Simulation Study Of The Formability Of A High Strength Steel For Automobile

Need of the steel for automobiles increases with the rapid development of automobile industry.In order to meet the demand of lightweight of automobile and energy conservation as well asemission reduction, steel with higher strength and better performance are developed by manysteel companies. For the newly developed kind of steel, it is highly important to give a researchto its keyformabilityfor its use.This paper is based on a new kind of low alloy-high strength steel for automobile beam.Firstly the mechanical properties and stress strain curves are attained with tension experimentsunder quasi-static condition and the strain rate of10-4、10-3、10-2respectively. The experimentresults show that the yield strength of this kind of steel is790MPa and its tensile strength, elasticmodulus and elongation are969MPa,227Gpa and20.5%respectively under quasi-staticcondition. Moreover the strength becomes higher with increase of the strain rate.Deformations involved in this study are stamping and rolling forming. Finite element method isused to simulate the deformation process. During the simulation, finite element models areestablished based on the researches existed and the characteristic of each deformation processwith ANSYS.The simulation results indicate that a negative springback occurred during stamping and theside wall becomes circle under the force of springback. Thickness decrease exists and theposition where worst decrease occurrs is located at the upper area of side wall also the decreaseget worse with a increase of stamping speed. To control the springback, two method of anglecompensation and die gap enlargement are taken. The simulation result shows that they caneffectivelydiminish springback.Based on simulation results of roll-forming, the springback in this process is not notable butthe longitudinal bow is quite remarkable. The middle part of the formed beam is8.27mm higherthan the edge part, meanwhile, a thickness decrease occurs at round corner of the beam. Thereaction force becomes larger with an increase of rolling speed.