The residual stress generated in the machining process has a passive influence on the machining accuracy of a thin-walled workpiece. Annealing treatment can release the residual stress induced in the machining process and suppress the machining distortion. However, there is no unified standard for whether annealing treatment is arranged after machining. In this paper, an analytical model for predicting the distortion caused by residual stress of thin-walled superalloy GH4169 is established. Then, the finite element method is applied to analyze the prediction results of the proposed model. It is found that the residual stress generated in the manufacturing process chain can cause large distortion for the thin-walled workpiece. Finally, combined with the law and principle of workpiece distortion, the annealing process planning of multiple manufacturing sequences of thin-walled superalloy GH4169 is formulated to suppress the machining distortion. For the machining process on one side of the workpiece, it is necessary to release residual stress. This is not necessary for the double-sided machining process. Research results can be used to optimize the manufacturing sequence of thin-walled components.

Engineering components are usually manufactured with sequential production processes. Work hardening due to previous production processes affects the machinability of the workpiece in subsequent operations. In this research, the surface work hardening of a workpiece manufactured by two sequential processes with heat treatment/milling (HT + M) and milling/heat treatment (M + HT) of superalloy GH4169 was investigated. First, the surface microstructure characteristics, including plastic deformation and grain size of the machined workpiece surface processed by the two sequential processes, were quantitatively presented. Then, the microhardness on the machined workpiece surface and its cross-section was measured and analyzed. Finally, a surface microhardness calculation model considering twin boundary deformation was proposed. Here, we also present the microstructure evolution principle of the machined workpiece surface by the two sequential processes. It was found that the degree of work hardening of HT + M machining was 179%, whereas that of M + HT was only 101%. The research results can be applied to the optimized selection of process sequence for manufacturing superalloy GH4169.