Study On Hot Forming Properties Of Ultra High Strength Boron Steel Based On Multi-objective Parameters Optimization

Hot stamping technology of ultra high strength steel is the most popularlightweight of automobile technology. However, the technology is complexity than theconventional technology of cold-forming. Considering the technology involves a phasechange and heat transfer, needing more boundary conditions into consideration to avoidcracking and wrinkling. So the paper takes BR1500HS boron steel as the researchobject, through theoretical analysis, the thermal simulation, and thermo-mechanicalcouple numerical simulation and experimental to study the impact of process parameterson the hot forming performance. The main works are as follows:①In order to simulate the hot stamping process of BR1500HS at elevatedtemperature, tensile tests are carried out through Gleeble1500system. Obtaining themechanical properties at different heating temperature, holding time and strain rate.Getting heat flow stress-strain curves of BR1500HS boron steel and the Arrheniusconstitutive material model is established. Providing the basis to numerical simulationof hot stamping of ultra high-strength boron steel BR1500HS.②Analysis mechanisms of cracking, wrinkling defect of ultra high strength boronsteel BR1500HS. And using univariate analysis to study the impact of initialtemperature, blank holder force, friction coefficient, pressure-holding time on the hotforming performance.③After analyzing the impact of different process parameters on the hot formingperformance. Using orthogonal experiment and response surface methodology thefunction models between process parameters and the performance (the maximumthickness, the minimum thickness and the uniform deformation degree) wereestablished.④Based on Matlab genetic algorithm, it gets the optimization model aboutdeformation uniformity as evaluation, the max and min thickness as constraint, throughcontinuous iterative analysis the approximate optimum combination of parameters isobtained. According to the optimal parameters, the numerical simulation andexperimental test of BR1500HS was taken. The numerical simulation analysis andproduced results verify the accuracy of the analysis of this study.The above research study provide the theoretical basis of the hot formingperformance of high strength boron steel and hot stamping process analysis, which has a high practical engineering significance.