Research On Hot Forming Fracture Predicition Of High Strength Steel TRB Based On Ductile Fracture Criterion

Continuous tailor rolling variable-section (Tailor Rolled Blanks, TRB)’s mainfeature is the thickness change along the rolling direction which can optimize thethickness distrubution according to the strength requirements. The high strength steelTRB can be used in the vehicle structural safety parts through hot stamping, the partsmade in this way can not only satisfy the security, but also can reduce the body weight,so as to realize the purpose of energy saving and emission reduction.Fracture is one of the main defects in hot stamping process, the paper’s mainpurpose in to draw up the influence of main factors in hot stamping process, which is ofgreat significance to guide the production practice.This Article has research on different factors’ influence on material movement andthe effect of sheet thickness reduction ratio for asymmetrical u-shaped piece withB1500HS for substrate material in hot stamping process including the transition zonegrandient as well as the radius of mould, friction coefficient, temperature and theclearance between the punch and die by the method of numerical simulation with takingthe variable thickness plate as the even plate.A series of hot tensile experiments are conducted using Gleeble3500to concludethe stress-strain curve of B1500HS under different temperature and strain radio ofdifferent even thickness plate with two strain forms, by using the method ofinterpolation fitting to determine the performance curve of variable thickness plate, atthe same time,combing the Lemaitre ductile fracture criterion and simulating of thesame set with the tests, extracting the corresponding results including the equivalentstrain and stress triaxiality to compute the material parametres so as to construct thefracture prediction criterion.By dicretization the transition zone of TRB, applying different material property todifferent thickness zone so as to approximate the TRB property. On the basis of abovework,applying the fracture predicition criterion to TRB hot tensile, U-shape hotstamping and B-cloumn hot stamping predicition, which is of great significance foractural production.