Microstructure and Hardness Properties of Hardfacing Overlays Deposited by Shielded Metal Arc Welding on Low Carbon Steel Plate

The aim of this study is to investigate the effect of applying various welding current parameters of shielded metal arc welding (SMAW) on microstructure and the hardness of the hardfacing overlays. The investigation was performed on a 12mm thick ASTM A36 steel plate weld overlaid by hardfacing electrode HV-450 of 3.2 mm diameter at various welding currents, 90, 110, and 130 amperes, respectively. The investigation was conducted by using optical microscopy, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and hardness test on the hardfacing overlay. The results showed the hardness of the hardfacing overlay is higher than the base metal, indicating higher strength of the weld overlay. From the three welding currents applied, the highest hardness in the weld overlay is obtained at the lowest current.