晶粒度对LY12铝合金应力腐蚀断裂行为的影响  

Effect of Grain Size on Stress Corrosion Cracking Behavior of LY12 Alloy

作　　者：孙忠志[1] 王瑞阳[2] 于美[2] 李松梅[2] 王宗武[2] 刘建华[2] 

机构地区：[1]沈阳飞机设计研究所,辽宁沈阳110035 [2]北京航空航天大学材料科学与工程学院,北京100191

出　　处：《中国材料进展》2013年第3期179-184,共6页Materials China

摘　　要：以恒载荷应力腐蚀拉伸实验,研究了具有粗晶层的LY12铝合金在3.5%NaCl+0.5%H2O2溶液中的应力腐蚀行为。采用交流阻抗技术(EIS)分别对具有粗晶层和去除粗晶层后的LY12铝合金试样进行了电化学测试,利用扫描电镜(SEM)和三维立体显微镜,系统观察分析了合金试样的显微组织和应力腐蚀断口形貌,分别计算了该合金试样表层粗晶区和内层细晶区各自的晶粒度。结果表明,LY12铝合金表层粗晶区的晶粒度等级为5.88,内层细晶区的晶粒度等级为12.71;粗晶区晶粒尺寸较大,对合金起到一定的保护作用,能够显著降低其应力腐蚀敏感性;带有粗晶层的LY12铝合金试样交流阻抗谱阻抗半径为2 500Ω,去除粗晶层后,试样的阻抗半径下降至2 000Ω。具有粗晶层的LY12铝合金在3.5%NaCl+0.5%H2O2溶液环境中耐应力腐蚀性能更强。The stress corrosion cracking（SCC） behavior of LY12 alloy with coarse-grained layer was investigated in 3.5 % NaCl＋ 0. 5 % H2O2 solution by constant load stress corrosion test. Electrochemical impedance spectroscopy （EIS） of the LYI2 alloy with and without coarse-grained layer was studied. The microstructure and fracture morphology were observed and analyzed by 3D-cubic microscope and scanning electron microscope （SEM）. The grain size of surface layer coarse-grain zone and the inner layer fine zone of this alloy were calculated too. The results show that the grain size of coarse grain grade is 5.88, while that of inner zone is 1：2.71. Because grain size of coarse-grain layer is bigger than the inner zone, the big size grains can protect the LY12 alloy from stress corrosion cracking and remarkably decrease the susceptibility of alloy from SCC in 3.5 % NaCl ＋ 0.5 % H2O2 solution. The impedance of the alloy with coarse-grain layer is 2 500 Ω; after removing the coarse-grain layer, the impedance declines to 2 000 Ω. Consequently, coarse-grained LY12 alloy has a better SCC resistance in 3.5 % NaCl ＋0.5 % H2O2 solution.

关 键 词：LY12铝合金 粗晶层 应力腐蚀 

分 类 号：TG172[金属学及工艺—金属表面处理]