Structural Characterization and Mechanical Properties of Ductile Iron - Enhanced Alloyed Ductile Iron

Abstract

In this study, an attempt has been made to produce ductile iron or spheroidal graphite iron and to study its important properties with a view to reduce the import of machinery parts made of ductile iron. Locally available compressor scrap (i.e. the compressor cylinder) which is made from grey cast iron was used to produce ductile iron using a crucible furnace that is fired by oil. Also, recycling of the grey cast iron to ductile iron was investigated and its effect on the microstructure, chemical composition, mechanical properties and chip shape. The mechanical and structural characteristics of the ductile irons that alloyed by the supplement of Ni, Mo, Mg, and Cr were studied In this study, four kilograms of the scrap were charged into an oil-fired crucible furnace. The scrap was heated to 1400°C with using a temperature controller to monitor the temperature with an inserted thermocouple. For desulphurization, the mixture of 3 wt.% burnt lime with 1 wt.% fluorspar of scrap weight was added to the molten at 1400°C by direct tapping into the molten. Then, 2.75 wt.% nickel element, 0.75 wt.% ferromolybdenum and 0.5wt.% ferromanganese of the scrap weight were added. Also, 1.25 wt.% spheroidizing alloy (FeSiMg9) and 1wt.% inoculant alloy of scrap weight were used to treat the iron melt at 1450°C. The analysis of scrap sample and product sample was done to determine their chemical composition, tensile strength, impact strength, hardness, and microstructure. The scrap and the as-cast product analysis determine its chemical composition, tensile, impact, hardness and microstructure. The microstructures revealed that the scrap contains flake graphite and the as-cast product contains spheroid graphite. An increase of the ultimate tensile stress (537.17 MPa), elongation (10%), hardness value (480.4 HB) and impact value (11.21 J) was observed for the alloyed ductile iron as compared with the mechanical properties of grey cast iron scrap, including (247.75 MPa), (6%), (400.3 HB) and (5.66 J), respectively. One of the important conclusions is the plunge container manufactured, and that was used according to the plunging technique followed in this investigation proved successful