Retained Austenite Rating: In many cases it is considered crucial to determine austenite percent in heat treated steels. This is because of most applications not permitting excessive amounts of retained austenite such as applications where high wear resistance is important. Also for alloys with relatively high nickel content (say 1% or higher) where the austenite phase can be retained in solution and can under stress or mechanical energy (loading) be transferred to un tempered martensite and cause problems. Retained austenite when excessive can also cause grinding burns if the surfaces containing that phase after a heat treat (carburize) operation need to be ground.