Effect of Thermomechanical Treatment on the Microstructure and Mechanical Properties of an IF Steel

This study focused on thermomechanical treatment of an interstitial-free (IF) steel. As-received IF steel underwent cold reduction of 80% followed by subcritical annealing at 680 °C for 10, 20, 30, and 40 min. These cold-worked and annealed samples were characterized using optical microscopy and scanning electron microscopy (SEM). Mechanical properties such as hardness and tensile strength were determined. Fracture surface was studied using SEM. On the basis of resulting mechanical properties and fractographic study, it was concluded that employing annealing time between 20 and 30 min at 680 °C imparts the desired combination of strength and ductility required for deep-drawing applications in automotive industry.