Investigation of AISI 1040 steel corrosion in H2S solution containing chloride ions by digital image processing coupled with electrochemical techniques

This paper presents a study of AISI 1040 steel corrosion in aqueous electrolyte of acetic acid buffer containing 3.1 and 31 × 10−3 mol dm−3 of Na2S in both the presence and absence of 3.5 wt.% NaCl. This investigation of steel corrosion was carried out using potential polarization, and open-circuit and in situ optical microscopy. The morphological analysis and classification of types of surface corrosion damage by digital image processing reveals grain boundary corrosion and shows a non-uniform sulfide film growth, which occurs preferentially over pearlitic grains through successive formation and dissolution of the film.

► The use of in situ optical microscopy imaging is useful for the study of corrosion in situ. ► Is possible the observation of sequential images of corrosive processes, such as grain boundary corrosion. ► In situ images offer local information, revealing non-uniform changes on the surface during the corrosive process. ► Sulfide film formation was detected over pearlitic grains.