Flow behavior of high strength steel TRB at elevated temperature

In order to simulate the hot stamping process of high strength steel tailor rolled blank (TRB), a proper constitutive behavior needs to be determined to describe the relationship between the thermodynamic properties of high strength steel and strain rates, deformations and temperatures. Then the material model of high strength steel TRB can be established in the hot deformation process. The stress-strain curve at different temperatures and strain rates can be obtained by the isothermal tensile tests, then the constitutive relationship model of high strength steel TRB at elevated temperature can be established by the mathematical method. At the present, it is still the most reliable techniques with the highest precision. Using Gleeble3500 thermal simulation testing machine, tensile tests were carried out for B1500HS high strength steel blank in different thicknesses at different temperatures and strain rates. Then the stress-strain curves were obtained with various process parameters, the constitutive relationship of high strength steel TRB was derived by fitting the test data. In addition, other test results were fed back to validate the constitutive model and it showed that the test and fitted results matched very well. Therefore the constitutive relation can be used to describe the high strength steel TRB stress-strain relationship, which lays a foundation for numerical simulation of the hot stamping process for high strength steel TRB in the future.