Effect of Nodule Count on Microstructure and Mechanical Properties of Spheroidal Graphite Cast Iron in Automotive Parts Manufacturing

Abstract

Abstract

This research aims to study the effect of graphite nodule count on the proportions of ferrite and pearlite, mechanical
properties and microstructure of ductile cast iron. The ductile cast iron casting was produced by induction furnace, adjustingcarbon and silicon content for carbon equivalent of 3.95-4.45 %CE, treated with FeSi 4.8%Mg alloy, and inoculated with FeSi-Ba alloys 0.30-0.32 % by weight, using the sandwich method and late stream inoculation. The metal was poured at approximately 1500-1520 oC with different residual magnesium contents. The tensile strength, microstructure of ferrite / pearlite, and nodule
count were mainly determined. The results suggested that the residual magnesium range of 0.065-0.075 %Mg reduced the nodule count to 78 nodules/mm2, with a shape deterioration of spheroidal graphite. This also resulted in reductions in the proportion of ferrite in the structure and the elongation at break. In summary, it can be concluded that the nodule count and the residual magnesium greatly affected the relative amount of ferrite and pearlite in the matrix and the mechanical properties of the ductile
cast iron.