摘要
通过动电位极化曲线和微观腐蚀路径分析,研究了不同均匀化处理条件下和工艺状态下的6082铝合金电化学腐蚀行为,并且探讨了其腐蚀机理。结果表明,随着6082铝合金均匀化温度升高或时间延长,其电化学腐蚀后的腐蚀产物Al(OH)_3逐渐增多、增厚,腐蚀电流密度逐渐减小,合金的耐腐蚀性能增强;对于T6态锻造和T1态挤压的合金,由于锻造流线和挤压流线的组织形态差异,使腐蚀产物Al(OH)_3的分布位置不同,从而使锻造合金的腐蚀电流密度比挤压合金的要小,耐腐蚀性能更好;合金塑性变形流线中分布有颗粒状Si晶体和AlMnFeSi第二相颗粒。当腐蚀溶液与第二相Si粒子接触时,首先在Si粒子与基体之间的界面产生腐蚀,形成腐蚀裂纹。当腐蚀逐步扩展至晶界或亚晶界处时,由于晶界上连续分布的β?-Mg_2Si析出相与晶界无沉淀析出带(PFZ)构成连续的微型原电池,从而形成网状晶间腐蚀。
The inter-granular corrosion behavior and the relevant corrosion mechanism of 6082 Al-alloys subjected to different homogenization treatments were investigated. Results show that, with the rising temperature and/or time of the homogenization process, the corrosion product Al（OH）3 increases,and thus the scale thickens gradually while the corrosion current density decreases, which implies the enhancement of the corrosion resistance of the alloy. In addition, the corrosion current density of the forged alloy is much smaller than that of the extruded one, accordingly its corrosion resistant performance is better. There are two kinds of second phase particles, Si-and AlMnFeSi-phase, homogeneously distributed within the plastic deformation streamline of the alloy. When the alloy with second particles of Si-phase was immersed in a corrosive solution, the matrix around particles dissolved preferentially and corrosion cracks form as the matrix serves as anode and Si particles serve as cathode, i.e. they form micro-galvanic cells. Meanwhile, corrosion cracks develop into networks due to the existence of electro-chemical corrosive coupling between β^--Mg2Si and PFZ along the grain boundaries.
作者
单际强
侯丹丹
张今捷
辛秀成
曹国华
黄根哲
SHAN Jiqiang;HOU Dandan;ZHANG Jinjie;XIN Xiucheng;CAO Guohua;HUANG Genzhe(School of Electro-mechanical Engineering,Changchun University of Science and Technology,Changchun 130022,China)
出处
《腐蚀科学与防护技术》
CAS
CSCD
北大核心
2018年第4期353-361,共9页
Corrosion Science and Protection Technology
关键词
材料失效
晶间腐蚀
电化学测试
极化曲线
均匀化处理
materials failure
inter-granular corrosion
electrochemical testing
polarization curve,homogenization treatment
