For standard motors, the most used heating treatment for rotor laminates is the so-called “bluing” process. This process takes place in a furnace with wet atmosphere, where a thin iron oxide layer is, precipitated on all rotor laminates surfaces, including the internal surfaces of slots. Since it is common and very convenient to use such furnace at the same time for rotor annealing, its temperature is limited at 450 °C to avoid geometrical distortions in the finished rotors. The quality of oxide layer in “blued” rotor laminates is poor when compared to that obtained in controlled atmosphere (N2