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The Microstructure and Mechanical Properties of 5083, 6005A and 7N01 Aluminum Alloy Gas Metal Arc-Welded Joints for High-Speed Train: A Comparative Study. METALS 2022. [DOI: 10.3390/met12020213] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
This study aimed to conduct a comparative study on the microstructure and mechanical performance of 5083, 6005A and 7N01 Al joints used in China Railway High-speed (CRH) trains. We connected 10 mm-thick plates by three-layer and three-pass gas metal arc welding (GMAW). The results indicated that 6005A and 7N01 Al joints were more sensitive to grain boundary liquation in the partially melted zone (PMZ) than 5083 Al joins. Besides, recrystallization was obtained in heat-affected zones (HAZ). The 5083 Al joints experienced the most severe recrystallization and the grain size changed from 6.32 (BM) to 32.44 (HAZ) μm duo to intracrystalline strain induced by cold-rolled processes. The 7N01 Al alloys experienced the lowest extent of recrystallization and the grain size increased from 5.32 (BM) to 22.31 (HAZ) μm. Furthermore, significant precipitate evolution in the HAZ was observed. Original thin β” precipitates dissolved in HAZ of 6005A Al joints and transformed to the softer β phase. However, less precipitation transition was examined in 5083 and 7N01 Al joints. The precipitates’ evolution produced a softening region in HAZ of 6005A joints where the hardness was only 55 HV. The microhardness profile of the other two Al joints was less affected. The tensile strength of 5083, 6005A, and 7N01 Al alloy joints reached 323, 206 and 361 MPa, respectively. The 5083 Al and 6005A Al joints failed at HAZ near the fusion line while 7N01 Al joints failed at the fusion zone owing to the high strength of the base metal. The liquation, coarse grains by recrystallization, and precipitate evolution all decreased local strength, resulting in the fracture at HAZ.
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Ma J, Sun J, Guan Q, Yang Q, Tang J, Zou C, Wang J, Tang B, Kou H, Wang H, Gao J, Li J, Wang WY. The Localized Corrosion and Stress Corrosion Cracking of a 6005A-T6 Extrusion Profile. MATERIALS 2021; 14:ma14174924. [PMID: 34501014 PMCID: PMC8434543 DOI: 10.3390/ma14174924] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 08/21/2021] [Accepted: 08/23/2021] [Indexed: 11/16/2022]
Abstract
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.
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Affiliation(s)
- Jijun Ma
- CRRC Tangshan Co., Ltd., Tangshan 063035, China; (J.S.); (Q.G.); (H.W.); (J.G.)
- Correspondence: (J.M.); (J.L.); (W.Y.W.)
| | - Jing Sun
- CRRC Tangshan Co., Ltd., Tangshan 063035, China; (J.S.); (Q.G.); (H.W.); (J.G.)
| | - Quanmei Guan
- CRRC Tangshan Co., Ltd., Tangshan 063035, China; (J.S.); (Q.G.); (H.W.); (J.G.)
| | - Qingwei Yang
- State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China; (Q.Y.); (J.T.); (C.Z.); (J.W.); (B.T.); (H.K.)
| | - Jian Tang
- State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China; (Q.Y.); (J.T.); (C.Z.); (J.W.); (B.T.); (H.K.)
| | - Chengxiong Zou
- State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China; (Q.Y.); (J.T.); (C.Z.); (J.W.); (B.T.); (H.K.)
| | - Jun Wang
- State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China; (Q.Y.); (J.T.); (C.Z.); (J.W.); (B.T.); (H.K.)
- Innovation Center, NPU Chongqing, Chongqing 401135, China
| | - Bin Tang
- State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China; (Q.Y.); (J.T.); (C.Z.); (J.W.); (B.T.); (H.K.)
- Innovation Center, NPU Chongqing, Chongqing 401135, China
| | - Hongchao Kou
- State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China; (Q.Y.); (J.T.); (C.Z.); (J.W.); (B.T.); (H.K.)
- Innovation Center, NPU Chongqing, Chongqing 401135, China
| | - Haisheng Wang
- CRRC Tangshan Co., Ltd., Tangshan 063035, China; (J.S.); (Q.G.); (H.W.); (J.G.)
| | - Jun Gao
- CRRC Tangshan Co., Ltd., Tangshan 063035, China; (J.S.); (Q.G.); (H.W.); (J.G.)
| | - Jinshan Li
- State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China; (Q.Y.); (J.T.); (C.Z.); (J.W.); (B.T.); (H.K.)
- Innovation Center, NPU Chongqing, Chongqing 401135, China
- Correspondence: (J.M.); (J.L.); (W.Y.W.)
| | - William Yi Wang
- State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi’an 710072, China; (Q.Y.); (J.T.); (C.Z.); (J.W.); (B.T.); (H.K.)
- Innovation Center, NPU Chongqing, Chongqing 401135, China
- Correspondence: (J.M.); (J.L.); (W.Y.W.)
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