Microstructure and mechanical properties analysis of dual-phase lateritic steel as an alternative for SAE 3120 steel substitution

Lateritic steel has very wide potentials in various applications so that needs to be explored. This research aims to determine the characteristics of microstructure and mechanical properties of lateritic steel through the heat treatment process which referred to the SAE-3120 standard. Two lateritic steels with similar chemical composition were prepared to be heated with a temperature of 975 °C (MBL-A) and 840 °C (MBL-B), respectively. Every step of heating followed by rapid cooling using water. Based on microstructure observation, the martensite phase has existed on the MBL-A specimen and the dual-phase ferrite-martensite was successfully formed on MBL-B specimen. Furthermore, the mechanical properties consisting of strength, hardness and toughness value have been obtained. The results revealed that MBL-B with ferrite-martensite phase gives the benefit of mechanical properties combination between hardness, strength and toughness namely 52.38 HRC, 1630 MPa, and 27.5 Joule, respectively. It was better than as-cast material, MBL-A and also higher than the SAE-3120 steel. This happens as a benefit of the formation of dual-phase ferrite and martensite.