Simulation Optimization And Experiment Research On Hot Stamping Of22MnB5High-strength Steel

In order to meet the need of automobile lightweight, the hot stamping technology ofhigh-strength steel has been widely applied. However, influenced by technological monopolyand technical blockade, Chinese research on the main process parameters and their optimizationthat affect sheet metal forming quality is not perfect, which make the technology and equipmentheavily depend on importing. Therefore, in order to promote the development of Chineseautomotive lightweight and realize the localization on hot stamping technology of high-strengthsteel, developing the basic theory and experiment research on hot stamping of high-strength steelis of important theoretical significance and application value.In this paper, making simulation optimization and experiment research on hot stamping of22MnB5high-strength steel and establishing the thermal-mechanical coupling finite elementmodel of22MnB5high-strength steel during hot stamping forming process based onANSYS/LS-DYNA. Based on the established thermal coupling finite element model, makingsingle factor simulation analysis and orthogonal simulation optimization design to research theinitial temperature of sheet, punching speed, BHF, friction coefficient and dwell time, thenachieving the influence rules of various parameters and getting the optimized process parameters,and finally taking an experimental verification. The specific studies are as follows:1. The thermal-mechanical coupling model of22MnB5high strength steel for hot stampingis established by using ANSYS/LS-DYNA; the impact of the main process parameters includingthe initial temperature, punching speed, BHF, friction coefficient and dwell time of hot stampingis researched with the single-factor method. The results show that:(1) With the formingtemperature increasing, the forming sheet will present higher temperature and the maximumtemperature has greater change than the minimum one, while the maximum stress increases firstand then decreases.(2) As the punching speed increases, the maximum temperature of the sheetremains substantially unchanged, while the minimum temperature increases first and thendecreases. The maximum stress decreases first and then increases and it is down to the minimumwhen punching speed is40mm/s.(3) The sheet temperature is not sensitive to the BHF changesin a certain range, the stress is reduced when BHF increases.(4) The temperature reduces and thestress changes opposite when dwell time increases.(5) When friction coefficient increasesgradually, the temperature appears a slight rise, while the stress decreases first and thenincreases.2. Choosing the initial temperature, punching speed, BHF, dwell time and frictioncoefficient as test variables, making use of the L25(56) orthogonal table to conduct the orthogonal simulation optimization design. At the same time, by adopting the range analysis and varianceanalysis to deal with the orthogonal experimental data results, the results show that: the impactof dwell time on the stress is the maximum, punching speed and BHF are smaller, the sheetmetal initial temperature takes the third place, and friction coefficient is the minimum. Theoptimal process parameters combination is the initial temperature of sheet900℃, punchingspeed30mm/s, BHF50KN, dwell time2s and friction coefficient0.2.3. Tracking hardness and microstructure of the selected points on the sheet and completingthe experimental validation of process parameters optimization; the experimental result showsthat hardness of the optimized part increased nearly20%.