TY - JOUR
T1 - Improving mechanical properties of pinless friction stir spot welded joints by eliminating hook defect
AU - Li, Wenya
AU - Li, Jinfeng
AU - Zhang, Zhihan
AU - Gao, Dalu
AU - Wang, Weibing
AU - Dong, Chunlin
PY - 2014/10
Y1 - 2014/10
N2 - Hook defect (HD) seriously decreases the mechanical properties of friction stir spot welded (FSSW) joints. In this study, two methods were therefore used to eliminate the HD in pinless FSSW joints. The one is changing welding parameters such as rotating speed and dwell time. The other one is FSSW plus subsequent friction stir welding (FSSW-FSW), which is an innovative method proposed in this study. Experimental results showed that the HD in pinless FSSWed AA2024 joints was successfully eliminated by using FSSW-FSW, not by changing process parameters. The joints without HD exhibited a tensile-shear load of as much as 12. kN, which was higher than that of 6.9. kN in the joints with HD. Furthermore, it was proved that the tensile-shear load is not greatly improved only by increasing the nugget zone when HD still existed in the FSSW joints. In addition, the fracture morphology analysis demonstrated that the shear fracture of the FSSW-FSW joints took place along the boundary between the upper and lower sheets through the weld nugget, and the faying surface between the two sheets was completely sheared off.
AB - Hook defect (HD) seriously decreases the mechanical properties of friction stir spot welded (FSSW) joints. In this study, two methods were therefore used to eliminate the HD in pinless FSSW joints. The one is changing welding parameters such as rotating speed and dwell time. The other one is FSSW plus subsequent friction stir welding (FSSW-FSW), which is an innovative method proposed in this study. Experimental results showed that the HD in pinless FSSWed AA2024 joints was successfully eliminated by using FSSW-FSW, not by changing process parameters. The joints without HD exhibited a tensile-shear load of as much as 12. kN, which was higher than that of 6.9. kN in the joints with HD. Furthermore, it was proved that the tensile-shear load is not greatly improved only by increasing the nugget zone when HD still existed in the FSSW joints. In addition, the fracture morphology analysis demonstrated that the shear fracture of the FSSW-FSW joints took place along the boundary between the upper and lower sheets through the weld nugget, and the faying surface between the two sheets was completely sheared off.
KW - 2024-T3 aluminum alloy
KW - Fracture morphology
KW - Friction stir spot welding
KW - Hook defect
KW - Tensile-shear load
UR - http://www.scopus.com/inward/record.url?scp=84902206983&partnerID=8YFLogxK
U2 - 10.1016/j.matdes.2014.05.028
DO - 10.1016/j.matdes.2014.05.028
M3 - 文章
AN - SCOPUS:84902206983
SN - 0264-1275
VL - 62
SP - 247
EP - 254
JO - Materials and Design
JF - Materials and Design
ER -