Research on the plastic fluidity of high-strength steel 22MnB5 based on the thermal-mechanical-fluid multi-filed coupling

Abstract

The effects of technological parameters such as pre-deformation, strain rate, and final forming temperature on the formability of high-strength steel 22MnB5 were studied. Firstly, the finite element model of thermal-mechanical-fluid coupling was established by finite element simulation software ABAQUS. Secondly, the simulation and experiment of the pure hydraulic bulging with the forming temperature are 20, 100, 300, 500, and 700 °C and were carried out, respectively. Finally, by setting the technological parameters such as the cavity pressure loading rate (2, 4, 6, 8, and10 MPa/s) and final forming temperature T (20, 100, 300, 500, and 700 °C), the numerical simulation and the experiment of the coupling of the initial room temperature pre-deformation and high-temperature final forming were studied, and the optimal combination of process parameters was optimized by making the bulging height as the objective function at the end of the forming process. Keeping the cavity pressure loading rate is invariable; the bulging height difference between the two processes is 12.02, 20.43, 26.18, 33.20, and 39.39 mm, respectively, when the temperature is 300 °C. Keeping the final forming temperature is invariable; when the cavity pressure loading rate is 8 MPa/s and the temperature is 300 °C, the difference of the bulging height difference between the hot hydraulic bulging and room temperature hydraulic bulging is maximum, the largest value is 2.17 mm. Taking the bulging height as the criteria of material forming performance, the combination of the final forming temperature of 300 °C and the cavity pressure loading rate of 8 MPa/s is optimum. Finally, the whole coupling process is divided into three stages, and by using the form of structuring sectionalized constitutive equation, the influence law of the dual action of work hardening and softening on the deformation and fluidity of the material in the compound-forming process is analyzed from the perspective of the evolution law of microstructure.