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.

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

2016 ◽  
Author(s):  
Kai Chen ◽  
Xun Liu ◽  
Jun Ni
Keyword(s):  
Aluminum Alloy ◽  
Cross Sections ◽  
Spot Welding ◽  
Dwell Time ◽  
High Strength ◽  
Friction Stir Spot Welding ◽  
Thin Layers ◽  
Weld Strength ◽  
Friction Stir ◽  
Alloy 6061

Friction stir spot welding (FSSW) process has been successfully applied for joining aluminum alloy 6061 to TRIP 780/800 steel. Effects of tool plunge speed and dwell time on the weld strength were studied through design of experiments and analysis of variance. It is shown that dwell time is a more dominant parameter in affecting the weld strength than plunge speed. Cross sections of weld specimens show the formation of hook with a swirling structure. Higher magnified SEM view with EDS analysis reveals the swirling structure to be composed of alternating thin layers of steel and Al-Fe intermetallic compounds (IMCs). During tensile shear test, cross nugget failure is the only failure mode. Cracks are initiated in the swirling structure at the tensile side of the weld nugget and cleavage feature can be observed on the fractured surface.

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.

Experimental Study and Numerical Modeling of Friction Stir Spot Welding of Pure Copper Lap Joint

2014 ◽  
Author(s):  
Ahmed Kamal Mahgoub ◽  
Abdelaziz Bazoune ◽  
Fadi A. A. Al-Badour ◽  
Abdelrahman Shuaib ◽  
Gihad Mohamed Karrar
Keyword(s):  
Experimental Study ◽  
Spot Welding ◽  
Dwell Time ◽  
Pure Copper ◽  
Friction Stir Spot Welding ◽  
Fusion Welding ◽  
Weld Strength ◽  
Tool Rotational Speed ◽  
Lap Joint ◽  
Friction Stir

Friction stir spot welding (FSSW) is an appropriate process to join materials that are difficult to weld using fusion welding, such as copper. In this paper, an experimental study to weld lap joint of pure copper plates having a dimensions of 100 × 30 × 2 mm is performed, successful spot weld is obtained at tool rotational speed of 1200 rpm, feed rate of 20 mm/min for dwell time of 2 seconds. The tool used in the FSSW has a threaded pin of 5 mm diameter, length of 3.7 mm, and a scrolled shoulder of 11.52 mm diameter. Tensile test and microhardness were performed for the joint and it showed reasonable weld strength. In addition, a numerical model was developed, and the estimated temperatures as well as weld macrostructure matched very well with experimental results.

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 Study the microstructure and mechanical properties of dissimilar friction stir spot welding of carbon steel 1006 to aluminum alloy aa2024-t3

2018 ◽  
Vol 7 (4.1) ◽  
pp. 3037
Author(s):  
Isam Tareq Abdullah ◽  
Zaman Khalil Ibrahim ◽  
Ahmed Ibrahim Razooqi
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Carbon Steel ◽  
Spot Welding ◽  
Dwell Time ◽  
Dissimilar Materials ◽  
Friction Stir Spot Welding ◽  
Shear Load ◽  
Tensile Shear ◽  
Friction Stir

Friction stir spot welding-FSSW has been suggested as effectual process to welding difficult materials such as dissimilar materials and thin sheet of metal alloys. In this study, using dissimilar materials were welded carbon steel-1006 on upper plate and aluminum alloy AA2024-T3 on lower plate. Macrostructure, micro-structural analysis and mechanical properties of the joints are done. The effect of penetration depth, dwell time and spindle speed on tensile shear load are investigated with invariable of other parameter during welding process. The maximum tensile shear load (3.31KN) was occurred when using 0.4mm of penetration depth, 10 sec of dwell time and 1400 rpm of spindle speed. Also, two type of failure shape was observed interfacial fracture of carbon steel sheet and pull-out fracture of AA2024-T3 sheet.

scholarly journals Simultaneous Effect of Tool Rotation and Dwell Time on Quality of Dissimilar AA5052-Copper Joints Fabricated by Friction Stir Spot Welding

2021 ◽  
Author(s):  
Aydin Jadidi ◽  
Reza Bagherian Azhiri ◽  
Amir Baghdadchi ◽  
Abolfazl Salmani Bideskan
Keyword(s):  
Shear Strength ◽  
Spot Welding ◽  
Dwell Time ◽  
Quality Characteristics ◽  
Friction Stir Spot Welding ◽  
Lap Joints ◽  
Lap Shear Strength ◽  
Friction Stir ◽  
Lap Shear ◽  
Rotary Speed

Abstract In the present study, lap joints of dissimilar 5052 aluminum alloy and pure copper were fabricated by friction stir spot welding process. The work was aimed to find effect of parameters such as tool rotary speed (1000, 1400 and 2000 RPM) and dwell time (5, 10 and 15s) on microstructure and strength properties of lap joints. Also, statistical models of the quality characteristics were developed to understand which interaction has dominant effect on quality characteristics. Research findings showed that to obtain sound joints with high lap shear strength tool rotary speed of 2000 rpm and dwell time of 5s should be selected. It provides sufficient heat input and prevents the excessive material softening. On the other hand, to achieve maximum hardness, 2000 rpm tool rotary speed should be chosen to provide enough heat for formation of intermetallic compound and 10s dwell time should be used prevent enough time for microstructure refining. Moreover, from the statistical analyses, it was found that dwell time and tool speed are the significant factor for lap shear strength and hardness, respectively. In order to attain simultaneous maximum strength and hardness, tool speed of 2000 rpm and dwell time of 8 s should be used. In such condition lap shear strength of 1755 N and hardness of 77 V are achieved with desirability of 85%.

scholarly journals Refill Friction Stir Spot Welding Al Alloy to Copper via Pure Metallurgical Joining Mechanism

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Zhikang Shen ◽  
Yuquan Ding ◽  
Wei Guo ◽  
Wentao Hou ◽  
Xiaochao Liu ◽  
...  
Keyword(s):  
Spot Welding ◽  
Friction Stir Spot Welding ◽  
Alloy Sheet ◽  
Weld Strength ◽  
Al Alloy ◽  
Hardness Profile ◽  
Copper Sheet ◽  
Welding Condition ◽  
Friction Stir ◽  
Lap Shear

AbstractThe current investigation of refill friction stir spot welding (refill FSSW) Al alloy to copper primarily involved plunging the tool into bottom copper sheet to achieve both metallurgical and mechanical interfacial bonding. Compared to conventional FSSW and pinless FSSW, weld strength can be significantly improved by using this method. Nevertheless, tool wear is a critical issue during refill FSSW. In this study, defect-free Al/copper dissimilar welds were successfully fabricated using refill FSSW by only plunging the tool into top Al alloy sheet. Overall, two types of continuous and ultra-thin intermetallic compounds (IMCs) layers were identified at the whole Al/copper interface. Also, strong evidence of melting and resolidification was observed in the localized region. The peak temperature obtained at the center of Al/copper interface was 591 °C, and the heating rate reached up to 916 °C/s during the sleeve penetration phase. A softened weld region was produced via refill FSSW process, the hardness profile exhibited a W-shaped appearance along middle thickness of top Al alloy. The weld lap shear load was insensitive to the welding condition, whose scatter was rather small. The fracture path exclusively propagated along the IMCs layer of Cu9Al4 under the external lap shear loadings, both CuAl2 and Cu9Al4 were detected on the fractured surface on the copper side. This research indicated that acceptable weld strength can be achieved via pure metallurgical joining mechanism, which has significant potential for the industrial applications.

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