Abstract
In this work, two advanced high-strength steels (AHSS) have been developed by designing alloy systems with suitable alloying elements, Mn, Si, Al, and Cr, and postforming heat treatment processes. Thermomechanical process of similar to 90% forging reductions has been applied on the designed alloys at a temperature of 1100 degrees C, followed by austenitizing above A(C3). Four cooling rates, air-cooling, air-cooling with tempering, oil quenching with tempering, and water quenching with tempering, have been applied on the forged samples. The results revealed that the estimated tensile properties of the ferrite/bainite microstructures of alloy A, without Cr, is situated between the bands of the first and the current third generation AHSS, whereas the estimated properties corresponding to the ferrite/fine bainite with 8% retained austenite of alloy B, with Cr, is overlapped with the properties exhibited by the current third generation of AHSSs. The thermomechanical process conducted on the alloy containing Cr has developed steel with tensile strength up to 1790 MPa.