Influence of the composition ratio of manganese and copper on the mechanical properties and the machining performance of ductile iron

In the present investigation, we studied the influence of the composition ratio of manganese and copper on the mechanical properties and the machining performance of a ferritic-pearlitic ductile iron. A series of Y-block specimens and stair specimens were casted using different manganese and copper levels. The experiments indicated that manganese can efficiently improve the strength of ductile iron, but the plasticity and machining performance decrease significantly when the manganese content exceeds 0.9%. To obtain high strength castings at low manganese levels, the Mn-Cu alloying treatment was also investigated here. The results indicated that with 0.6%-0.8% of Mn and 0.5%-0.8% of Cu, the tensile strength of ductile iron can be in the range of 600-725 MPa, the elongation can remain above 5.5%, and the machining performance is satisfactory. Furthermore, the distribution of manganese and copper in the ductile iron matrix was also investigated.