Effect of Thermomechanical Processing on Mechanical Properties of Hot Rolled Multiphase Steel

The effect of thermomechanical processing (TMP) on the mechanical properties of hot rolled multiphase steel was investigated. TMP was conducted using a laboratory hot rolling mill, in which three different kinds of finish rolling deformation degrees and temperatures were applied. The results indicate that polygonal ferrite, granular bainite, and a considerable amount of stabilized retained austenite can be obtained by TMP. The stability of the retained austenite increases with decreasing finish rolling temperature and increasing finish rolling deformation degrees. Ultimate tensile strength (σb), total elongation (δ), and the product of ultimate tensile strength by total elongation (σb · δ) for 50% reduction at finish rolling temperature of 700 °C reach maximum values [791 MPa, 36% and 28 476 (MPa · %), respectively].