12th International Conference on Zinc & Zinc Alloy Coated Steel Sheet - GALVATECH 2021

In order to meet the increasing demand for a flawless and attractively painted car, surface topography of sheet metal is becoming more and more into focus of optimization. Besides inhomogeneous painting, disturbing surface texture with long wavelength proportions can make the appearance of a coating disturbed and inferior. In order to measure and display these inhomogeneity’s, new characteristic values such as the Wsa1-5 value or the Wa0.8 value were introduced with the aim of characterizing surfaces and evaluating them to predict the resulting effect on the final painting. The measured values consider the proportion of long wavelength structures in the topography and provide information about the wave height. However, not only the surface, but also the material plays an important role in meeting the highest painting requirements. In addition, forming conditions during component production can create and reinforce visible textures. This effect is associated with an increase in waviness and is a result of material inhomogeneity, which can be found along the sheet metal cross-section and inside the sheet metal plane. Thereby a direct dependence between the waviness values and material isotropy is deduced. This results in a direct dependence between the waviness values and material isotropy. The article explains the identified relationships between texture characteristic and material isotropy in a typical steel for the automotive industry.