利用薄片穿透法确定铝合金最大蚀坑深度

目的研究铝合金最大蚀坑深度与环境试验时间的对应关系,为新型合金服役前的耐蚀性评级和结构件服役过程中的剩余寿命预测提供技术基础。方法利用光学显微镜、扫描电镜分析海洋大气环境中新型铝合金的腐蚀类型,并利用薄片穿透法研究铝合金薄片最大蚀坑深度与试验时间的对应关系。结果经过海洋大气环境暴露试验后,2A97铝合金发生了深入合金内部的严重点蚀,检测薄片试样背面电解液的出现时间,可以确定环境试验中蚀坑穿透薄片试样的时间。通过测量不同厚度薄片试样的穿透时间,可以确定最快生长局部腐蚀点的深度和时间的关系。结论中性盐雾试验环境下,达到相同的最大蚀坑深度,2A97铝合金与AA2024铝合金用时基本相当。

Determination of Maximum Pit Depth of Aluminium Alloy with Foil Penetration Technique

Objective To research the relationship between maximum corrosion pit depth in aluminium alloy and environmental testing time to provide technology foundation for corrosion resistance evaluation for new alloys prior to service and life prediction of structures during service. Methods The types of corrosion of a new aluminium alloy in marine atmosphere were analyzed with optical microscopy and SEM. The relationship between maximum corrosion pit depth in aluminium alloy foil and testing time was studied with the foil penetration technique. Results Severe pitting occurred and developed deep into the 2A97 aluminium alloy substrate after exposure in marine atmosphere. Time of foil penetration during environmental testing could be determined by examination the time of appearance of electrolyte from the back of the foil. After measurement of the penetration time of foils in various thicknesses, the relationship between the depth of the fastest growing corrosion pit and time could be determined. Conclusions In neutral salt fog testing environment, it generally takes the same time for 2A97 aluminium alloy and AA2024 aluminum alloy to reach the same maximum corrosion depth.