Fatigue properties of AA6060‐T6 butt welds made by hybrid metal extrusion & bonding

Abstract

The present investigation is concerned with high‐cycle axial fatigue testing of a 2‐mm AA6060‐T6 hybrid metal extrusion & bonding (HYB) butt weld produced in the solid state using AA6082 filler metal addition. The results complement the three‐point bend testing and the tensile testing done in two previous studies. In this study, optical microscope and scanning electron microscope examinations have been carried out to reveal the joint macro/microstructure and document possible surface and root defects deemed to affect fatigue life. In the as‐welded condition, the HYB weld suffers from surface irregularities at the weld face and ‘kissing’ bond formation in the root region. Despite of this, the subsequent testing shows that the fatigue properties exceed those reported for comparable AA6082‐T6 gas metal arc butt welds and matching those reported for corresponding high‐strength laser beam and friction stir weldments.

Fatigue behaviour of butt-lap friction stir welded joints used with aluminum bridge decks

“…Studies on the fatigue behaviour of FSW joints in different applications exist in the literature. Both small-and large-scale fatigue tests have been designed and conducted [4,[16][17][18]24,[26][27][28][41][42][43][44][45][46][47][48][49][50][51][52]. The majority of these tests are for butt [4,18,44,45] and lap-type FSW joints [46][47][48][49][50]; the fatigue behaviour of butt-lap FSW joints of aluminum extrusions has, however, rarely been examined.…”

“…Both small-and large-scale fatigue tests have been designed and conducted [4,[16][17][18]24,[26][27][28][41][42][43][44][45][46][47][48][49][50][51][52]. The majority of these tests are for butt [4,18,44,45] and lap-type FSW joints [46][47][48][49][50]; the fatigue behaviour of butt-lap FSW joints of aluminum extrusions has, however, rarely been examined. Texier et al [17] investigated the fatigue behaviour of butt-lap FSW and fusion-based GMAW (gas metal arc welding) joints from tensile fatigue tests on small-scale specimens extracted from AA 6061-T6 alloy extruded profiles used in the automotive industry (joint thickness ≈ 9.4 mm).…”

A frequency‐domain approach for damage detection in welded structures

“…However, as is well‐known, the fatigue strength of a welded component in presence of multiaxial cyclic loading is significantly lower than that of an unwelded one (even if the components are made of the same material) 2 . In particular, the factors causing the above strength reduction 3–5 are residual stresses, 6–9 thermal distortions, 10 defects caused by partial penetration, 11 and material microstructural imperfections 12 …”

“…1 However, as is wellknown, the fatigue strength of a welded component in presence of multiaxial cyclic loading is significantly lower than that of an unwelded one (even if the components are made of the same material). 2 In particular, the factors causing the above strength reduction [3][4][5] are residual stresses, [6][7][8][9] thermal distortions, 10 defects caused by partial penetration, 11 and material microstructural imperfections. 12 Moreover, complex time variable load histories applied to welded components result in severe stress/ strain gradients at the weld toes/roots leading to fatigue damage near such critical regions.…”

Fatigue Modeling and Numerical Analysis of Re-Filling Probe Hole of Friction Stir Spot Welded Joints in Aluminum Alloys

“…However, re-filling the probe hole has no considerable effect on the fatigue strength. Several recent studies [ 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ] used different loading conditions and different viable approaches to investigate the tensile strength and fatigue life of joints and metallic structures.…”