Microstructure and pitting behavior of the dissimilar metal weld of 309L cladding and low alloy steel A533B

The microstructure and pitting behavior of a dissimilar metal weld (DMW) of 309L and low alloy steel (LAS) were investigated with various surface analysis techniques and potentiodynamic polarization. The heat affected zone (HAZ) consists of four zones i.e. are heavily etched zone, lightly etched zone, coarse bainite zone and fine bainite zone, respectively. Cr depletion takes place in some δ ferrite/γ boundaries in 309L. Pits prefer to initiate along the δ ferrite/γ boundaries and mainly grows in γ phase, leaving a δ ferrite skeleton.