Non-linear strain path experiment and modeling for very high strength material

Abstract

The goal of this work is to develop experimental methods and modeling of very high strength steel sheets subjected to non-linear strain paths. A 1.6 mm thick TRIP steel sheet with a tensile strength of 1180 MPa was investigated. A suitable test for the uniaxial tension pre-strain was developed. A constraint was to achieve an as uniform as possible strain field over the entire gauge area. The pre-strain was conducted on a 500kN MTS tensile testing machine. The geometry of a new specimen was optimized through finite element simulations and experiments on the TRIP1180 material. Then, different types of subsequent specimens were extracted from the pre-strained material by electro-discharge machining (EDM) for the second deformation step leading to a strain path change. The subsequent plastic behavior was measured and modeled using the HAH distortional plasticity model. Comparisons between the experimental and predicted behavior are discussed.