Effect of Ferrochrome Addition on Wear and Hardness Properties of Grey Cast Iron

The use of a pair of grinding discs in a domestic milling machine for food processing is commonly practiced in sub-Saharan Africa. During the milling machine operation, the pair of grinding discs wears off gradually by shear and produces metallic particles that contaminate the processed food. This study aimed to reduce these metallic impurities by adding chromium (Cr) to the melt in producing discs to increase the discs' toughness and wear resistance. Cr in the form of ferrochrome (FeCr) was added in weight percentage of grey cast iron to produce alloyed specimens. The control specimen was produced from 40% grinding disc and 60% engine block scraps. Four other experimental specimens were added with FeCr to increase the amount of Cr in subsequent castings. The specimens were prepared and subjected to compositional, phase and microstructural analyses, and hardness and wear resistance tests. The results showed that percentage variations of FeCr in the casts had significant effects on the properties investigated. The addition of FeCr to the melt increased the wt.% amount of Cr and intensity of the phases in X-ray diffractometer patterns for the alloyed cast irons. An increase in the amount of Cr led to an increase in hardness and a reduction in wear rate. Consequently, about 67% reduction wear rate index with moderate hardness was observed in the alloyed casts than the control sample. Thus, the addition of FeCr produced alloyed specimens that would lessen the number of metallic contaminants and frequency of regrooving the grinding discs.