On the Work-hardening Description of Low Carbon Steel Sheets by a Microstructure Based Model 2014-36-0179

The work-hardening of three common automotive low carbon steel sheets is described in terms of two different types of microstructure based models. The first model employed is the classical Kocks-Mecking model. On the other hand, the second model incorporates the effect of the density evolution of non-redundant dislocations, also known as Geometrically Necessary Dislocations (GND), into the Kocks-Mecking hardening law. Each of both models was coupled to a Taylor-type crystal plasticity framework in order to follow the dislocation density evolution over all slip systems. One of the microstructural parameters employed on the calibration of the second model is the density of GND, parameter which was experimentally acquired from crystal orientation maps by EBSD (Electron Backscatter Diffraction) on the tensile samples. Both models displayed satisfactory results on describing the experimental work hardening behavior of the steel sheets, despite the classical Kocks-Mecking showed a better fitting to the stress-strain curve. Finally, the work hardening description was evaluated by comparing the present models with the empirical equations of Hollomon and Ludwik.