Abstract
Deformation and fracture in galvannealed coating which was subjected to tensile or compressive stress by three point bend test were investigated by scanning electron microscopy. In the coating subjected to compressive stress, cracks were generated in the δ1 phase and propagated at an angle inclined to coating plane in the δ1 phase. Then, fracture occurred within δ1 phase, or, along the Γ-Fe interface. In the coating subjected to tensile stress, cracks were generated in the δ1 phase and propagated perpendicularly to coating plane in the δ1 phase. Then, cracks reached and propagated along the Γ-Fe interface. The coating did not show any plastic deformation under tensile stress but showed apparent plastic deformation under compressive stress. During deformation of the coating and the steel substrate, there was substantial interaction and inhomogeneity. Major deformation mode in the coating was cracking while that in the steel substrate was inhomogeneous plastic deformation in the regions adjoining to the cracks, irrespective of compressive or tensile stress.
