Use of EPR test to study the degree of sensitization in resistance spot welding joints of AISI 304 austenitic stainless steel

The degree of sensitization (DOS) in resistance spot welding (RSW) joints is considered as the combined effect of intergranular corrosion (IGC) and transgranular corrosion (TGC) in the heat affected zone (HAZ) and of interdendritic corrosion (IDC) in the weld nugget (WN). The DOS is evaluated from electrochemical potentiokinetic reactivation (EPR) tests. The application of EPR test to RSW joints is optimized and an electrochemical minicell is used to study the effect of heat input on IDC in the WN.

Research highlights
► The DOS is the combined effect of IGC and TGC in the HAZ and of IDC in the WN.
► IDC decreases with increasing heat input.
► IGC increases with increasing heat input.
► TGC increases with decreasing heat input.
► The lack of reactivation occurs when DOS does not reach a reactivation threshold.