Development of High Strength Hot Rolled Steel to Be Applied for Flanging Deformation

A 50 kg/mm² tensile strength level and an extremely high flangeability were achieved in a developed steel. The steel had a base chemistry of C=0.04%, Mn=0.85%, Nb=0.015%, and S=0.001%, and was processed with a hot rolling finishing temperature of 860 °C and a coiling temperature of 550 °C. This high flangeabilty was attained by reducing S content below 0.002%, as well as reducing carbon content. Elongation results could not be directly correlated to the flangeability of steel. A steel's flangeability has been found to be associated with microvoid distribution in the “as punched” condition. The developed steel exhibited the lowest density, and the smallest size, of microvoid.