Work

Thermo-mechanically driven dynamic recovery and residual stress relaxation in high-efficiency deep grinding of single-crystal superalloys

Year: 2026

Type: article

Abstract: High-efficiency deep grinding (HEDG) is an important process for machining single-crystal superalloy turbine blades, whereas the severe thermo-mechanical coupling and ultrahigh strain rates involved make the evolution of subsurface residual stress difficult to predict accurately. This study develops a physics-based predictive framework linking macroscopic HEDG kinematics with crystallographic material response. A kinematics-based grinding force model and an explicit finite-difference transient thermal model are integrated with an enhanced crystal viscoplastic constitutive framework incorporating strain-rate sensitivity and crystallographic anisotropy. The resulting framework predicts a non-monotonic evolution of grinding-induced residual stress governed by the competition between strain hardening and thermal softening. High-frequency measurements of grinding force and temperature, together with X-ray diffraction (XRD) and electron backscatter diffraction (EBSD), are employed to validate the predicted stress evolution and characterize the associated microstructural mechanisms. The experimentally measured residual stresses remain below 100 MPa over the investigated conditions and are primarily associated with localized dynamic recovery and dislocation rearrangement, which reduce local lattice distortion while largely preserving the crystallographic continuity of the single-crystal matrix. Microstructural features indicative of recrystallization become more pronounced only under more severe thermo-mechanical conditions, suggesting an additional stress-relaxation pathway accompanied by partial degradation of the original single-crystal structure. The proposed elastoplastic stress-relaxation algorithm agrees well with the XRD measurements, with most relative prediction errors falling within 2–7%. An optimized grinding-speed range of 50–110 m/s at a depth of cut of 0.3 mm is identified, providing a mechanistic basis for residual stress control in HEDG of single-crystal superalloys.

Source: Journal of Manufacturing Processes

DOI: 10.1016/j.jmapro.2026.09.069