺引起的缺陷和“竣工”表面的影响，因此在本次工作疲劳测试中，对由具有“竣工”状态的 AlSi10Mg 制成的样本进行了疲劳测试。进行了“建造”和抛光表面状况。在这种情况下，还分析了材料的缺陷容限，以及其抵消工艺引起的缺口效应的能力。为此，对未经热处理和人工时效（T6）条件下的样本进行了测试。对于未经热处理的样品，观察到由于“竣工”表面而导致疲劳强度大幅降低，而经过热处理的样品则没有表现出表面状况的影响。使用√面积方法，证明了在未热处理条件下观察到的“竣工”表面导致的较小疲劳强度是由与工艺相关的残余拉应力产生的，这些残余拉应力分别通过T6热处理和抛光消除。此外，结果表明，“竣工”表面导致的应力集中与试样体积中的缺陷相似，因此抛光对热处理后的疲劳性能没有影响。除了这些发现之外，还观察到 T6 热处理后疲劳强度增加，这是由于缺陷容限增加所致。