This work represents the first investigation into the influence of residual stress (RS) from powder-based metal additive manufacturing (AM) on the post-process machining-induced stress and distortion for thin-walled components. Machined part distortion and surface residual stress pose major challenges in several industries, including for aerospace applications involving monolithic structures. However, the influence of initial RS in the bulk material on high-speed machining-induced stress and distortion is still not well understood. This is particularly true for more recent hybrid (additive and subtractive) manufactured components in which significant tensile and compressive RS develops from the rapid thermal cycles during the AM build. It is hypothesized in this work that, even for a simple thin-walled structure, the initial RS in the AM bulk material significantly influences the RS and distortion induced by high-speed machining. It is further hypothesized that the degree of influence of the initial RS on machining-induced RS and distortion varies significantly according to the specific tool path, even for the same net material removal. To test these hypotheses, a numerical modeling approach is presented considering a thin-walled directed energy deposition (DED) structure subjected to high-speed end-milling. A compatible RS field for the DED build is established using an iterative reconstruction algorithm based on limited neutron diffraction measurements, and the full reconstructed RS field is then imposed as an initial state in the end-milling simulation that follows. To assess the influence of the initial DED RS on the machining-induced stress and distortion, as well as to examine how this influence varies with machining strategy, two different tool paths are considered for the same net material removal, both with and without considering RS inherent to the DED build. The findings reveal significant influence of the DED RS on the high-speed machining-induced distortion and RS, and further, this influence is seen to vary greatly with the machining strategy. Normalized root-mean-square differences (NRMSD) of up to 25$\%$ and 29$\%$, respectively, are observed in the machining-induced RS for the two different tool paths when DED inherent RS is considered. Likewise, maximum NRMSD of up to 44$\%$ and 40$\%$ are revealed in the post-machining distortion for the two respective machining strategies when DED RS is included. In addition, variations observed in the stress triaxiality computed during machining suggests that inclusion of the DED RS influences the localized response of the material near the tool-workpiece interface. The technical approach demonstrated can be extended beyond hybrid manufacturing to generate important scientific insights regarding distortion and machining-induced stress for conventionally manufactured monolithic components in the aerospace and other performance-critical industries.

这项工作代表了首次研究粉末基金属增材制造 (AM) 的残余应力 (RS) 对薄壁部件的后处理加工引起的应力和变形的影响。机加工零件变形和表面残余应力对多个行业构成重大挑战，包括涉及整体结构的航空航天应用。然而，块状材料中初始 RS 对高速加工引起的应力和变形的影响仍不清楚。对于较新的混合（增材和减材）制造组件而言尤其如此，其中显着的拉伸和压缩 RS 由增材制造过程中的快速热循环产生。在这项工作中假设，即使对于简单的薄壁结构，AM 块状材料中的初始 RS 显着影响高速加工引起的 RS 和变形。进一步假设初始 RS 对加工引起的 RS 和变形的影响程度根据特定的刀具路径而显着变化，即使对于相同的净材料去除也是如此。为了检验这些假设，提出了一种数值建模方法，该方法考虑了经受高速端铣削的薄壁定向能量沉积 (DED) 结构。使用基于有限的中子衍射测量值的迭代重建算法，为DED构建建立了一个兼容的RS场，然后在随后的立铣模拟中将完全重建的RS场作为初始状态。为了评估初始 DED RS 对加工引起的应力和变形的影响，以及检查这种影响如何随加工策略而变化，对于相同的净材料去除，考虑了两种不同的刀具路径，无论是否考虑 RS DED 构建所固有的。研究结果揭示了 DED RS 对高速加工引起的变形和 RS 的显着影响，此外，这种影响被认为随着加工策略的不同而有很大差异。归一化均方根差 (NRMSD) 高达 25 研究结果揭示了 DED RS 对高速加工引起的变形和 RS 的显着影响，此外，这种影响被认为随着加工策略的不同而有很大差异。归一化均方根差 (NRMSD) 高达 25 研究结果揭示了 DED RS 对高速加工引起的变形和 RS 的显着影响，此外，这种影响被认为随着加工策略的不同而有很大差异。归一化均方根差 (NRMSD) 高达 25$\%$ 和 29$\%$当考虑 DED 固有 RS 时，分别在两个不同刀具路径的加工诱导 RS 中观察到。同样，最大NRMSD高达44$\%$ 和 40$\%$当包含 DED RS 时，两种加工策略的加工后失真显示出来。此外，在加工过程中观察到的应力三轴性变化表明，包含 DED RS 会影响工具 - 工件界面附近材料的局部响应。所展示的技术方法可以扩展到混合制造之外，以产生关于航空航天和其他性能关键行业中传统制造的整体部件的变形和加工引起的应力的重要科学见解。