Microstructure and electrochemical behavior of stainless steel weld overlay cladding exposed to post weld heat treatment

Microstructure and electrochemical behavior of stainless steel weld overlay cladding exposed to post weld heat treatment (PWHT) were investigated, wherein pitting and intergranular corrosion behaviors of the cladding material were evaluated by potentiodynamic polarization and double loop electrochemical potentiokinetic reactivation methods. The results indicated that inclusions, multiple element (Mn, Si, and Al) oxides distributed randomly in the cladding material with a size less than 1 µm. PWHT contributed to carbides precipitation along the δ/γ phase interface and the formation of Cr-depleted zone in the austenite phase. Inclusions acted as the pitting sites in the sample as welded. PWHT reduced the pitting potential and contributed to the formation of larger and deeper pits, which nucleated around the δ/γ phase interface primarily. Existence of carbides and Cr-depleted zone dominated the loss of intergranular corrosion resistance after PWHT.