基于7A04-T6铝合金的硫酸阳极氧化膜性能失效与控制策略分析OA

This paper conducts a failure analysis on the phenomenon where,after sulfuric acid anodizing and black dyeing of the rear cover made of 7A04-T6 high-strength aluminum alloy in the aviation field,scattered to dense white spots appear on the surface during storage or thermal cycling impact,accompanied by the rubbing off of black particles.The root cause of the film failure is analyzed to be the residual inherent stress or processing stress inside the parts.7A04-T6 material has high hardness and strength but is extremely sensitive to stress concentration.These internal stresses are released during the oxidation process or subsequent environmental temperature changes,causing micro-deformation of the substrate,leading to cracking or local peeling of the porous anodizing film(mainly composed of Al2O3)with hard and brittle characteristics,thus manifesting as white spot defects.To solve this problem,this paper proposes a stress relief process of performing aging annealing treatment on the parts before oxidation(for 7A04-T6 material,it is recommended to use 175±5℃for 12～20 hours).Long-term practical verification shows that this pre-treatment measure can effectively stabilize the parts and significantly eliminate such defects,providing reliable key process guidance for surface treatment of critical components of high-strength aluminum alloys.