This study evaluated the crevice and pitting corrosion characteristics of the Gas Tungsten Arc (GTA) weldment of N-added 4.5% Mo austenitic stainless steels(UNS S34565). Both the Critical Crevice Temperature (CCT) and Critical Pitting Temperature (CPT) of GTA weldments were evaluated in a 6%FeCl3+1%HCl solution simulating a high chloride content and low pH-value condition in which the alloy is used, such as flue-gas desulphurization (FGD) systems incorporated into a power plant. Considering the importance of the geometric factor in the crevice and pitting corrosion behavior of the as-welded structures, the local corrosion characteristics of weldments including the Heat Affected Zone (HAZ) were electrochemically evaluated by using a potentiostat employing the cyclic polarization method. For this purpose, a selected area of the as-welded specimen was exposed to the corrosion media for the potentiostat scanning, which provided a better understanding of the corrosion susceptibility of the weldment. The microstructural change in the weldment was also evaluated to study its effect on the local corrosion characteristics of the weldments.

Subject
Weld attack, Cyclic polarization, Filler metals, Weldments, Welding, Base metals, Crevices, Pitting, Corrosion resistance, Corrosion coupons, Stainless steel, Elements, Weld metal
Keywords:
critical crevice temperature, critical pitting temperature, weldment, cyclic polarization test, N-added 4.5% Mo Austenitic Stainless Steels
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2002
Association for Materials Protection and Performance (AMPP)
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