Metallurgical characterization and computational simulation of a screw spike aiming to improve its performance in railways.

Abstract

The screw spike is an important structural component of railroads. It is a fixation component responsible for supporting the plat fixation on the sleeper and guarantees the railroad stability. This component is commonly produced by hot forming processing of low carbon steels. In Brazil, this component has been often failing in service due to the increase in the transported loads by trains in last years. This work investigated the stress concentration susceptibility of this component in order to understand the effects of screw threads on the mechanical behavior of the screw spike. Chemical and microstructural analyses were performed using optical emission spectrometry and optical microscopy; tensile and hardness tests were also executed. Computational models of static loading were used to determine the stress distribution along the actual geometry of the studied screw and to understand the main causes of recurrent failures. The use of appropriate relations of Mechanics of Materials associated with computational simulations allowed the proposal of some changes in the screw spike original project aiming to improve its performance in service.