The Localized Corrosion and Stress Corrosion Cracking of a 6005A-T6 Extrusion Profile
Jijun Ma,
Jing Sun,
Quanmei Guan,
Qingwei Yang,
Jian Tang,
Chengxiong Zou,
Jun Wang,
Bin Tang,
Hongchao Kou,
Haisheng Wang,
Jun Gao,
Jinshan Li,
William Yi Wang
Affiliations
Jijun Ma
CRRC Tangshan Co., Ltd., Tangshan 063035, China
Jing Sun
CRRC Tangshan Co., Ltd., Tangshan 063035, China
Quanmei Guan
CRRC Tangshan Co., Ltd., Tangshan 063035, China
Qingwei Yang
State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Jian Tang
State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Chengxiong Zou
State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Jun Wang
State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Bin Tang
State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Hongchao Kou
State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
Haisheng Wang
CRRC Tangshan Co., Ltd., Tangshan 063035, China
Jun Gao
CRRC Tangshan Co., Ltd., Tangshan 063035, China
Jinshan Li
State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
William Yi Wang
State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China
In the present work, the localized corrosion and stress corrosion cracking (SCC) behaviors of a commercial 6005A-T6 aluminum extrusion profile was studied comprehensively. The velocity of crack growth in self-stressed double-cantilever beam (DCB) specimens under constant displacement was estimated, which also provides insight into the local microstructure evolutions at the crack tips caused by the localized pitting corrosion, intergranular corrosion (IGC), and intergranular SCC. Characterizations of local corrosion along the cracking path for a period of exposure to 3.5% NaCl were revealed via optical microscope (OM), scanning electron microscope (SEM), and electron backscatter diffraction (EBSD). The typical features of the pits dominated by the distribution of precipitates included the peripheral dissolution of the Al matrix, channeling corrosion, intergranular attack, and large pits in the grains. The discontinuous cracking at the crack tips indicated the hydrogen-embrittlement-mediated mechanism. Moreover, the local regions enriched with Mg2Si and Mg5Si6 phases and with low-angle grain boundaries presented better SCC resistance than those of the matrix with high-angle grain boundaries, supporting a strategy to develop advanced Al–Mg–Si alloys via interfacial engineering.