Mechanical property and characterization of 7A04-T6 aluminum alloys bonded by friction stir welding. (April 2020)

• Record Type: Journal Article
• Authors: Li, Jianing; Su, Molin; Qi, Wenjun; Wang, Chen; Zhao, Peng; Ni, Fei; Liu, Kegao
• Is Part Of: Journal of manufacturing processes. Volume 52(2020)
• Page Start: 263
• Page End: 269
• Publication Date: 2020-04
• Subjects: Friction stir welding -- Aluminum alloys -- Tensile strength -- Fatigue limit; Production management -- Data processing -- Periodicals; Manufacturing processes -- Periodicals; Procestechnologie; Productietechniek; Production -- Gestion -- Informatique -- Périodiques; Fabrication -- Périodiques; Manufacturing processes; Production management -- Data processing; Periodicals; 670.5
• DOI: 10.1016/j.jmapro.2020.02.018
• Languages: English
• ISSNs: 1526-6125

Abstract

Highlights: 7A04 aluminum alloy FSW joint with excellent mechanical properties was fabricated. The tensile strength of the FSW joint was 452 MPa, which was 77.93 % of the base material. According to the up-and-down test method, the fatigue limit of the FSW joint was 141 MPA. When N (cycle) < 10 5 in S-N curve, the fatigue strength decreased with the increase of fatigue life. Abstract: The 7A04-T6 aluminum (Al) alloys were bonded via a friction stir welding (FSW) technique. The tensile strength of this FSW joint was the highest when the welding speed was 120 mm/min and the rotation speed was 1000 r/min, which reached 77.93 % of that of the base material (BM). The nugget zone (NZ) consisted mainly of the fine grains; the grain boundary misorientation angle in NZ was about 15°, indicating that the propagation of micro-crack was hindered to a certain degree, improving the toughness of this joint. The S-N curve of this joint showed that the fatigue strength decreased with an enhancement of the fatigue life when N was below 10 5, also N was above 10 6 . The fatigue limit (141 MPa) of the joint was calculated through an up-and-down test method, the fatigue fracture position occurred in HAZ, exhibiting the ductile fracture. Then a laser local heat treatment (LLHT) process was carried out on this weld seam, which refined the microstructure, strengthening the mechanical property of this FSW joint.