The effect of temperature and volume fraction of mahoni (<i>Swietenia mahogani</i>) wood charcoal on SS400 steel using pack carburizing method: Study of hardness and microstructure characteristics

Surface hardening process is one of the final steps to improve the product quality especially in toughness of the steel core. In this study, the SS400 steel was investigated as the potential steel core to be used as a sprocket. However, this material is categorized in low hardness due to its low carbon content. Improving SS400 steel by using surface hardening was carried out by pack carburizing with Mahoni Wood Charcoal (MWC) powder as carburizing. The volume fraction of MWC was varied at 60, 70, and 80% with ratio mixing of BaCO₃ activator for 40, 30 and 20%, respectively. The pack carburizing process was conducted at 850 and 900 ℃ with holding time for 1 h followed by quenching. The hardness test showed that the highest hardness value was 677.4 HV at variation of 60% MWC + 40% BaCO₃ on 900 ℃ (holding time 1 h). This hardness value number of the sample (60% MWC + 40% BaCO₃ on 900 ℃) was higher than raw materials for 452% of raw material. The microstructures also display a martensite structure in this sample.