Through-thickness inhomogeneity of localized corrosion in 7050-T7451 Al alloy thick plate  

作　　者：丰雷 潘清林 韦莉莉 黄志其 刘志铭 

机构地区：[1]School of Materials Science and Engineering Central South University [2]Guangdong Fenglu Aluminium Co.Ltd.

出　　处：《Journal of Central South University》2015年第7期2423-2434,共12页中南大学学报（英文版）

基　　金：Project(2012CB619503)supported by the National Basic Research Program of China;Project(2013AH100055)supported by the Foshan Civic Technological Innovation Foundation,China

摘　　要：The through-thickness corrosion inhomogeneity of 7050-T7451 Al alloy thick plate was studied using immersion tests, potentiodynamic polarization, electrochemical impedance spectroscopy(EIS), slow strain rate testing(SSRT) technique combined with optical microscopy(OM), scanning electron microscopy(SEM) and transmission electron microscopy(TEM). The results show that the through-thickness corrosion resistance is ranked in the order of T/2>surface>T/4. And the 75 mm-thick 7050 alloy plate presents better corrosion resistance than the 35 mm-thick plate. The results are discussed in terms of the combined effect of recrystallization and cooling rate in quenching. Alloy with lower volume fraction of recrystallization and smaller grain aspect ratio displays better corrosion resistance. The lower corrosion resistance caused by the slower cooling rate results from the higher coverage rate of grain boundary precipitates and larger width of precipitate free zone.The through-thickness corrosion inhomogeneity of 7050-T7451 Al alloy thick plate was studied using immersion tests, potentiodynamic polarization, electrochemical impedance spectroscopy（EIS）, slow strain rate testing（SSRT） technique combined with optical microscopy（OM）, scanning electron microscopy（SEM） and transmission electron microscopy（TEM）. The results show that the through-thickness corrosion resistance is ranked in the order of T/2〉surface〉T/4. And the 75 mm-thick 7050 alloy plate presents better corrosion resistance than the 35 mm-thick plate. The results are discussed in terms of the combined effect of recrystallization and cooling rate in quenching. Alloy with lower volume fraction of recrystallization and smaller grain aspect ratio displays better corrosion resistance. The lower corrosion resistance caused by the slower cooling rate results from the higher coverage rate of grain boundary precipitates and larger width of precipitate free zone.

关 键 词：aluminium polarization electrochemical impedance spectroscopy（EIS） intergranular corrosion exfoliation corrosion stress corrosion 

分 类 号：TG146.21[一般工业技术—材料科学与工程] TG171[金属学及工艺—金属材料]