Abstract
In this paper fatigue properties of three groups of unequal thickness unmarked overlap laser welding of the external wallboard connected of type A and B vehicle were studied. In addition, a ...group of overlap penetration welded structures of 1.5mm-301L-HT+0.8mm-301L-DLT is designed to study the impact of penetration rate to the mechanical properties. The influence of the weld geometry and plate combination on fatigue fracture behavior and fatigue property is studied based on the combination of fatigue test and simulation stress analysis. Fatigue studies have shown that in spite of the thickness of the two lap unequal thickness welded plate is disparities -- unmarked non-penetration welding outer plate is thicker but it appears fatigue fracture on the outer plate. The safety fatigue limit of three different non-penetration welded structures of plate combinations and weld structures is close which further proofs that the stress state and microstructure of non-penetration outer plate is not conducive to fatigue fracture. It is consistent with the results of the finite element simulation. The fatigue limit of lap welded structure increase with the increase of plate thickness.
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•Defect-free laser-welded AA5052-H36 overlap joints were prepared using oscillation mode.•Stitch weld orientation influences significantly the fatigue behaviour of overlap ...joints.•Stitch weld orientation and fatigue load influence fracture patterns in overlap joints.•Contrary to static loading, the gap reduces the fatigue performance of overlapped joints.•Seven different mathematical models described satisfyingly the tested joints’ fatigue curves.
This study investigates the fatigue behaviour of overlap laser-welded 1.6 mm thick AA5052-H36 sheets. The oscillation beam laser welding in continuous mode is adopted for preparing defect-free weld seams. Three different stitch-weld orientations (transversal, longitudinal, and diagonal with respect to the load direction, denoted in the present work A, B, and F, respectively) coupled with two different part-to-part gap values (in contact and out-of-range gaps, denoted G00 and G05, respectively) are considered. The vertical configuration showed the highest fatigue resistance and repeatability as well as the highest resistance to crack propagation and the most secure fracture pattern. Finally, the gap decreased the fatigue life in a range of 5–20 % depending on the applied load and the stitch-weld orientation.
•Overlap welded joints of CP Ti and AA2024 were produced by laser welding.•It was found that after TSS test, failure occurs in the columnar HAZ of aluminum.•A comparison of influence of different ...linear energy was revealed.•The two different HAZ of aluminum was compared.
The study results of an overlap welded joint of Commercially Pure Titanium Grade 4 (CP Ti) and Aluminum-Copper Alloy 2XXX series (AA2024) obtained by laser welding without defects in the form of pores and cracks are presented. A microstructure using optical and scanning electron microscopes, a phase composition using X-Ray Diffraction, an electrical resistivity of welded joints were studied. It was found that at tensile shear strength (TSS) testing, failure occurs not only in the brittle intermetallic zone of the welded joint but also in the columnar heat affected zone (HAZ) of aluminum. A 1% of titanium does not have time to diffuse from the HAZ of aluminum at a higher welding speed (150 mm/s), whereas, at a speed of 20% less titanium is not observed in the HAZ of aluminum. The tensile shear strength of samples welded on the titanium side is in the range of 80–120 MPa, depending on the rate of input energy.
This paper presents the research on weldability of magnesium alloy AZ61 sheets by overlap laser welding, adhesive bonding, and laser seam weld bonding processes. Microstructures and mechanical ...properties of the joints are investigated. In overlap laser welding, the joint fractures at the interface between the sheets and maximum shear strength can reach 85% of that of the base metal. Off-center moment during tensile shear test can lead to the strength loss, while the weld edge can also influence the strength as a cracking source. Adhesive bonded joint can offer high tensile shear failure force but low peel strength. Laser weld bonded joint offers higher tensile shear failure force than either laser welded joint or adhesive bonded joint does, and the improved failure load is due to combined contribution of the weld seam and the adhesive. The weld seam can block the adhesive crack propagation, and the adhesive improves the stress distribution, so they can offer a synergistic effect.
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