Corrosion of Weld Heat-Affected Zones Submersed in Seawater with Indigenous Microorganisms

The corrosion behaviors of different weld heat-affected zones (HAZs) were investigated, comprising an API 5L X65 steel immersed in seawater with abundant native microbial community. Before tests, HAZ physical simulations performed at the peak temperatures 700 °C, 860 1000 and 1350 °C. Throughout 14 days immersion, various planktonic bacterial groups associated microbiologically influenced metabolically active seawater. Desulfovibrio members present a considerable number OTUs. Scanning electron microscopy showed intense adhesion product deposits all sub-regions control base metal coupon (BM). electrochemical tests revealed indistinguishable behavior BM. However, topography analysis pitting corrosion. results manifested that resistance microstructure composed cementite grains (700 °C HAZ) was superior to other sub-regions. On hand, martensite austenite (860 exhibited worst joint, leading maximum pit penetration 2.3 times greater than on changes sub-region sensitivity attributed variations microstructural composition.