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A study on microstructure evolution and corrosion resistance of cutting layer metal of 7055 aluminum alloy based on extreme environment
Author(s) -
Zhang Ping,
Wang Youqiang,
Li Weihui,
Wang Qing,
Li Yuanyuan
Publication year - 2018
Publication title -
materials and corrosion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.487
H-Index - 55
eISSN - 1521-4176
pISSN - 0947-5117
DOI - 10.1002/maco.201709957
Subject(s) - materials science , microstructure , metallurgy , alloy , recrystallization (geology) , dynamic recrystallization , aluminium , grain size , corrosion , strain rate , composite material , hot working , paleontology , biology
In order to evaluate the mechanism of microstructure evolution and corrosion resistance of 7055 aluminum alloy in extreme environment, 7055 aluminum alloy which was subjected to T6I4 heat treatment was selected as the research object. High speed machining experiments were performed at low temperature (−60 °C) and high temperature (350 °C). The experimental results show that the dislocation density at low temperature is higher than that at high temperature under the same cutting speed and feed rate, and the grain size at low temperature is higher than that at high temperature too. Under the high temperature environment, with the increasing cutting speed, the degree of fibrouse texture of the grains is weakened and the dynamic recrystallization is obviously enhanced. With the increase of the feed rate, the microstructure is elongated and deformed in the direction of deformation after low temperature cutting, also, incomplete recrystallization occurs in 7055. The larger the feed amount is, the finer and longer the fibrouse grains of the metallographic structure of cutting layer metal of 7055 aluminum alloy.The higher the cutting speed, the smaller the dislocation density. No dislocations were found in the microstructure of the 7055 aluminum alloy cutting layer in the high temperature environment but at higher cutting speed the number of precipitated phase is reduced and the GP‐zones and η'‐phases are transformed into η‐phases. In the high temperature environment, the weight percentage of Al element in Al(OH) 3 decreases by 45%, the weight percentage of O element decreases by 16%, In the high temperature environment, there is a small amount of Cl elements in the corrosion products of the cutting layer metal after cutting, Cl elements are relatively low in weight percent, Cl − is mainly to destroy the oxide film When the corrosion occurs, also, Cl − and Al 3+ form a water‐soluble compound.