Mechanisms of hot deformation and surface instability in coarse-grained IN625 with data-driven predictive modeling

A study is conducted on the thermal deformation behavior of IN625. Thermal deformation experiments are performed at temperatures ranging from 1000 to 1150 °C and strain rates from 0.01 to 10s−1. Multiscale microstructural characterization is carried out on both the central and surface regions of the specimens under various deformation conditions. The deformation instability manifests primarily as surface crack formation induced by localized deformation. Quantitative relationships among deformation conditions, deformation mechanisms, flow stress, hot workability, and instability behavior are established. In addition, the influence of coarse grain size on the mechanism of surface crack formation is examined. Finally, using the neural network approach, the prediction of flow stress and hot workability from deformation conditions is achieved, and the applicability of the model is comprehensively validated. This research provides a theoretical foundation for optimizing the hot forming processes of nickel-based alloys and other metal materials with coarse grain sizes.