Constitutive relations of micro-arc oxidation coated aluminum alloy

The stress and displacement of the coating and substrate were analyzed according to the constructive relations of the micro-arc oxidation (MAO) coated aluminum alloy. Effect of the yielding of the interlayer and substrate on the constructive relations was explored. This study revealed the changes in displacement relationship between the coating and substrate under high and low tensile stresses. The yielding of the interlayer resulted in the displacement of the coating to be lower than that of the substrate. The results provided a theoretical basis for the residual stress relaxation, the larger plastic deformation zone found in the substrate adjacent to the MAO coating, and the disappearance of pores and the closure of cracks on the coating surface. The strain of the coating surface was measured using the YE2539 high-speed strain gauge and BX120-5AA strain gauge. The theoretical stress of the coating surface was compared with the measured results, exhibiting good consistency. Furthermore, the results of the in-situ observation test in previous study verified the rationality of the theoretical model analysis. In addition, the effect of the residual stress on the mechanical properties of the MAO coated samples was discussed. The residual compressive stress in MAO coating was beneficial to the improvement of the mechanical properties. •The yielding of the interlayer decreased the coating displacement.•The yielding of the interlayer significantly affected the displacement and stress fields.•Residual stress affected the mechanical properties of the coated samples.•Defects in MAO coatings impaired the mechanical properties.