Multiscale Analysis of the Gold Dust Defect in AISI 430 Industrial Stainless Steels: Influence of the Aluminum Content

The ‘‘Gold Dust Defect’’ affects the surface quality of AISI 430 ferritic stainlesssteels. However, there is a very limited number of studies focusing on it. Tobetter understand its nature, we have combined several techniques, such as xrayphotoelectron spectroscopy, atomic force microscopy, and transmissionelectron microscopy, in order to extract a maximum of structural and compositionalinformation. Our results show that the surface quality,microstructure, and chemistry of the samples are strongly affected by thealuminum content, the severity of the defect being the highest at the lowest Alconcentration. Not only is the concentration of the defects at the surfacestrongly reduced when increasing the Al. at.% but the depth of the cavities isalso reduced by a factor of 3 when the Al content is increased from 0.09 at.%to 0.59 at.%. Our results provide new information on the nature of this defect,and show that an increase of the aluminum content allows the Cr concentrationto be maintained in the range of values required to maintain thepassivity of the steel, thus improving the surface quality.