Improvement of Surface Properties of Low Carbon Steel by Nitriding Treatment

This work aimed to improve the physicochemical properties of a low carbon steel C15 by a nitriding treatment in a salt bath at 580°C. The micrographs of treated sample show that the nitriding treatment causes significant structural changes, it is allowed to delineate the nitriding layer. The X-ray diffraction and the Raman spectroscopy of the treated samples permitted to identify different nitrides (Fe_{2-3}N, Fe₄N) formed. The obtained hardness profile determines the nitriding depth. Potentiodynamic curves show that the corrosion current density of treated C15 is the 10 times lower than untreated specimen. The values of impedance parameters obtained after nitriding treatment indicate that the resistance values and exponent n increase, whereas the capacitance decreases. We concluded that the nitriding treatment is an effective method for improvement of the corrosion behavior and surface properties of the low alloy steel C15.