Fatigue failure of a flash butt welded rail.

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Medium carbon steel rails are commonly jointed by means of a flash butt welding procedure. To ensure an adequate service life for the structural component commonly subjected to fatigue loading, a rigorous quality control should be performed, both in welding parameters and in the surface quality of the welded joint. This work investigated the cause of a recurrent failure in a railway, with cracking always initiated in the rail in the region of the welded joint. All standard procedures of failure analysis were applied, with a careful assessment of the material characteristics and the fractured surface. It was concluded that fatigue cracks initiated near the weld bead and spread in a brittle mode, leading to premature fracture of the material. An in-depth analysis of the early cracks showed that the surface finishing of the weld bead was not appropriate, generating undesirable stress concentration. A recommendation to change the procedure of surface finishing of welded joint was held, aiming to decrease the number of accidents on the railway line.
Rails, Flash butt welding, Cracking
GODEFROID, L. B. et al. Fatigue failure of a flash butt welded rail. Procedia Materials Science, v. 3, p. 1896-1901, 2014. Disponível em: <http://www.sciencedirect.com/science/article/pii/S2211812814003071>. Acesso em: 09 abr. 2015.