The Effect of Pulse Plasma Treatment on the Corrosion Resistance of AISI 4140 Steel

Pulse plasma treatment is a surface modification treatment process, which is widely used to improve wear, fatigue and corrosion resistance of the industrial parts. The paper presents the results obtained from an experimental work investigating the changes in corrosion and microstructural surface properties of AISI 4140 steel. For the pulse plasma treatment, a battery capacity of 800 mu F, and three different sample plasma gun nozzle distances were used. The samples were subjected to micro-hardness measurements and it was found that the hardness values of modified surfaces are four times higher than untreated samples. The modified surface layers were examined using an optical microscope and X-ray analyses were carried out all samples. The new phases were found on surface. The samples were exposed to corrosion test in 0.5MNaCl aqueous solution. The corrosion behavior of samples was determined. An attempt was made to establish an empirical relationship between corrosion resistance and parameters of pulse plasma. The presence of modified layer has improved to corrosion resistance, and it was observed that corrosion cracks were initiated dominantly under the modified layer by pit formation mechanism.