Three-dimensional finite element model of high strength 21-6-9 stainless steel tube in rotary draw bending and its application

Establishing and developing a finite element (FE) model is the key to the effective research of the complex bending process of a high strength 21-6-9 (0Cr21Ni6Mn9N) stainless steel tube. According to the characteristics of the rotary draw bending process of a high strength stainless steel tube, a three-dimensional (3D) elastic-plastic FE model of the whole rotary draw bending including bending tube, retracting mandrel and unloading is built under ABAQUS/explicit and ABAQUS/standard environment. The key technologies for establishment of the model are described in detail. Then, the reliability of the model is validated by experiment. Furthermore, numerical simulation and analysis of the high strength 21-6-9 stainless steel tube in the whole rotary draw bending process have been carried out by using the model. The results for the distributions and variations of the tangential stress and strain, wall thickness, cross-section deformation, springback angle and springback radius are obtained. The achievements of the study are helpful to develop the bending technique and provide a guideline in rotary draw bending process for the high strength 21-6-9 stainless steel tube.