Failure analysis on a leaf spring cracked during hot forming

In this study, failure analysis was conducted on a 51CrV4 steel leaf spring cracked during hot forming by using a light optical and energy dispersive spectroscopy equipped scanning electron microscopes. Microstructural surveys revealed presence of several surface and internal cracks at the prior austenite grain boundaries, where trace elements (Cu, Sn, Sb and Pb) accumulated. Finite element analysis revealed that the location of the crack was the region of the leaf spring where the maximum principle stress developed. It was finally concluded that, the leaf spring material lost its hot ductility under tensile loading at the employed processing temperature upon intergranular liquation.