Variation of Nano Ce Content in Austempered Ductile Iron (ADI) Weld Metal and Its Effects on Microstructure

In the present study, four numbers of coated electrode were developed with and without addition of nano Ce content for welding ductile iron and convert to austempered ductile iron after isothermal heat treatment. Ce contents were varied with three different levels, i.e. 0.05, 0.1, 0.2wt% to understand the effect of Ce content in the weld metal with respect to microstructural properties. Defect-free welds were established by applying preheat and then post weld heat treatment immediately after welding. Austenitization was done at 900 degrees C for 2h and austempering at 300 and 350 degrees C for three different holding time. Microstructural constituents were varied by varying the Ce content in weld metals. The optimum amount of Ce content to refine the microstructure before and after austempering shows a significant effect in the austempering kinetics. Among all three levels of Ce content, 0.1wt% was considered as the optimum level with respect to microstructural constituents and hardness.