[[alternative]]Research on the Production of Thin-Wall Ductile Iron Castings

[[abstract]]The primary purpose of this research was to nvestigated the effects of molten metal processing variables on the stepped thin-wall ( 2, 4 and 6 mm in thickness ) ductile iron castings. First, the carbon equivalent ( 4.8 % ) was controlled, the effects of homogeneous microstructure on the stepped thin-wall ductile iron castings with various inoculants, spheroidizer and their addition amount was investigated. Second, at the same carbon content ( 3.9 % ), to study the effects of processing variables, such as, addition amount of Si, type of inoculants and its addition amount, spheroidizing treatment, solidification cooling rate and mold coating on the microstructure and mechanical properties of the thin-wall ductile iron castings. The experimental results show that production of the thin-wall ( 2 mm in thickness ) ductile iron castings with carbide fraction less than 5 % was successful by using green sand mold at higher ( 4.6 % ~ 4.8 % ) carbon equivalent. To get thin-wall ductile iron castings with better homogeneous microstructure and mechanical properties, the processing variables are carbon equivalent under 4.66 % ( 3.67 % C, 2.97 % Si ), mold cavity with graphite coating, adding 1.0 % inoculant S-70 and 1.0 % spheroidizer C. G. The nodule count and nodularity of the castings with 2mm thickness can be up to 2673/mm2 and 90%. The ferrite fraction of matrix can be up to over 76 %, the carbide fraction under 5 %, the average ultimate tensile strength up to 56 kg/mm2, and 7 % elongation.