Elucidation of fatigue characteristics and fracture mechanism of friction stir spot‐welded tension–shear joint steels

The energy evolution, fatigue life and failure behaviour of dissimilar Al/steel keyhole-free Friction stir spot welding (FSSW) joints were studied under different fatigue loads. The absorption energy of fatigue fracture, the fracture mechanism and the sensitivity of the fatigue limits to the fatigue load parameters were analysed. It was found that the stress ratio R determines the fatigue limit Ff, while the fatigue limit Ff is not sensitive to the loading frequency. The high-frequency fatigue load will increase the displacement deformation μ and fatigue fracture absorption energy Ea of the spot-welded joint, which are larger under asymmetric fatigue loading than those under symmetrical fatigue loading. At the same time, the symmetrical fatigue load can form the steady-state hysteresis loop, while asymmetric fatigue loading cannot, but asymmetric fatigue loading exhibits the displacement increment of fatigue softening. The fracture failure of spot-welded joints is a multiple crack source and the mixed-mode of ductile and brittle fracture mechanism, which exhibits typical fatigue striations in the fatigue fractures.

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3-Dimensional observation of the interior fatigue fracture mechanism on friction stir spot welded using 300MPa-class automobile steel sheets

Proceedings of the 1st International Joint Symposium on Joining and Welding ◽

10.1533/978-1-78242-164-1.435 ◽

2013 ◽

pp. 435-442 ◽

Cited By ~ 2

Author(s):

S. Joy-A-Ka ◽

T. Hirano ◽

H. Akebono ◽

M. Kato ◽

A. Sugeta ◽

...

Keyword(s):

Fatigue Fracture ◽

Fracture Mechanism ◽

3 Dimensional ◽

Friction Stir ◽

Steel Sheets ◽

Automobile Steel ◽

Spot Welded ◽

Fatigue Fracture Mechanism

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Developing an Empirical Relationship to Predict the Strength of Friction Stir Spot Welded Dissimilar Joints of Aluminum Alloy with Carbon Steel

Indian Welding Journal ◽

10.22486/iwj/2016/v49/i3/126036 ◽

2016 ◽

Vol 49 (3) ◽

pp. 61

Author(s):

S. Manickam ◽

C. Rajendran ◽

V. Balasubramanian

Keyword(s):

Aluminum Alloy ◽

Carbon Steel ◽

Empirical Relationship ◽

Dissimilar Joints ◽

Friction Stir ◽

Spot Welded

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On the association between microhardness, corrosion resistance and microstructure of probeless friction stir spot welded Al-Li joint

Journal of Materials Research and Technology ◽

10.1016/j.jmrt.2021.07.120 ◽

2021 ◽

Author(s):

Q. Chu ◽

S.J. Hao ◽

W.Y. Li ◽

X.W. Yang ◽

Y.F. Zou ◽

...

Keyword(s):

Corrosion Resistance ◽

Friction Stir ◽

Spot Welded

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Microstructural Characteristics and Mechanical Properties of Friction Stir Spot Welded 2A12-T4 Aluminum Alloy

Advances in Materials Science and Engineering ◽

10.1155/2013/719306 ◽

2013 ◽

Vol 2013 ◽

pp. 1-10 ◽

Cited By ~ 3

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.

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