Corrosion characterisation of laser beam and tungsten inert gas weldment of nickel base alloys: Micro-cell technique

• Grain matrix showed better corrosion resistance than grain boundary.
• Microcell studies showed distinct corrosion behaviour of individual regions of weldment.
• TIG welding resulted in increased stable anodic current density on weld fusion zone.
• LB welding resulted in high stable anodic current density for heat affected zone.

The electrochemical studies using micro-cell technique gave new understanding of electrochemical behaviour of nickel base alloys in solution annealed and welded conditions. The welding simulated regions depicted varied micro structural features. In case of tungsten inert gas (TIG) weldments, the weld fusion zone (WFZ) showed least corrosion resistance among all other regions. For laser beam (LB) weldments it was the heat-affected zone (HAZ) that showed comparatively high stable anodic current density. The high heat input of TIG welding resulted in slower heat dissipation hence increased carbide precipitation and segregation in WFZ resulting in high stable anodic current density.

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