Modeling of the polycrystalline cutting of austenitic stainless steel based on dislocation density theory and study of burr formation mechanism

The presence of burrs in mechanical processing can negatively affect surface integrity and dimensional accuracy and even lead to part scrapping. Grain size also has a significant impact on material properties and subsequently generate different processing effects. However, only few studies have explored the effect of grain size on machined surface integrity and burr formation. To fill this gap, this study develops a model based on dislocation density and incorporates this model into ABAQUS using subroutines to investigate polycrystalline cutting modeling and the burr formation mechanism. In addition, the plastic flow and deformation process of grains are observed using a newly developed 2D polycrystalline model, which is later compared with traditional Johnson-Cook constitutive models. The simulated cutting force value, chip morphology, and experimental results are also compared to preliminarily validate the feasibility of the developed model. The experimental results remain consistent across different simulated cutting speeds and depths. The height and width of the exit burr slightly decrease along with increasing cutting speed. Meanwhile, increasing the cutting depth significantly increases the burr width and height. The lateral burrs observed in the experiment can also be reproduced using a 3D polycrystalline model. The lateral burr size increases along with cutting depth and speed. The effect of grain size on cutting force and burr formation is eventually explored, and results show that increasing the grain size reduces the cutting force but increases the burr size. This study provides a new concept for burr control and surface integrity improvement.