Fracture analysis of dissimilar Al-Al friction stir welded joints under tensile/shear loading

2018 ◽  
Vol 41 (9) ◽  
pp. 2040-2053 ◽  
Author(s):  
A.R. Torabi ◽  
M.H. Kalantari ◽  
M.R.M. Aliha
Keyword(s):  
Welded Joints ◽  
Fracture Analysis ◽  
Shear Loading ◽  
Tensile Shear ◽  
Friction Stir

Microstructure and mechanical properties of 6061-T6 aluminum alloy and Q235 steel via probeless friction stir extrusion joining

2021 ◽  
Author(s):  
Peng Zhang ◽  
Shengdun Zhao ◽  
Chuanwei Zhang ◽  
Zheng Chen ◽  
Jiaying Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Composite Structures ◽  
Rotation Speed ◽  
Shear Loading ◽  
Tensile Shear ◽  
Q235 Steel ◽  
Friction Stir ◽  
Fracture Failure ◽  
Friction Stir Extrusion

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.

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.

Friction Stir Lap Joining of Blanks under Different Conditions

2015 ◽  
Vol 651-653 ◽  
pp. 1433-1438 ◽  
Author(s):  
Carlo Bruni ◽  
Alessio D'Orazio ◽  
Mohamad El Mehtedi
Keyword(s):  
Numerical Simulation ◽  
Shear Strength ◽  
Numerical Simulations ◽  
Welded Joints ◽  
Rotational Velocity ◽  
Tool Geometry ◽  
Tensile Shear Strength ◽  
Trial And Error ◽  
Tensile Shear ◽  
Friction Stir

The present investigation aims at studying the effect of the tool geometry and of rotational velocity of the tool, at different welding velocities, on the tensile shear strength of the friction stir welded joints realised with blanks of different thicknesses. The proposed trial and error methodology was based on experiments, numerical simulations and microstructure observations.It was observed that, at the lowest rotational velocity, the slender tool determines tensile shear strength values lower than those obtained with the thick tool in particular at the highest welding velocity investigated. The numerical simulation evidenced a wider stirred zone for the thick tool when compared with that realised with the slender tool at the lowest rotational velocity. Microstructure observations evidenced that the increase in the welding velocity determines reduced stirred zones and an homogenisation of material particularly relevant for the slender tool.

Effect of Tool Pin Profile on the Hook Geometry and Mechanical Properties of a Friction Stir Spot Welded AA6082-T6 Aluminum Alloy

2020 ◽  
Author(s):  
HAKAN AYDIN ◽  
OGUZ TUNCEL ◽  
MUMIN TUTAR ◽  
ALI BAYRAM
Keyword(s):  
Spot Welding ◽  
Dwell Time ◽  
Shear Loading ◽  
Weld Strength ◽  
Tensile Shear ◽  
Friction Stir ◽  
Weld Width ◽  
Ductile Fractures ◽  
Hook Geometry ◽  
Tool Pin

AA6082-T6 alloy was joined by friction stir spot welding using five different pin profiles, such as a cylindrical, conical, triangular, hexagonal and cylindrical with two grooves, at different dwell time. The joints welded by cylindrical pins had larger effective weld width. But, grooves on the cylindrical pin decreased the effective weld width. The hook was bent downward from the interface of the sheets in the weld made with hexagonal pin, which had the smallest effective weld width. When conical pin was used, effective weld width increased with increasing the dwell time. In the case of using tools with cylindrical and conical pins, HAZ hardness was relatively lower. With increasing dwell time, HAZ hardness of the joints made with conical pin decreased. Effective weld width determined the weld strength under the tensile shear loading condition: Larger effective weld width resulted in higher weld strength. Weld strength of the joints made with cylindrical pin was higher. The joints fabricated with hexagonal pin had the lowest weld strength. In general, higher dwell time led to higher weld strength. The welds with the higher strength experienced both brittle and ductile fractures, while the joints with the lower strength exhibited completely brittle fracture.

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