Stored energy evaluation for high strength dual-phase steels with different pre-annealing conditions

Abstract The purpose of this study was to determine the stored energy of dual-phase (DP) steels after hot rolling, coiling, and cold reduction using electron backscattered diffraction analysis. Three methods for stored energy evaluation were examined and compared: the sub-grain boundary, image quality, and kernel average misorientation methods. The results demonstrated that the sub-grain method, in which stored energy was calculated as a function of sub-grain boundary misorientations and total sub-grain boundary length, can provide more accurate stored energy values, since cold work was responsible for forming numerous dislocation structures such as shear bands, cells, and cell walls. As expected, the steels with the combination of a low coiling temperature of 580 °C and 60 pct cold reduction had the highest stored energy values. This information is important in defining how pre-anneal processing conditions might control the response of DP steels to the various transformations occurring during continuous galvanizing line simulations