On the Microstructural and Mechanical Behavior of a Fe-0.3C-2.3Mn-0.22Si-0.5Cr-0.13Ti-0.005B Steel Intended for Automotive Applications

The automotive industry is avid for improvements regarding the material’s mechanical behavior. Specifically, a better balance of ultimate tensile strength (UTS) and elongation to fracture is desirable for safety enhancement. In this work, steel produced by vacuum induction melting was unidirectional hot rolled (UR) from 1150 to 870 °C. After UR, the plates were processed following two different routes: (1) water quenched (UR + WQ), and (2) water quenched plus a cryogenic treatment at − 180 °C (UR + WQ + CT). The latter route was proposed to completely transform the residual austenite and disperse the chromium carbides (CrxCy) and B-rich precipitates carbides into the martensite matrix. In both conditions, the microstructure revealed the presence of fine martensite with a lath-like morphology and [111]γ habit plane indices. Relatively elevated mechanical properties were found such as a UTS of 1866.7 MPa for the UR + WQ steel. For the UR + WQ + CT condition, a UTS of 1744.8 MPa and an elongation of 30% were obtained. From the toughness exhibited by these steel conditions, they can be considered ideal candidates for the manufacture of automotive body parts such as side intrusion beams and bumper reinforcements.