In this research work aluminum nitride (AlN) films were deposited usig only RF reactive sputtering atmossphere of nitrogen and argon on mild steel (AISI 1018). Coatings were deposited on substrates at RT, 200ºC, 400ºC, 500ºC and at 600ºC.The substrate temperatute notably affected the thichness, crystalline grain size, and hardness of the coatings. Use XRD, AFM, SEM, EDX, nanoindentation, salt spray or moisture to check the chemical composition, thickness, roughness, film structure, mechanical and corrosion properties of the film. All samples confirmed excessive hardness values exceeded in some cases, 23 Gpa and Elastic modulus 222 Gpa for 500ºC. AlN with a lattice (a=2.80710 Ǻ) parameter and only developed under conditions of high surface mobility.