Tensile behaviors of IF steel with different cold-rolling reductions

An interstitial-free (IF) steel sheet with a cold-rolling reduction of 75% shows a high tensile strength (710 MPa) while preserving a considerable plastic strain (13%). Both flow stress and tensile stress monotonically increased with an increasing rolling reduction. Interestingly, the uniform plastic strain also increased from 3.6 to 9.2% with increasing the cold-rolling reduction from 13 to 75%. However, a fall in ductility in the specimens with rolling reductions between 13 and 47% was found, which is attributed to the onset of localized shearing resulting in a decrease of elongation-to-failure. The ductility recovery with increasing the rolling reduction up to 75% is related with the decreasing both in lamellar spacings and cellblocks sizes.