Effect of plasma nitriding on corrosion behaviour of AISI 4330 low alloy steel

Plasma nitriding is a surface treatment process, which is widely used to improve wear, fatigue and corrosion resistance of the industrial parts. In this study, the corrosion behaviors of plasma nitrided and untreated AISI 4330 steel samples were compared. Plasma nitriding of conventionally heat treated AISI 4330 steel samples were performed at 480 °C and 500 °C for 5, 8, 10 and 14 h. The treated samples were characterized using metallographic techniques, SEM, micro-hardness and potentiodynamic tests. The corrosion tests were carried out in 3.5 % NaCl Solution. The result shows that, the corrosion resistance and surface hardness of the AISI 4330 steel increased with an increase in plasma nitriding time and temperature. The plasma nitriding raises the surface hardness up to 830 Hv. The case depth was found to increase with increase in nitriding time and temperature. The reasons for increase in corrosion resistance have been discussed in this paper.