Concerning the duplex treatment, Huang et al. [9] studied the effect of the nitriding cases on the coating properties, and found that the hardness of TiN coating on plasma nitrided AISI M12 steel was increased due to the improvement on the load carrying capacity of the duplex treated surface. Similar results were found by Ma et al. [10], where the hardness of TiN presented higher values when deposited over a nitrided surface than over non nitrided H13 steel. On the other hand, Ding et al. [11] found that the substrate hardness does not affect the coating hardness, friction coefficient and wear rate, but it does
affect the coating/substrate adhesion. As one can realize it is not very clear if a nitriding treatment increases the coating mechanical properties or simply improves coating/substrate adhesion. In order to clarify the above mentioned issue, it was investigated in this work the mechanical and wear properties of the TiAlN coating with two different thicknesses deposited on two different nitrided cases, and compared with the coating deposited on non nitrided AISI H13 substrate.