Abstract
High chromium irons are well known for their good wear resistance. Since they are brittle, they tend to fracture under impact. Hence, there is a need to improve the impact property with minimal reduction in wear characteristics. Towards this end, manganese, known for its tendency to retain austenite and containing 5 and 10% in chromium (∼16–19%) irons has been tried. Since the mechanical properties are microstructure sensitive, the castings are made in both metal and sand moulds followed by thermal treatment. The as-cast and heat-treated samples are examined microstructurally and then evaluated for hardness, and impact properties. While the hardness decreases with increase in manganese content from 5 to 10% irrespective of the sample condition (i.e., mould type/heat treatment adopted), the impact property shows two different trends. The 10% metal cooled manganese bearing sample exhibits higher values compared to the 5% ones. On the other hand, for the sand case, 5% manganese shows higher impact energy compared to the 10% ones. Thus, there is a reversal in the impact behavior for the same level of increase in manganese content for these two cases. These findings are correlated with the structural features noticed through microscopy.
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