**Abstract**

In the present investigation mechanical properties of austempered ductile iron (ADI) joints have been studied using two developed electrodes containing with and without Ce content and co-related between microstructure and mechanical properties. Austenitization was done at 900°C for 2 h and austempering at 300 and 350°C for 1.5, 2 and 2.5 h holding time. At 300°C microstructure shows needle shaped bainitic ferrite with lower amount of retained austenite indicate higher hardness and lower impact toughness. However, at 350°C shows feathery shaped bainitic ferrite with higher amount of retained austenite to demonstrate lower hardness and higher impact value. Both the welded joints at both austempering conditions tensile samples broke from the base metal indicates 100% joint efficiency. Fatigue life was varied with varying the austempering temperature and shows higher fatigue life at 350°C austempering temperature presence of higher amount of retained austenite and finer the bainitic ferrite size with smaller graphite nodules. Ce in weld metals to refine the microstructure and shows higher impact toughness and fatigue strength with lower hardness value at both austempering temperatures.

**Keywords:** heat treatment, microstructure, tensile test, Charpy impact, high cycle fatigue
