Relationship between (00.2) and (20.1) texture components and corrosion resistance of hot-dip galvanized zinc coatings

Abstract

Abstract Hot-dip galvanized coatings have attracted increasing interest from the automobile industry and steel producers because of their excellent corrosion resistance. Texture is an important factor, which affects the coating properties. Chemical composition of the zinc bath can strongly influence the texture of hot-dip galvanized coatings. In this study, lead content of the zinc bath was changed from 0.01 to 0.11 wt.%. Specimens were prepared from zinc baths with different lead content and their texture was evaluated using X-ray diffraction. Corrosion behaviour of the specimen was analyzed by Tafel extrapolation and salt spray tests. Cross-sectional studies were performed using optical microscopy. Also, the spangle size of the specimens was determined using line intercept method. From the experimental results it was found that (00.2) basal plane texture component would be weakened by increasing the lead content of the zinc bath and coatings with strong (00.2) texture component have better corrosion resistance than the coatings with weak (00.2) texture component. In addition, the increase in lead content of the zinc bath would strengthen the (20.1), (10.3) and (10.0) texture components and stronger (20.1) high angle pyramidal plane texture component would decrease the corrosion resistance of the coating. Furthermore, spangle size and number of dull spangles would be increased by increasing the lead content of the zinc bath. Finally, it was found that increasing the lead content of zinc bath has no effect on the phases detected in corrosion products.