Influence of Plasma Remelting Conditions on Quantitative Graphite Dissolution and Modified Surface Characteristics in 500-12 Ductile Iron

In this study, the influence of multi-pass plasma remelting conditions on quantitative graphite nodules dissolution, surface hardening and wear resistance of 500-12 ductile iron was evaluated. Surface remelting was carried out at various levels of heat inputs using high-temperature plasma beams. The graphite dissolution was uniquely quantified via image analysis approach, and then the remelted surface layer was characterized for phase transformation, microstructure, hardness and wear resistance. The remelting process parameters (arc current and scanning speed) showed significant (p < 0.01) influence, both on graphite nodules dissolution and surface hardening. Consequently, microstructure of the treated layer is modified and the surface exhibited a significant improvement in hardness and wear resistance. In addition, treatment conditions having slower scanning speed showed better surface modification. Therefore, the plasma remelting enhanced surface hardness and dry sliding wear resistance of 500-12 ferrictic ductile cast iron, which makes it suitable for application in a severe wear condition.