The effect of tensile deformation on crack and corrosion resistance of Zn-Al-Mg coating
The Zn-Al-Mg coating steels are important materials for the corrosion protection of steel sheets.However,the Zn-Al-Mg coatings should undergo various deformations in use,so it is very important to study the effect of deformation on the crack and corrosion resistance of coatings.In this work,the effect of 10%and 20%tensile deformation on the Zn-1.6%Al-1.4%Mg alloy coatings with coating weight of 275 g/m2 was studied.Scanning electron microscopy(SEM)and optical microscope(OM)were utilized to observe the crack of the coatings.The crack width of 10%strain specimen was 9.5 μm and that of 20%strain specimen reached 15.4 μm,and both of them have some cracks through the coating to the substrate.Binary eutectic phases containing more MgZn2 became the origin of the crack.The electrochemical test and neutral salt spray test show that with the increase of strain,the corrosion current and corrosion weight loss of the coating increased,but the red rust time was shortened.The crack accelerates the electrochemical reaction during the initial corrosion.