Research on the thermomechanical field modeling and microstructural evolution during cutting AISI9310

This study focuses on the thermomechanical field modeling and microstructural evolution during cutting AISI9310, which is a high-performance steel widely used in critical gear and shaft applications. At first, the analytical models for predicting mechanical and thermal loads are developed. The mechanical model with a prediction error of 15% for cutting force can be used to calculate the distribution of all the stress components; the thermal model has a prediction error of 20% for temperature. By making use of the mechanical and thermal models, the thermomechanical field beneath the machined surface during the quasi-orthogonal turning of AISI9310 is calculated. Then EBSD and TEM examinations are conducted on the samples taken from the 0 to 40 (Formula presented.) depth range beneath the machined surface for the characterization of the microstructural evolution. EBSD examinations show that high-density low-angle grain boundaries exist within the 20 µm-depth range, and TEM examinations indicate that high-density dislocations accumulate within the grains as well as at the grain boundaries of this region. Further analytical calculation based on the mechanical and thermal loading models shows that the area within the 20 µm-depth range is characterized by a high level of normal stresses and shear stress, which is higher than the macroscopic yield point as well as the Critical Resolved Shear Stress (CRSS), together with a temperature distribution varying from 70 to 350 °C. Such a thermomechanical field is apt to promote the dislocation multiplication and movement.