Abstract
In this study fatigue testing and defect assessment were carried out on specimens welded with robotic and manual welding using flux cored (FCAW) and metal cored (MCAW) filler materials in order to study the effect of the welding method on the fatigue strength and weld quality. Thirteen different batches were investigated of which two was shot peened before fatigue testing. The local weld geometry was measured for all the specimens before testing. The specimens welded with flux cored weld wire showed the best fatigue strength, small defects and low residual stresses. Large scatter in the fatigue data is observed, especially when manual welding is employed. The few largest defects were removed by the shot peening process, although small defects survived. This led to a smaller scatter in fatigue live for the shot peened specimens. Linear elastic fracture mechanics, LEFM, was employed for analysis of the fatigue test results. The fatigue life predictions using a 2D LEFM FE-model for simulating a continuous cold lap defect along the weld toe showed a qualitative agreement with the fatigue test results. The 2D analysis showed that a continuous cold lap defect should be no more than 0.5 mm deep in order to comply with the requirement of fatigue lives for normal weld quality according to the IIW design rules. For larger defects (> 0.8 mm) an increased toe radius will have a small effect on the fatigue strength. A 3D LEFM analysis of crack growth from a spatter-induced cold lap defect was also carried out. This showed similar trends in crack growth compared to the 2D analysis of a continuous cold lap, although the spatter-induced cold lap defect (semi-elliptical) had a longer fatigue life (x2.7), and hence is less dangerous from a fatigue point of view.
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Barsoum, Z., Jonsson, B. Fatigue Assessment and Lefm Analysis of Cruciform Joints Fabricated with Different Welding Processes. Weld World 52, 93–105 (2008). https://doi.org/10.1007/BF03266657
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DOI: https://doi.org/10.1007/BF03266657