Application of FEG-SEM and EBSD Methods for the Analysis of the Restoration Processes Occurring During Continuous Annealing of Dual-Phase Steel Strips

Abstract

The paper presents results of the investigation aimed at the identification both qualitative and quantitative characterization of changes occurring in the structure of cold rolled DP steel during annealing in temperature range 600–700 °C. The investigation was conducted mostly by means of scanning electron microscopy combined with EBSD method. In the study, mechanisms of processes leading to subgrains formation related to static recovery, as well as to the processes connected with formation and growth of new grains in the examined material, which is characteristic feature of static recrystallization, were described. The role of the Fe3C carbide dissolution was examined which is crucial at the initial stages of as cold rolled structure transformation into austenite. Significance and the limitations of the parameters determined in EBSD analysis, such as IQ, KAM, GAM, and GOS for the quantitative characterization of the changes occurring in the structure were analyzed. These parameters are very important both for the qualitative and quantitative analysis of the structural changes occurring. They allow, among others, for determination of the fraction of deformed substructure subject to restoration processes during annealing. Examples illustrating the significance of these parameters and constraints on the analysis of recovery and recrystallization processes are presented.