Stress-corrosion behavior and characteristics of the friction stir welding of an AA2198-T34 alloy

• Published in: International journal of minerals, metallurgy and materials Vol. 27; no. 6; pp. 774 - 782
• Main Authors: Zeng, Quan-qing, Zeng, Song-sheng, Wang, Dong-yao
• Format: Journal Article
• Language: English
• Published: Beijing University of Science and Technology Beijing 01.06.2020; Springer Nature B.V; Research Institute of Light Alloy, Central South University, Changsha 410083, China; Key Laboratory of the Ministry of Education of Nonferrous Metals, Central South University, Changsha 410083, China%Research Institute of Light Alloy, Central South University, Changsha 410083, China; Technology Center, Valin ArcelorMittal Automotive Steel Co., Ltd., Loudi 417009, China
• Subjects: Aluminum; Aluminum base alloys; Ceramics; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composites; Compressive properties; Corrosion; Corrosion and Coatings; Corrosion effects; Corrosion potential; Crack initiation; Dislocation density; Friction; Friction stir welding; Glass; Grain boundaries; Heat affected zone; Materials Science; Metallic Materials; Microcracks; Natural Materials; Precipitates; Residual stress; Strain rate; Stress corrosion; Stress corrosion cracking; Surfaces and Interfaces; Tensile stress; Thin Films; Tribology; Welding; residual stress; AA2198-T34 alloy; slow strain rate test; grain boundary characteristic; friction stir welding
• ISSN: 1674-4799; 1869-103X
• DOI: 10.1007/s12613-019-1924-4

To better understand the stress-corrosion behavior of friction stir welding (FSW), the effects of the microstructure on the stress-corrosion behavior of the FSW in a 2198-T34 aluminum alloy were investigated. The experimental results show that the low-angle grain boundary (LABs) of the stir zone (SZ) of FSW is significantly less than that of heated affected zone (HAZ), thermo-mechanically affected zone (TMAZ), and parent materials (PM), but the grain boundary precipitates (GBPs) T1 (Al 2 CuLi) were less, which has a slight effect on the stress corrosion. The dislocation density in SZ was greater than that in other regions. The residual stress in SZ was +67 MPa, which is greater than that in the TMAZ. The residual stress in the HAZ and PM is −8 MPa and −32 MPa, respectively, and both compressive stresses. The corrosion potential in SZ is obviously less than that in other regions. However, micro-cracks were formed in the SZ at low strain rate, which indicates that the grain boundary characters and GBPs have no significant effect on the crack initiation in the stress-corrosion process of the AA2198-T34. Nevertheless, the residual tensile stress has significant effect on the crack initiation during the stress-corrosion process.