Heat Affected Zone (HAZ) is the area where one or more changes from the starting state to the solid state engaged in heating have occurred as a result of the welding heat cycle. In this study, we attempted to weld Austempered Ductile Iron (ADI) of the initial alloy ferritic matrix using Shielded Metal Arc Welding (SMAW) with an E6013 electrode. A total of six alloys of ADI were austempered at 360 °C for 180 minutes after being austenitized at 900 °C for 15, 30, 60, 120, 180, and 360 minutes. An optical Microscope (OM) and an image-processing technique characterized the weld joint's microstructures. The microstructure of the partial fusion zone (PFZ) has nodular graphite, pearlite, and a small fraction of martensite; the austenite transformation zone (ATZ) consists of nodular graphite plus pearlite. Only a part of the austenitic- ausferritic matrix can transform to austenite at the repeated transformation zone (RTZ). No obvious change in the microstructure at the base metal zone (BMZ).