scholarly journals Microstructural Characteristics and Mechanical Properties of Friction Stir Spot Welded 2A12-T4 Aluminum Alloy

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Huijie Liu ◽  
Yunqiang Zhao ◽  
Xingye Su ◽  
Lilong Yu ◽  
Juncai Hou

2A12-T4 aluminum alloy was friction stir spot welded, and the microstructural characteristics and mechanical properties of the joints were investigated. A softened microstructural region existed in the joint, and it consisted of stir zone (SZ), thermal mechanically affected zone (TMAZ), and heat affected zone (HAZ). The minimum hardness was located in TMAZ, and the average hardness value in SZ can be improved by appropriately increasing welding heat input. The area of complete bonding region at the interface increased with increasing welding heat input because more interface metals were mixed. In a certain range of FSSW parameters, the tensile shear failure load of the joint increased with increasing rotation speed, but it decreased with increasing plunge rate or decreasing shoulder plunging depth. Two kinds of failure modes, that is, shear fracture mode and tensile-shear mixed fracture mode, can be observed in the tensile shear tests, and the joint that failed in the tensile-shear mixed fracture mode possessed a high carrying capability.

2018 ◽  
Vol 206 ◽  
pp. 03002 ◽  
Author(s):  
Yunqiang Zhao ◽  
Chungui Wang ◽  
Chunlin Dong

In this study, a novel welding method called water cooling bobbin-tool friction stir welding (WBT-FSW) was developed. 4 mm-thick 6063-T6 aluminum alloy sheets were successfully jointed by WBT-FSW. Comparative studies on macro/microstructural characteristics and mechanical properties of the WBT-FSW and conventional bobbin-tool friction stir welding (BT-FSW) joints were carried out. The results indicated that the water mist cooling can significantly decrease the welding temperature and improve both the weld formation and the mechanical properties of the joint. The tensile strength of the WBT-FSW joint was 11.4% higher than that of BT-FSW joint.


2016 ◽  
Vol 48 (1) ◽  
pp. 208-229 ◽  
Author(s):  
Murshid Imam ◽  
Yufeng Sun ◽  
Hidetoshi Fujii ◽  
Ninshu Ma ◽  
Seiichiro Tsutsumi ◽  
...  

2021 ◽  
Author(s):  
Peng Zhang ◽  
Shengdun Zhao ◽  
Chuanwei Zhang ◽  
Zheng Chen ◽  
Jiaying Zhang ◽  
...  

Abstract Aluminum alloy and steel composite structures are increasingly and widely used in the automotive industry and other fields owing to their advantages of light weight and high comprehensive performance. The high-quality joining of aluminum alloy and steel has become the research focus in China and overseas. The current study proposes a probeless friction stir extrusion joining (P-FSEJ) process to avoid intermetallic compounds, reduce wear of tools, and obtain a spot joint without keyhole defects. Strong mechanical interlock is formed after that the plasticized aluminum alloy (AA) 6061-T6 is extruded into the prefabricated threaded hole of a Q235 steel plate in the P-FSEJ process. Three distinct zones in the typical symmetrical “basin-shaped” P-FSEJed joint are observed. In addition to the rotation speed, the diameter of the threaded hole is also specifically used to study the influence on the mechanical properties of the joint. When the rotation speed is 1200 rpm, the maximum tensile-shear loads of the M6 and M7 threaded hole joints are 2882.93 N and 3344.74 N, respectively, while the M8 threaded hole joint is 4139.58 N at rotation speed of 1000 rpm. Two typical fracture failure modes of the P-FSEJed joints, namely, rivet shear and rivet pullout-shear fractures, are obtained under tensile-shear loading. Lastly, the P-FSEJed joints with mode “P” fracture failure generally have high strength and energy absorption capability.


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