Enhancing Corrosion Resistance of Stainless Steel 304

Using Laser Surface Treatment

I.M. Ghayad1, M.A. Shoeib2, T. Mattar2, R.M AbuShhaiba2 and H.M. Hussein2

1Faculty of Science, AlAzhar University, Cairo, Egypt

2Central Metallurgical Research and Development Institute, P.O. Box: 87, Helwan, Cairo, Egypt

Abstract

Stainless steel AISI 304 was laser treated to enhance corrosion resistance and improve surface properties. This alloy has many applications in auto industry (car body) as well as oil and gas industry. Different conditions were applied in the laser surface treatment, namely: laser power density, scan speed, distance between paths, medium gas (air, argon and nitrogen). After laser treatment, the samples microstructures were investigated using optical microscope to examine microstructural changes due to laser irradiation. Specimen surfaces were investigated using XRD, SEM and EDAX before and after laser treatment to examine the surface composition changes brought by laser irradiation. Results showed that laser irradiation enhances the corrosion resistance of AISI 304 Stainless steel to a large extent. Corrosion rates as low as 0.011 mpy for laser treated samples were obtained in comparison to 0.952 mpy obtained for the untreated samples. Superior pitting corrosion resistance was obtained under specific treatment conditions. The enhancement of corrosion resistance depends on the laser irradiation conditions. The corrosion protection afforded by laser treatment is attributed mainly to the grain refinement of the top surface layer. This layer is found to consist of nano-scale grains.