Long-term marine immersion corrosion field trials of simulated steel weld HAZ

Corrosion deterioration will cause the actual structural safety of an asset to decline, slowly, with operational use and with time. Moreover, welded areas of such assets have been shown to corrode at an even higher rate compared to adjacent base metal. Yet, controversy still remains as to a more appropriate and accurate representation of the phenomena. This paper reports on a long-term investigation of the effect of weld heat affected zone microstructural variation on corrosion rates. Commercial normalized fine grained steel was heat treated in order to produce samples with a homogeneous microstructure representative of a specific region of a Heat Affected Zone. Immersed for a total of 12 months in temperate natural seawater, corrosion trend loss results for the samples reinforce earlier observations that microstructural changes induced within the heat affected zone do result in relative differences in corrosion rate. Reasons and implications are discussed within.