1. In contrast to cast irons with 12–14% Cr, in cast irons with 29–30% Cr transformation by bainitic and martensitic mechanisms is prevalent. 2. With increasing content of carbon and manganese there is an increase in austenite stability in both the pearlitic and intermediate regions. 3. From hardenability diagrams plotted it is possible to select cast iron compositions providing maximum hardness in a given cross section, and consequently, high service properties, e.g., wear resistance.