Influences of graphite shapes on wear characteristics of austempered cast iron

Dry slip–rolling contact wear test and wet slip–rolling contact fatigue test of several austempered cast irons with various graphite shapes were conducted by using a Nishihara-type wear-testing machine. The influences of the graphite shapes on the wear and fatigue characteristics of cast iron were investigated. Changing graphite shape from spheroidal to flake was found to result in a considerable increase in wear loss in both dry and wet conditions. Decrease in graphite nodularity results increase in wear loss at the initial wear stage. It is because lower graphite nodularity results in a shorter average matrix distance between graphites and also a larger stress concentration factor at graphite tips. The pitting phenomenon is easier to occur in sample with lower graphite nodularity.