Majority of microbiologically influenced corrosion failure cases is reported at or near welds. Experiments on bacterial attachment on AISI type 304 stainless steel welds and base metals were carried out to investigate whether factors other than surface roughness influence the attachment. Coupon exposure studies were done using two heterotrophic bacteria Pseudomonas sp. and Bacillus sp. isolated from MIC failure cases. Results showed that bacteria colonized more on weld metal coupons than on basemetal. Experiments that addressed the role of grain boundary/austenite-ferrite interfaces on bacterial attachment showed that initial attachment occurred along the grain boundary/austenite-ferrite interfaces, suggesting the influence of microstructure. Elemental segregation during welding and/or differential energy distribution between matrix and grain boundaries were suggested as the possible reasons for this pattern of attachment. Mitigation of bacterial attachment by altering the alloying element composition and microstructure is discussed.

Subject
Grain size, Microstructure, Steel coupons, Welding, Bacillus, Base metals, Bacteria, Corrosion coupons, Grain boundary, Grain, Weld metal, Microbiologically influenced corrosion, Coupons
Keywords:
stainless steel welds, Pseudomonas sp, Bacillus sp, bacterial attachment, microbiologically influenced corrosion, substratum microstructure
Government work published by the Association for Materials Protection and Performance (AMPP) with permission of the author(s). Positions and opinions advanced in this work are those of the author(s) and not necessarily those of AMPP. Responsibility for the content of the work lies solely with the author(s).
2004
GOV
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