Today, wire arc additive manufacturing (WAAM) can be used to fabricate critical structural steel components. The process allows to fabricate sophisticated shapes, thereby achieving very high levels of material capacity utilization. Key welding parameters inevitably influence the mechanical resistance of components made by WAAM, submitted to static or cyclic loading. In this research, the fatigue behaviour of wire arc additively manufactured carbon steel elements is investigated. Firstly, samples are manufactured by cold metal transfer (CMT) welding process using carbon steel 3Dprint AM 35 (S355) grade and following a welding procedure optimised to limit the welding-induced imperfections. A series of microstructural investigations and mechanical experiments are carried out on milled samples including: (i) hardness tests, (ii) static tensile tests, and (iii) cyclic fatigue tests. Both transverse and longitudinal directions are tested. The obtained fatigue test results are then compared against existing research on equivalent details. A database containing all similar test results and own experimental results is then used to calculate the fatigue detail categories, and to assess the applicability of the current Eurocode and IIW provisions for fatigue. The reliability levels of the proposed fatigue classes are then validated through the use of Weibull models, commonly used in survival analysis.

中文翻译：

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由非合金 S355 钢制成的线弧增材制造部件的疲劳

如今，电弧增材制造 (WAAM) 可用于制造关键的结构钢部件。该工艺可以制造复杂的形状，从而实现非常高水平的材料产能利用率。关键焊接参数不可避免地会影响 WAAM 制造的部件在承受静态或循环载荷时的机械阻力。在本研究中，研究了电弧增材制造碳钢元件的疲劳行为。首先，使用碳钢 3Dprint AM 35 (S355) 等级通过冷金属传递 (CMT) 焊接工艺制造样品，并遵循优化的焊接程序以限制焊接引起的缺陷。对铣削样品进行了一系列微观结构研究和机械实验，包括：(i) 硬度测试、(ii) 静态拉伸测试和 (iii) 循环疲劳测试。横向和纵向均进行测试。然后将获得的疲劳测试结果与等效细节的现有研究进行比较。然后使用包含所有类似测试结果和自己的实验结果的数据库来计算疲劳详细类别，并评估当前欧洲规范和 IIW 疲劳规定的适用性。然后通过使用常用于生存分析的威布尔模型来验证所提出的疲劳等级的可靠性水平。