Modelling Crystallographic Texture Evaluation and Non-Destructive Measurement of Magnetic Anisotropy using an Electromagnetic Sensor in Interstitial Free (If) Steels

Interstitial free (IF) steels are popular in the automotive industry for applications requiring good ductility (formability), strength and a superior surface quality. Magnetic anisotropy measurement can be used to gain information about the crystallographic texture, which is an important property controlling strength and especially the formability, for example rvalues. The crystallographic texture is generated during rolling and subsequent recrystallisation during the annealing heat treatment. A set of IF steel specimens, at different states of recrystallisation (cold rolled, partially recrystallised and fully recrystallised) and accordingly different texture components have been used to investigate measurement and prediction of magnetic anisotropy. A finite element microstructure model that considers crystallographic texture based on magnetic domain theory has been used for the evaluation of magnetic anisotropy in polycrystalline steels. In addition, a laboratory based electromagnetic (EM) U shaped sensor has been proposed to determine the magnetic anisotropy in IF samples by measuring at angles varying from 0° to 90°, in steps of 15°, with respect to the rolling direction. Kernel Average Misorientation (KAM) values from Electron Back Scattered Diffraction (EBSD) characterisation of the samples has been used to evaluate the recrystallisation fraction and correlate that to the texture.