On the Development of a Metallographic Method to Determine the Strain of Ferrite Phase in a HSLA Steel

In the present work the strains in the ferrite phase of a structural steel were measured using a metallographic method. The steel was a controlled rolled high strength low alloy (HSLA) steel which possessed an obvious banded structure and exhibited considerable anisotropy in plastic deformation. A model is proposed to describe the banded structures and the anisotropy of deformation and on the basis of this model a formula has been derived for calculating the strain of ferrite phase and correlating it with the global strain imposed on the specimen. A metallographic method was used to measure the aspect ratios of 60 grains of each region with different strain levels on a sectioned tensile specimen after deformation.