Anisotropic 3D growth of corrosion pits initiated at MnS inclusions for A537 steel during corrosion fatigue

The 3D growth behaviour of pits initiated at MnS inclusions for A537 steel under cyclic load condition has been investigated by confocal scanning laser microscope and finite element analysis. The results indicated the growth of pit for cyclic-stressed samples showed anisotropic behaviour. Significant higher growth rate was found in the direction perpendicular to load axis. Finite element analysis indicated that localized plastic strain played an important role on pit growth. The growth kinetics of pit in width direction is dominated by plastic deformation. Coalescences of pits further increase the growth rate of pit as predicted by finite element analysis.