Why ADI (austempered ductile iron)?

Tensile Properties	Twice the strength of conventional ductile irons with similar levels of ductility. At a given hardnesslevel, ADI can achieve equivalent tensile strength of steel, but in general it exhibits a slightly lower yield strength and ductility. With high levels of casting integrity and proper heat treatment, the proposed ASTM specifications are usually conservative.
Inpact Strength / Toughness	Fracture toughness twice that of pearlitic ductile irons and nearly the same as wrought steels. Impact properties of ADI and ferritic/pearlitic microalloyed steels are in the same approximate range. At comparable strength levels, the impact strength of heat treated steels is higher than that of ADI.
Fatigue Strength	Fatigue strength of ADI and quench and tempered steels are in the same general range. Fatigue strength of ADI is typically higher than that of the ferritic/pearlitic microalloyed steels.
Wear/Contact Fatigue	Relative to contact fatigue, ADI provides better resistance than cast or through-hardened steels, but not as good as case-carburized steels. ADI grades 200-155-01 and 230-185 exhibit better wear resistance than many steels, although they are not as good as white cast iron. For the more ductile grades of ADI, superior wear resistance is achieved over steels of equivalent strength, because of the ability of the ADI matrix to form strain induced martensite.