The Effect of Shot Peening and Polishing on the Pitting Corrosion Resistance of Stainless Steel

Abstract

An experimental work was performed to study one of the major problems encountered in industry (i.e., pitting corrosion), which cost the industrial world billions of dollars every year. Stainless Steel 304L sheets were used in the present study, the main reason for using stainless steel is their corrosion resistance and it is the most widely used in process industries, but that is not always trouble free. It suffers localized attack in specific environments, which can lead to catastrophic unexpected failures. Resistance to pitting corrosion can be greatly increased by a cold working process called shot peening and polishing. The main objective of shot peening is to induce compressive stresses on the metal surface to operate the tensile stresses that lead to cracking, while the objective of the polishing is to make the surface very smooth and soft and that may induce the compressive stresses on the metal surface and eliminate the microscopic scratches during manufacturing processes. Shot peening and polishing can prevent or retard pitting and cracking, leading to economic saving as a result of longer equipment life. The experimental work is conducted to evaluate the effect of polishing and shot peening in preventing the initiation of pitting corrosion and cracking on the 304L stainless steel under the nitric acid and NaCl environments. The results obtained showed that shot peening and polishing can be beneficial in decreasing the pitting corrosion on stainless steel 304L, also the results showed that using the high quality polishing proved to be the best inhibiter for Stainless steel corrosion.