scholarly journals Microstructure and Fracture Behavior of Refill Friction Stir Spot Welded Joints of AA2024 Using a Novel Refill Technique

Metals ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 286 ◽  
Author(s):  
Lipeng Deng ◽  
Shuhan Li ◽  
Liming Ke ◽  
Jinhe Liu ◽  
Jidong Kang
Keyword(s):  
Spot Welding ◽  
Fracture Behavior ◽  
Shear Fracture ◽  
Load Capacity ◽  
Maximum Load ◽  
Fusion Welding ◽  
Tensile Shear ◽  
Friction Stir ◽  
Corona Ring ◽  
Spot Welded

Keyhole at the end of a conventional friction stir welded (FSW) joint is one of the major concerns in certain applications. To address this issue, a novel keyhole refilling technique was developed for conventional friction stir spot welding (FSSW) using resistance spot welding (RSW). A three-phase secondary rectifier resistance welder was adapted for the refill of the keyhole in the 1.5 mm + 1.5 mm friction stir spot welded 2024-T4 aluminum alloy joint. The microstructure and tensile shear fracture behavior were compared for both the unfilled and refilled specimens. The results show that the plug and keyhole are dominated by solid state welding with some localized zones by fusion welding. The refill process significantly improved the maximum load capacity in tensile shear testing as the corona ring is enlarged leading to a larger bonding area. Moreover, the tensile shear fracture occurs in the refilled FSSW specimens at the corona bonding zone, while the fracture occurs at the hook zone in the unfilled keyhole.

Experimental study of nanoelectroplating steel spot welding structure under impact tensile-shear loading

2021 ◽  
Vol 11 (7) ◽  
pp. 1207-1213
Author(s):  
Chunlei Fan ◽  
Huanran Wang ◽  
Dongfang Ma
Keyword(s):  
Dynamic Loading ◽  
Heat Affected Zone ◽  
Static Loading ◽  
Spot Welding ◽  
Fracture Behavior ◽  
Shear Fracture ◽  
Base Material ◽  
Shear Loading ◽  
Tensile Shear ◽  
Softened Zone

The tensile shear fracture behavior of solder joints under impact load influences the whole vehicle’s safety substantially. This paper takes the QP980 steel resistance spot welding (RSW) structure as the research object to study the tensile-shear fracture behavior of the RSW structure under tensile-shear loading. The microstructure observation of the welded spot shows that the metallographic structure is the martensite. The porosity defects in the melting zone are the primary defect reflecting the obvious plate-cracks on both sides of the nugget. The paper demonstrates the Vickers hardness test result of the spot-welded zone. According to the test, the micro-hardness distribution result shows that the higher the martensite, the greater the hardness. A softened zone emerges adjacent to the heat-affected zone on the welded base material interface. The quasi-static and dynamic tensile-shear tests on the QP980 steel RSW lap-joint specimens show that the fracture on the BM is adjacent to the welded spot under quasi-static loading but close to the heat-affected zone under dynamic loading. Under dynamic loading, the weld seam and softened zone of the welded spot have a direct influence on the fracture. On the recovered specimen’s fractured section, there are a large number of apparent dimples on the section of the BM under quasi-static loading and the section of the HAZ under dynamic loading with nucleation, growth, and aggregation of cavitation, resulting in ductile fracture.

scholarly journals Effect of Zn Interlayer Particles on Mechanical Properties and Microstructure of Friction Stir Spot Welding Aluminum Alloy

2018 ◽  
Vol 218 ◽  
pp. 04005
Author(s):  
Lingga Arti Saputra ◽  
Nurul Muhayat ◽  
Triyono
Keyword(s):  
Mechanical Properties ◽  
Spot Welding ◽  
Dwell Time ◽  
Aluminum Matrix ◽  
Friction Stir Spot Welding ◽  
Motor Vehicles ◽  
Shear Load ◽  
Tensile Shear ◽  
Friction Stir ◽  
Spot Welded

Global warming can be reduced by controlling emissions in motor vehicles. Lightweight aluminum materials can lower the engine work so as to reduce fuel consumption.The effect of dwell time on mechanical properties and microstructure friction stir spot welded AA1100 with particle interlayer Zn were investigated. The result shows that the particle interlayer Zn affect to the mechanical properties. The tensile shear load friction stir spot welded AA1100 with particle interlayer Zn is higher than hart of without particle interlayer Zn. In line with tensile shear load that the hardness of friction stir spot welded Al with particle interlayer Zn got the higher hardness than of without particle interlayer Zn. The addition of particle interlayer Zn reduce the hook defect and spread in the aluminum matrix as solid solution.

Mechanical Properties and Fracture Behavior of Friction Stir Spot Welded AZ61 Magnesium Alloys

2010 ◽  
Vol 154-155 ◽  
pp. 498-507 ◽  
Author(s):  
Ben Yuan Lin ◽  
Ju Jen Liu ◽  
Lee Der Lu
Keyword(s):  
Fracture Behavior ◽  
Shear Failure ◽  
Shear Loading ◽  
Stir Zone ◽  
Welding Parameters ◽  
Tensile Shear ◽  
Friction Stir ◽  
Lower Sheet ◽  
Lap Shear ◽  
Spot Welded

In this study, the tensile shear strength and the fracture behavior of friction stir spot welded AZ61 joints in lap-shear configuration were investigated. The heat input was measured in FSSW to help analyze the effect of welding parameters on the strength. The tensile shear failure test was performed in a material testing system. The cross section of the joints and the fracture surface of the failed specimens were analyzed using optical microscopy and scanning electron microscopy. Results show that the weld diameter and the tensile shear load increase with increasing the input heat. The path of the material flow formed during FSSW process would provide a good way for crack propagation. All failed specimens in this study appear the same fracture features and show a circumferential failure mode under tensile shear loading conditions. The failure is initiated from a notch tip in the upper sheet loading side, and then propagates along the interface of the upper and lower sheets, then through the stir zone circumference; finally, a small portion of the lower sheet in the lower sheet loading side is torn off with some part of the stir zone.

Fracture Behavior of Friction Stir Spot Welded Joint

2010 ◽  
Author(s):  
Abdel-Hamid I. Mourad ◽  
Khalifa H. Harib ◽  
Aly El-Domiaty
Keyword(s):  
Penetration Depth ◽  
Spot Welding ◽  
Fracture Behavior ◽  
Fracture Behaviour ◽  
Frictional Heat ◽  
Experimental Program ◽  
Main Process ◽  
Tensile Shear ◽  
Friction Stir ◽  
Lap Shear

The fracture behaviour of lap-shear joints manufactured by friction stir spot welding (FSSW) technique is examined in this paper. Two aluminium sheets of 2.8 mm thickness were welded using different process parameters to form a lap-shear joint. Special tool was designed and fabricated for the stir-spot welding process. Tensile-shear tests were performed to determine the tensile-shear load bearing capacity and toughness of the weld. The stress intensity factor and the J-integral around a weld are determined in order to characterize the fracture behavior. The effect of different main process controlling parameters, e.g., the tool prop pin rotating speed, duration action time and sinking/penetration depth into the lower welded sheet on the weld fracture behaviour has been investigated through an intensive experimental program. Optical and scanning electron microscopes fractographes were obtained to examine the weld fracture modes. The results show that higher frictional heat due to relatively higher tool probe pin rotational speed and penetration depth into the lower sheet produces improved joint static strength and toughness.

scholarly journals Analysis of tensile-shear strength of single and multi-friction stir spot welding joints under fixed welding process conditions

2020 ◽  
Vol 234 (24) ◽  
pp. 4893-4904
Author(s):  
Morteza Asadollahi ◽  
Neda Jabbari ◽  
Soheil Nakhodchi ◽  
Hossein Salimi ◽  
Hamed Haddad Khodaparast
Keyword(s):  
Shear Strength ◽  
Failure Mechanism ◽  
Spot Welding ◽  
Welding Process ◽  
Friction Stir Spot Welding ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Friction Stir ◽  
Welding Joints ◽  
Spot Welded

The tensile-shear strength of AA 5052 single and multi-friction stir spot welding joints were analyzed using experimental, numerical, and analytical approaches. Benchmark specimens were designed and manufactured in a similar manner with respect to industrial practice. Under the fixed welding process condition, the failure mechanism of friction stir spot welded specimens under tensile-shear loading was first determined by using macro- and micro-structural analysis. It is shown that increasing the tool shoulder diameter and the number of friction stir spot weldings may nonproportionally increase the strength of the joints. In the linearly arranged multi-friction stir spot welding joints, the strength of these joints was discussed using analytical approach. It is demonstrated that in certain cases, increasing the nugget diameter is preferred than increasing the number of nuggets. This is only applicable to a certain friction stir spot welding failure mechanism. A finite element model prediction tool was developed to predict the tensile-shear strength of friction stir spot welded joints using the material properties obtained from the measurement of experimental hardness.

scholarly journals Mechanical Properties and Microstructure of Friction Stir Spot Welded 6082-T6 Aluminium Alloy Joint

2019 ◽  
Vol 269 ◽  
pp. 01005 ◽  
Author(s):  
Nurul Muhayat ◽  
Bobby Priatmana Putra ◽  
Triyono
Keyword(s):  
Mechanical Properties ◽  
Spot Welding ◽  
Dwell Time ◽  
Stir Zone ◽  
Grain Structure ◽  
Shear Load ◽  
Tensile Shear ◽  
Friction Stir ◽  
Time Lead ◽  
Spot Welded

Friction stir spot welding (FSSW) can substitute resistance spot welding (RSW) to avoid the problem due to melting materials during welding. In this investigation, a friction stir spot welded 6082 T6 joint was made to study the effect of pin diameter and dwell time on mechanical properties and microstructure with variation of pin diameter and dwell time. In the stir zone, it is observed that the grain structure is fine equiaxed recrystallized grain whereas in the HAZ, it is coarse grain. The increase of pin diameter and dwell time lead to the increase of tensile shear load. The highest tensile-shear load obtained is 4987.1 N at the highest pin diameter of 7 mm and dwell time of 3 seconds, while the lowest one is 788.2 N that obtained at pin diameter pin of 3 mm and dwell time 3 second. The highest micro Vickers hardness obtained at stir zone of 96.2 VHN, while the lowest one is 42.1 VHN.

Effect of Tool Geometry on Strength of Friction Stir Spot Welded Aluminum Alloys

2012 ◽  
Vol 579 ◽  
pp. 109-117 ◽  
Author(s):  
Yuan Ching Lin ◽  
Ju Jen Liu ◽  
Ben Yuan Lin
Keyword(s):  
Tensile Strength ◽  
Shear Strength ◽  
Spot Welding ◽  
Tool Geometry ◽  
Al Alloy ◽  
Tensile Shear Strength ◽  
Tensile Shear ◽  
Friction Stir ◽  
Hook Geometry ◽  
Spot Welded

The effects of tool geometry on the microstructure and tensile shear strength of friction stir spot-welded A6061-T6 Al alloy sheets were investigated in the present study. Friction stir spot welding (FSSW) was carried out at a tool speed of 2500 rpm, plunging rate of 1 mm/s, and dwell time of 3 s. Four types of tools with the same shoulder shape and size, but different pin profiles (threaded cylindrical, smooth cylindrical, threaded triangular, and smooth triangular) were used to carry out FSSW. The mechanical and metallurgical properties of the FSSW specimens were characterized to evaluate the performance of the different tools. Experimental results show that the pin profile significantly alters the hook geometry, which in turn affects the tensile shear strength of the friction stir spot welds. The welds made using the conventional thread cylindrical tool have the largest elongation and yield the highest tensile strength (4.78 kN). The welds made using the smooth cylindrical tool have the lowest tensile strength. The welds made using the threaded triangular and smooth triangular tools both have a tensile-shear load of about 4 KN; however, the welds made using the threaded triangular tool have a better elongation than those made using the smooth triangular tool.

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
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Fracture Mode ◽  
Heat Input ◽  
Tensile Shear ◽  
Microstructural Characteristics ◽  
Friction Stir ◽  
Welding Heat Input ◽  
Mixed Fracture ◽  
Spot Welded

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.

Resistance Spot Welding in Non-Combustible Magnesium Alloy

2020 ◽  
Author(s):  
Xuanyi Shao ◽  
Yukio Miyashita ◽  
Duriyathep Panwised ◽  
Rattana Borrisutthekul
Keyword(s):  
Magnesium Alloy ◽  
Resistance Spot Welding ◽  
Spot Welding ◽  
Shear Test ◽  
Dissimilar Materials ◽  
Maximum Load ◽  
Tensile Shear ◽  
Similar Material ◽  
Resistance Spot ◽  
Surface Polishing

Abstract Resistance spot welding (RSW) was applied to non-combustible magnesium alloy, AX41 (Mg-4%Al-1%Ca) to investigate its weldability. The similar material joint of AX41 and dissimilar materials joint between AX41 and aluminum alloy, AA6061 were welded. Tensile shear test was carried out to evaluate joining strength in the similar and dissimilar materials RSW joints. In case of similar material joints, the maximum load obtained with tensile shear test in AX41 similar material joint was higher than that obtained in AA6061 similar material joint. Moreover, higher maximum load was obtained in a similar material joint without surface polishing compared to joint welded with surface polishing in AX41. In case of the dissimilar materials joint, the maximum load obtained was almost comparable with AX41 similar material joint, however scatter in joint strength was large. Weldability of the dissimilar materials joint became poor by applying surface polishing.

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