Reduction of austenite-ferrite galvanic activity in the heat-affected zone of a Gleeble-simulated grade 2205 duplex stainless steel weld.

• TIG Welding causes significant changes in morphology and chemical composition of the phases in the heat affected zone (HAZ). • Thermo-mechanical simulation was used to study the effects of the thermal parameter on the microstructure evolution in the HAZ. • Electrochemical polarization showed the different passivation behaviour of the phases in the HAZ. • Surface potential surveys revealed the reduction in internal galvanic activity in the duplex HAZ. A Gleeble-simulated microstructure of the heat-affected zone (HAZ) of tungsten inert gas (TIG) welded grade 2205 duplex stainless steel (DSS) has been produced. Local changes in microstructure chemistry were correlated to galvanic activity using scanning Kelvin probe force microscopy (SKPFM) and electro-chemical polarization. The simulated HAZ had a marked reduction of SKPFM measured Volta potentials. This was reflected in a clear reduction of the electrochemical potential difference of the activation peak between the ferrite and austenite phase. The implications of these observations are discussed for reducing the likelihood of environmentally assisted cracking. [ABSTRACT FROM AUTHOR]