四种典型大气环境下7B50铝合金的腐蚀行为研究

Corrosion Behavior of 7B50 Aluminum Alloy in Four Typical Atmospheric Environments

目的研究湿热海洋、干热沙漠、寒冷乡村、暖温高原四种典型大气环境对7B50铝合金腐蚀行为的影响。方法采用户外大气自然环境暴露试验,通过宏观腐蚀形貌分析、金相显微形貌分析、腐蚀深度分析和拉伸性能分析,对比研究7B50-T7751和7B50-T77511两种铝合金在不同大气环境中的腐蚀行为和规律。结果暴露试验周期为3 a时,7B50-T7751铝合金在湿热海洋大气环境中腐蚀严重,局部最大腐蚀深度为166μm,抗拉强度和断后伸长率分别下降了5%和25%;在干热沙漠大气环境下腐蚀较重,局部最大腐蚀深度为44μm;在寒冷乡村、暖温高原大气环境下未见明显腐蚀。7B50-T77511铝合金在四种典型大气环境下均表现出明显腐蚀,局部最大腐蚀深度分别为141、80、42、29μm。结论两种7B50铝合金在典型大气环境中表现出不同的耐蚀性,在微观上均表现为点蚀和晶间腐蚀的混合腐蚀,具有明显的晶间腐蚀和剥蚀倾向。两种铝合金暴露在相同大气环境中时,7B50-T7751板材耐蚀性较7B50-T77511型材略好。

The paper aims to research the corrosion behavior of 7B50 aluminum alloy in four typical atmospheric environ-ments:damp hot ocean,dry-heat desert,cold countryside and warm plateau.The corrosion behaviors and rules of 7B50-T7751 and 7B50-T77511 aluminum alloys in different atmospheric environments were investigated and compared by test the macro-scopic corrosion morphology,the metallographic microscope,the corrosion depth and the tensile strength of the material.After exposed for 3 years,the corrosion of 7B50-T7751 aluminum alloy was serious in damp hot ocean atmospheric environment,the local maximum corrosion depth was 166μm,the tensile strength and elongation after fracture decreased by 5%and 25%,re-spectively.And the corrosion was secend in dry-heat desert atmospheric environment,the local maximum corrosion depth was 44μm.And no obvious corrosion was found in cold countryside and warm plateau atmosphere environment.However,when exposed to the damp hot ocean,dry-heat desert,cold countryside and warm plateau atmospheric environment,the 7B50-T77511 aluminum alloy showed obvious corrosion.The local maximum corrosion depths were 141,80,42 and 29μm,respectively.The corrosion resistance of 7B50 aluminum alloy in typical atmospheric environment is different,it mainly presents the mixed cor-rosion of pitting corrosion and intergranular corrosion,and it has obvious tendency of intergranular corrosion and denudation.And the corrosion resistance of 7B50-T7751 plate is slightly better than that of 7B50-T77511 profile when exposed to the same atmospheric environment.