Surface defects such as streaking are often present on anodized extrusions of 6xxx series alloys. The streak defect is the result of a difference in intensity and diffuse nature of the reflected light compared
to the surrounding material, and is caused by an inhomogeneous distribution of surface imperfections produced during etching. Hence, the etching treatment is an important process step to influence the
formation and severity of streak defects on aluminum extrusions.
By Hanliang Zhu*, Malcolm J Couper**, Arne KDahle**