Doaa El-Zeer, Journal of Engineering Research and Applicationwww.ijera.comISSN : 2248-9622 Vol. 8, Issue 10 (Part -IV) Oct 2018, pp11-15 www.ijera.comDOI: 10.9790/9622-081004111511|Page Improvement Of The Corrosion Resistance Of The Stainless Steel With The Plasma Nitridingand The Chemical Polishing As Two Different Mechanisms Doaa El-Zeer a,b a Center of plasma technology, Al-AzharUnivesity, Nasr City, Cairo, Egypt b Taif University, Al-khurmaUniversity College, Physics Dep., KSA. ABSTRACT Two different techniques have been studied to improve the corrosion resistance of the austenitic stainless steel(304L). The first technique is the plasma nitriding using a mixture of N 2 -H 2 gasesand the second technique is the chemical polishing. The potentiodynamic polarization measurements were used to compare between the effects of the two techniques on the corrosion resistance of the stainless steel. The corrosion potential of thenitridedsampleswasimproved by 61% while in the case of the samples that chemically polished it was improved by 13%. X- ray diffraction (XRD) pattern of the nitride sample confirms the formation of Fe 2-3 N, Fe 4 N, and CrNnitridephases and also the formation of the super saturated nitrogen-rich phase "S-phase" which has important role in the improvement of the corrosion resistance. The surface morphology of the two samples confirms the formation of the S- Phase. The grain size of the nitride sample was about 50.25 nm. Keywords: plasma nitriding, chemical polishing, Corrosion, Stainless steels, metastable phase. -------------------------------------------------------------------------------------------------------------------------------------- Date Of Submission:08-10-2018 Date Of Acceptance: 20-10-2018 --------------------------------------------------------------------------------------------------------------------------------------- I. INTRODUCTION Different types of stainless steels have been commonly used in many engineering applications, especially parts in the automotive industry such as crankshaft, gear, pinion, bolt and various machine tool components because they have good mechanical properties and they are easily fabricated. Also, in several services they have been used in corrosive environments such as lubricant, gaseous and liquid environments resulting in reduction of performance and lifetime of those parts. Therefore, the parts require high hardness of surface for increasing corrosion resistance[1].Various Physical and chemicaltechniques were used to improve the properties of the stainless steel. The physical techniques such as Physical Vapor Deposition (PVD), Plasma nitriding, Carbonitriding and Thermal spraying, are widely used to improve their surface in order to achieve better wear, abrasion and corrosion resistance. One the other hand one of the most popular chemical techniques is the chemical polishing.Plasmanitriding is a very promising technique to improve surface mechanical properties of stainless steels[2], and improving their surface corrosion resistance[3].In the present study it has focused on the treatment of the austenitic stainless steel of type (304L) by two different mechanisms; plasma nitriding as a physical techniqueand the chemical polishing as a chemical one. The treatment by the two techniques was repeated three times to ensure the results and the average has taken. The purpose of this study is to compare between the two mechanisms in the improvement of the corrosion resistance properties and discover the importance of the plasma nitriding technique in the improvement of the surface properties of the stainless steel especially the corrosion resistance. II. MATERIALS AND METHODS Materials preparation The material that is used in the present study is the 304L austenitic stainless steel which was cut into small sheets of dimensions 15x 20 x2 mm. Table1 Shows the chemical composition of the austenitic stainless steel 304L material (in weight percent). Fe Cr Ni Mo Co C Si Mn S 71.5 18.05 7.86 0.3 0.094 0.06 0.05 1.147 0.00 5 Table 1 The chemical composition of the austenitic stainless steel 304L material (in weight percent). The surface of the stainless steel samples was mechanically abraded with 400 up to 2000, grit emery papers, rinsed with distilled water, degreased in acetone, absolute ethanol and dried in air. RESEARCH ARTICLE OPEN ACCESS