关键词: 楔横轧, 耦合损伤模型, 芯部损伤, 数值模拟

Abstract: Due to the cumulative central damage behavior in cross wedge rolling, it was prone to form central porosity defects, thus it was of great significance for high-performance manufacturing of cross wedge rolling shaft parts to accurately predict the formation conditions of central damages. The hot tensile tests were conducted under different conditions to obtain the main factors that affected material damages. Subsequently, the coupled damage constitutive models considering temperature, strain rate and stress triaxiality were proposed based on continuous damage mechanics. Furthermore, experiments on cross wedge rolling with different area reduction were conducted to calibrate the material fracture threshold of the damage constitutive model and verify the prediction accuracy of the damage model. The models were used to predict the influence laws of area reduction, spreading angle, and forming angle on central damage, which provided references for parameter selection. The results show that temperature, strain rate and stress triaxiality all significantly affect material damage behavior, and the established coupled damage constitutive models may effectively predict the evolution processes of central damages in cross wedge rolling. The central damages of cross wedge rolling are inversely proportional to the forming angle, and is directly proportional to the spreading angle and area reduction. The degree of influence of each parameters, from small to large, is in order of area reduction, spreading angle, and forming angle.

Key words: cross wedge rolling, coupled damage model, central damage, numerical simulation