Fracture Analysis of AA6061-T6 Aluminum Alloy Spot Welding Lap Shear Model

2021 ◽  
Vol 10 (05) ◽  
pp. 509-518
Author(s):  
昊 李
Keyword(s):  
Aluminum Alloy ◽  
Spot Welding ◽  
Fracture Analysis ◽  
Shear Model ◽  
Lap Shear

scholarly journals Microstructure and mechanical properties of an ultrasonic spot welded aluminum alloy: the effect of welding energy

2021 ◽  
Author(s):  
He Peng ◽  
Daolun Chen ◽  
Xianquan Jiang
Keyword(s):  
Shear Strength ◽  
Aluminum Alloy ◽  
Cyclic Loading ◽  
Crack Growth ◽  
Failure Mode ◽  
Spot Welding ◽  
Energy Levels ◽  
Lap Shear Strength ◽  
Pull Out ◽  
Lap Shear

The aim of this study is to evaluate the microstructures, tensile lap shear strength, and fatigue resistance of 6022-T43 aluminum alloy joints welded via a solid-state welding technique–ultrasonic spot welding (USW)–at different energy levels. An ultra-fine necklace-like equiaxed grain structure is observed along the weld line due to the occurrence of dynamic crystallization, with smaller grain sizes at lower levels of welding energy. The tensile lap shear strength, failure energy, and critical stress intensity of the welded joints first increase, reach their maximum values, and then decrease with increasing welding energy. The tensile lap shear failure mode changes from interfacial fracture at lower energy levels, to nugget pull-out at intermediate optimal energy levels, and to transverse through-thickness (TTT) crack growth at higher energy levels. The fatigue life is longer for the joints welded at an energy of 1400 J than 2000 J at higher cyclic loading levels. The fatigue failure mode changes from nugget pull-out to TTT crack growth with decreasing cyclic loading for the joints welded at 1400 J, while TTT crack growth mode remains at all cyclic loading levels for the joints welded at 2000 J. Fatigue crack basically initiates from the nugget edge, and propagates with “river-flow” patterns and characteristic fatigue striations. Keywords: aluminum alloy; ultrasonic spot welding; EBSD; microstructure; tensile strength; fatigue

Electrically Assisted Friction Stir Spot Welding of Aluminum Alloy to Advanced High Strength Steel

2017 ◽  
Author(s):  
Kai Chen ◽  
Xun Liu ◽  
Jun Ni
Keyword(s):  
Aluminum Alloy ◽  
Material Flow ◽  
Spot Welding ◽  
Aluminum Matrix ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Steel Matrix ◽  
Friction Stir ◽  
Lap Shear ◽  
Electrically Assisted

This paper studies an electrically assisted friction stir spot welding (FSSW) process for joining aluminum alloy 6061-T6 to TRIP 780 steel. The electrical current shows to reduce the axial plunge force and assist the material flow of the aluminum matrix during the welding process. When electrical pulses and direct current (DC) with the same energy input are applied, the results show insignificant differences. Bulk material flow can be observed in the weld cross sections. A more uniform hook is generated at the Fe/Al interface after applying the current. Besides, the diffusion of aluminum atoms into the steel matrix is enhanced. Regarding the weld quality, electrically assisted FSSW improves the joint lap shear strength when compared with regular FSSW process.

Effects of Process Parameters on Friction Stir Spot Welding of Aluminum Alloy to Advanced High-Strength Steel

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Kai Chen ◽  
Xun Liu ◽  
Jun Ni
Keyword(s):  
Aluminum Alloy ◽  
Process Parameters ◽  
Cross Sections ◽  
Spot Welding ◽  
Dwell Time ◽  
Friction Stir Spot Welding ◽  
Thin Layers ◽  
Weld Strength ◽  
Friction Stir ◽  
Lap Shear

This paper studies a friction stir spot welding (FSSW) process that has been successfully applied to join aluminum alloy 6061-T6 to transformation-induced plasticity steel (TRIP) 780/800 steel. Cross sections of weld specimens show the formation of a hook with a swirling structure. A higher magnified scanning electron microscope (SEM) view of the swirling structure with energy dispersive X-ray spectroscopy (EDS) analysis reveals that it is composed of alternating thin layers of steel and Al–Fe intermetallic compounds (IMCs). To check the effect of different process parameters on the weld strength, the effects of tool plunge speed and dwell time were studied through the design of experiments (DOE) and analysis of variance (ANOVA) method. It shows that dwell time is a more dominant parameter in affecting the weld strength than plunge speed. Furthermore, investigation of failure using a lap shear tests reveals that cross nugget failure is the only failure mode. It also shows that cracks are initiated in the swirling structure at the tensile side of the weld nugget. After failure, a cleavage feature can be observed on the fractured surface.

scholarly journals Refill Friction Stir Spot Welding of Dissimilar 6061/7075 Aluminum Alloy

2019 ◽  
Vol 38 (2019) ◽  
pp. 69-75 ◽  
Author(s):  
Zhenlei Liu ◽  
Kang Yang ◽  
Dejun Yan
Keyword(s):  
Aluminum Alloy ◽  
Spot Welding ◽  
Joint Strength ◽  
Shear Failure ◽  
Failure Load ◽  
Friction Stir Spot Welding ◽  
Welding Parameters ◽  
Plunge Depth ◽  
Friction Stir ◽  
Lap Shear

AbstractRefill friction stir spot welding (RFSSW) was used to join 6061-T6 and 7075-T6 aluminum alloys in this work. Different sheet configurations and welding parameters were used to optimize joint strength. The effect of sleeve plunge depth on the microstructure and mechanical properties of the joints were investigated. The results showed that no defects were obtained when 6061-T6 aluminum alloy was placed as the upper sheet. The lap shear failure load of the joint using 6061-T6 aluminum alloy as the upper sheet was higher than that using 7075-T6 as the upper sheet. The maximum failure load of 12,892 N was attained when using the sleeve plunge depth of 3.6 mm. The joint failed at the upward flowing 7075 near the hook.

scholarly journals Microstructure and mechanical properties of an ultrasonic spot welded aluminum alloy: the effect of welding energy

2021 ◽  
Author(s):  
He Peng ◽  
Daolun Chen ◽  
Xianquan Jiang
Keyword(s):  
Shear Strength ◽  
Aluminum Alloy ◽  
Cyclic Loading ◽  
Crack Growth ◽  
Failure Mode ◽  
Spot Welding ◽  
Energy Levels ◽  
Lap Shear Strength ◽  
Pull Out ◽  
Lap Shear

The aim of this study is to evaluate the microstructures, tensile lap shear strength, and fatigue resistance of 6022-T43 aluminum alloy joints welded via a solid-state welding technique–ultrasonic spot welding (USW)–at different energy levels. An ultra-fine necklace-like equiaxed grain structure is observed along the weld line due to the occurrence of dynamic crystallization, with smaller grain sizes at lower levels of welding energy. The tensile lap shear strength, failure energy, and critical stress intensity of the welded joints first increase, reach their maximum values, and then decrease with increasing welding energy. The tensile lap shear failure mode changes from interfacial fracture at lower energy levels, to nugget pull-out at intermediate optimal energy levels, and to transverse through-thickness (TTT) crack growth at higher energy levels. The fatigue life is longer for the joints welded at an energy of 1400 J than 2000 J at higher cyclic loading levels. The fatigue failure mode changes from nugget pull-out to TTT crack growth with decreasing cyclic loading for the joints welded at 1400 J, while TTT crack growth mode remains at all cyclic loading levels for the joints welded at 2000 J. Fatigue crack basically initiates from the nugget edge, and propagates with “river-flow” patterns and characteristic fatigue striations. Keywords: aluminum alloy; ultrasonic spot welding; EBSD; microstructure; tensile strength; fatigue

Dissimilar metals joining of steel and aluminum alloy by resistance spot welding

2014 ◽  
Vol 32 (2) ◽  
pp. 83-94 ◽  
Author(s):  
Kenji MIYAMOTO ◽  
Shigeyuki NAKAGAWA ◽  
Chika SUGI ◽  
Kenji TSUSHIMA ◽  
Shingo IWATANI ◽  
...  
Keyword(s):  
Aluminum Alloy ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Dissimilar Metals ◽  
Resistance Spot
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