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Title: Friction stir welding joint of dissimilar materials between AZ31B magnesium and 6061 aluminum alloys: Microstructure studies and mechanical characterizations

Friction stir welding is an efficient manufacturing method for joining dissimilar alloys, which can dramatically reduce grain sizes and offer high mechanical joint efficiency. Lap FSW joints between dissimilar AZ31B and Al 6061 alloy sheets were made at various tool rotation and travel speeds. Rotation and travel speeds varied between 560–1400 r/min and 16–40 mm/min respectively, where the ratio between these parameters was such that nearly constant pitch distances were applied during welding. X-ray diffraction pattern (XRD), optical microscopy images (OM), electron probe microanalysis (EPMA) and scanning electron microscopy equipped with an energy-dispersive X-ray spectroscopy (SEM-EDS) were used to investigate the microstructures of the joints welded. Intermetallic phases including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β) were detected in the weld zone (WZ). For different tool rotation speeds, the morphology of the microstructure in the stir zone changed significantly with travel speed. Lap shear tensile test results indicated that by simultaneously increasing the tool rotation and travel speeds to 1400 r/min and 40 mm/min, the joint tensile strength and ductility reached a maximum. Microhardness measurements and tensile stress–strain curves indicated that mechanical properties were affected by FSW parameters and mainly depended on the formation of intermetallic compounds inmore » the weld zone. In addition, a debonding failure mode in the Al/Mg dissimilar weld nugget was investigated by SEM and surface fracture studies indicated that the presence of intermetallic compounds in the weld zone controlled the failure mode. XRD analysis of the fracture surface indicated the presence of brittle intermetallic compounds including Al{sub 12}Mg{sub 17} (γ) and Al{sub 3}Mg{sub 2} (β). - Highlights: • Dissimilar Al/Mg joint was obtained by lap friction stir welding technique. • Effect of rotation and travel speeds on the formation of intermetallic compounds • Microstructure and chemical studies including metallography, XRD, SEM-EDS, and EPMA • Mechanical property tests such as stress–strain curves, failure load and hardness • IMCs as Al{sub 3}Mg{sub 2} and Al{sub 12}Mg{sub 17} were identified in weld nugget and at Al/Mg interface.« less
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [5] ;  [6]
  1. Department of Materials Science and Engineering, Science and Research Branch, Islamic Azad University, Tehran 141554933 (Iran, Islamic Republic of)
  2. Department of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta T6G 2V4 (Canada)
  3. Young Researchers and Elites Club, Tehran North Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of)
  4. Faculty of Materials Engineering, Sahand University of Technology, Tabriz 513351996 (Iran, Islamic Republic of)
  5. Department of Materials Science and Engineering, Sharif University of Technology, Tehran 113659466 (Iran, Islamic Republic of)
  6. Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)
Publication Date:
OSTI Identifier:
22476064
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Characterization; Journal Volume: 101; Other Information: Copyright (c) 2015 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALUMINIUM ALLOYS; DUCTILITY; ELECTRON MICROPROBE ANALYSIS; FRICTION; GRAIN SIZE; INTERFACES; INTERMETALLIC COMPOUNDS; MAGNESIUM ALLOYS; METALLOGRAPHY; MICROHARDNESS; OPTICAL MICROSCOPY; ROTATION; SCANNING ELECTRON MICROSCOPY; STRAINS; STRESSES; SURFACES; WELDED JOINTS; WELDING; X-RAY DIFFRACTION; X-RAY SPECTROSCOPY