Abstract

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

Author(s):: SUN Zhongzhi; WANG Ruiyang; YU Mei; LI Songmei; WANG Zongwu; LIU Jianhua; (1.Shenyang Aircraft Design & Research Institute, Shenyang 110035, China)
(2.School of Materials Science and Engineering, Beihang University, Beijing 100083, China)

Abstract:: The stress corrosion cracking(SCC) behavior of LY12 alloy with coarse grained layer was investigated in 3 5 % NaCl+05 % H2O2 solution by constant load stress corrosion test Electrochemical impedance spectroscopy (EIS) of the LY12 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 12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 %H2O2 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.