Chiang Mai Journal of Science

     Research has been carried out to eliminate of the carbide phase (FeMn)₃C at the grain boundaries through a double solution treatment. The process begins, which is heating the steel to a temperature of 1000°C with a holding time of 100 minutes, then hot rolling is carried out by 28%. Furthermore, the steel reheated from room temperature to 1100°C with a holding time of 20 minutes, followed by a double solution treatment process, which is heating the steel gradually from room temperature to 730°C with a holding time of 30 minutes, then heating is continued to a temperature of 1000°C with a holding time of 15 minutes, and quenching by water. SEM mapping shows steel contains Fe, Mn, C, Si and Ni elements. XRD characterization showed that the double solution treatment process did not change the constituent phases in the form of Fe₃O₄, γ-Mn, γ-Fe, α-Fe and MnO₂, but reduce the crystalline size from 0.0247 to 0.0223 μm. Based on optical microscope and SEM observations, it can be seen that the double solution treatment process was also able to reduce the grain size from 5.33 to 1.30 μm and remove the carbide (FeMn)₃C phase at the grain boundaries, as well as successfully change the morphology from cleavage areas to dimple areas.