Computer Simulation of Surface Cracks Behavior in Anhydrous Chemical Conversion Coatings on Magnesium Alloy

Abstract

In the conversion coatings, some uniformly distributed micro surface cracks always occur but the surface cracks behavior is rarely studied due to the frequent initiation in the real test conditions. In this work, computer simulation of micro surface cracks behavior and internal stresses generated in the anhydrous chemical conversion coating was carried out using the finite element method with the help of ABAQUS software. The Mises stress distribution, S 11 stress variation, and the stress-time curves were obtained. The results show that the internal stresses generated in the conversion coating increase obviously with increasing time, and the stresses at the center and boundary of coating pieces are bigger than the ones in other areas while the S 11 stresses around the center are bigger than the ones near the boundary. The cracks at the interface of coating pieces develop gradually and are as V-type cracks finally. The width of crack mouth opened is different since the contraction degree of each coating piece is different.