Microstructure Characteristics, Mechanical and Corrosion Properties of Copper Alloyed Hypo-Eutectic Grey Cast Iron

Abstract

In this study, influence of varied copper addition on the mechanical properties and corrosion characteristics of grey cast iron (GCI) was investigated. As-cast unalloyed and 0.035 wt. %, 0.65 wt. % 0.85 wt. % and 1.18 wt. % copper alloyed GCI samples were produced using rotary furnace. Chemical compositions of the samples were determined by Optical Emission Spectroscopy using ARL QuantoDeskSpectro analysis machine. Tensile and hardness measurements were made using INSTRON tensile testing machine- model 3369 and Universal Rockwell hardness testenr- model 8187LKV respectively. Samples’ characterization was done using Philips SEM (XL30 TMP). And electrochemical measurement was determined using AUTOLAB PGSTAT 204N instrument. From the results, the as-cast unalloyed, 0.035 wt. % and 0.85 wt. % and 1.18 wt. % Cu alloyed GCI samples revealed lamella graphite in pearlite matrix, short flake graphite in pearlitic-ferrritic matrix, Type A flake graphite in pearlitic-ferritic matrix and long flake graphite in ferritic-pearlitic matrix respectively. Tensile, hardness and elongation properties of the copper GCI samples ranked superior over the as-cast unalloyed GCI sample. Optimum tensile value 158.26 N/mm2 and hardness value 447.4 HRC were revealed by the 0.85 wt. % Cu, and optimum ductility value of 2.79% was revealed by the 1.18 wt. % Cu alloyed GCI sample. In general, copper alloyed GCI samples showed better corrosion resistance relative to the as-cast unalloyed GCI sample. The copper alloyed GCI samples showed better corrosion resistance relative as compared to the as-cast unalloyed GCI sample. Least corrosion rate of 0.0011297 mm/yr with polarization resistance of 174.58 Ω was revealed by the 0.85 wt. % Cu alloyed GCI sample. Hence, it is most suitable in application requiring high to moderate strength is marine environment.