用装配3点弯曲试验装置的扫描电镜原位分析了GA钢板变形情况下镀层中裂纹的产生、扩展、镀层断裂及GA钢板在塑性变形过程中镀层与钢基体界面交互作用的情况。试验及分析结果表明：镀层承受拉应力的一侧，裂纹在Г/δ1相界面处产生，在δ1相中沿着垂直于镀层平面的方向扩展，并沿着Г相/钢基体界面延伸，镀层塑性变形的迹象不明显；镀层承受压应力的一侧表现出了明显的塑性变形，存在裂纹之间的相互作用和不均匀变形情况。合金化镀层无论承受拉应力还是压应力，镀层主要的破坏形式是断裂，而与镀层相接触的钢基体的主要破坏形式是局部不均匀塑性变形。
The generation and expansion of the cracks on the galvannealed coating and the fracture of coating were analyzed when it is under compressive or tensile stress, and the interaction between the coating and the steel substrate during galvannealed deformation was also analyzed in a scanning electron microscope (SEM) with in-situ investigation method under three-point bending test. The results show that, when the galvannealed coating subjected to tensile stress, cracks occurred at the Г/δ1 interface and extended perpendicularly to coating plane in the δ1 phase. Then, cracks reached and propagated along the Г/Fe interface, the signs of plastic deformation of coating were not obvious, but showed apparent plastic deformation under compressive stress, there was substantial interaction and inhomogeneity. Irrespective of compressive or tensile stress, the major deformation mode in the galvannealed coating was cracking while that in the steel substrate was inhomogeneous plastic deformation adjoining to the coating.
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