Inverse hardness distribution refers to as-quenched hardnesses that are greater in the core than at the surface. Although this phenomenon is rarely reported, it is not new. One of the first to research and report on this interesting phenomenon for petroleum quenched steel was Tamura and Shimizu. Inverse hardening processes were subsequently modeled and validated by Arimoto. More recently, this behavior was identified and explored by Liscic, Totten and Grubisic for aqueous polymer quenched AISI 1045 and 4140 steels, especially as it related to fatigue effects. In this paper, the cracking and distortion behavior, which has not been reported previously, of petroleum oil quenched AISI 5160 and 6150 steel exhibiting inverse hardening will be discussed.