In this study, the crack‐growth approach is used to predict the fatigue life of 17‐4 precipitation hardening (PH) stainless steel (SS) fabricated via an additive manufacturing (AM) system in different orientations (ie, vertical and horizontal) before and after heat treatment. To perform fatigue‐life calculations, the effective stress intensity factor as a function of crack‐growth rate was obtained from testing modified compact specimens with different crack orientations in as‐built and heat‐treated conditions. The plasticity‐induced crack closure model, FASTRAN, was used to calculate fatigue lives based on the size of process‐induced defects. Results indicated that in the presence of large voids (ie, lack‐of‐fusion defects), the total fatigue life of AM 17‐4 PH SS in as‐built and heat‐treated conditions is dominated by crack growth. Effect of build orientation on fatigue life of AM 17‐4 PH SS was also captured based on the size of defects projected on a plane perpendicular to the loading direction.

中文翻译：

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增材制造材料的疲劳寿命预测：热处理和成型方向的影响

在这项研究中，采用裂纹扩展方法来预测通过增材制造（AM）系统在不同方向（即垂直和水平）之前制造的17-4沉淀硬化（PH）不锈钢（SS）的疲劳寿命。并经过热处理。为了进行疲劳寿命计算，有效应力强度因子是裂纹扩展速率的函数，是通过在建造和热处理条件下测试具有不同裂纹方向的变形致密试样而获得的。可塑性诱导的裂纹闭合模型FASTRAN用于根据过程引起的缺陷的大小来计算疲劳寿命。结果表明，在存在大空隙（即无熔合缺陷）的情况下，AM 17-4 PH SS在竣工和热处理条件下的总疲劳寿命主要由裂纹扩展决定。