Modelo numérico multiescala para previsão da curva tensão-deformação de aços dual phase pelo método tensão RVE ; Numerical model for predicting the flow behavior of dual phase steel using RVE method

Dual phase steel has stood out in the Advanced High Strength Steels class, being considered as a viable alternative for reducing the emission of gases emitted by mobility vehicles, mainly automotive vehicles powered by combustion. DP steel is considered to be a microcomposite with a biphasic microstructure composed of islands of hard and resistant martensite dispersed in the ductile and soft ferritic matrix, which provides mechanical properties demanded by the mobility industry with a good cost-benefit ratios. Some of the benefits provided by the material, related to vehicles, is the possibility of designing them to increase the safety of passengers, reduce structural weight and, consequently, decrease energy consumption. Given the importance of DP steels, a multiscale numerical model was developed to determine the stress-strain behavior for different DP steel microstructures obtained through the application of different intercritical thermal cycles. A computer program was developed in FORTRAN language for reading digital image processing and identifying phases in the domain of the finite element mesh, which is based on the Real Representative Volume Element generated from information from the Backscattered Electron Diffraction technique. The constitutive equation of applied plasticity is based on Taylor's displacement theory, making it possible to perform the simulation of uniaxial traction through the Finite Element Method on a numerical platform of ABAQUS CAE commercial code. The Homogenization Theory is then applied to convert the behavior from micro to macro scale, using a uniaxial tensile mechanical test for experimental validation. In the numerical model, three microstructures of DP steels developed from the application of three levels of intercritical annealing with temperatures of 720ºC, 740ºC and 760ºC were evaluated. The predictions of the stress-strain curves were analyzed according to the influence of the size and positioning of the RVE. ; O aço dual phase tem se destacado na classe dos Aços ...