Plastic Deformation of Galvannealed Coating in Compressive Stress
Keiji MUNEKANE, Yoshinari NUNOMURA, Takayttki TAKASUGI
Deformation response such as plastic deformation in galvannealed coating layer under Vickers indentation, uniaxial compression and rolling deformation was investigated by scanning electron microscopy and X-ray diffraction analysis for measuring half width value of diffraction peaks. In the region around Vickers indentation hole, initiation and subsequent propagation of the cracks were not observed but extrusively developed protuberance was observed. This result suggests that plastic deformation caused by the Vickers indentation takes place in the coating layer. In uniaxial compression and rolling deformation, thickness reduction of the coating layer paraborically increased with increasing specimen (coating+Fe-substrate) reduction, suggesting that macroscopic plastic deformation takes place in the coating layer. Also, it was found in these deformation modes that the interface between coating layer and Fe-substrate changes to irregularly shaped plane as the deformation increases, accompanied with many cracks in the coating layer. By the X-ray analysis for the specimens subjected to uniaxial compression and rolling deformation, it was shown that the apparent plastic deformation takes place not only in δ1-phase layer but also in Γ-phase layer.