Study About the Stress Concentration Susceptibility of the Tirefond Screw Applied in Brazilian Railroads.

Ana Luiza Soares Cezário¹; Geraldo Lúcio de Faria¹; Leonardo Barbosa Godefroid¹; Luiz Cláudio Cândido¹

¹ Universidade Federal de Ouro Preto

doi:10.20906/CPS/COB-2015-0877

Resumo

The Tirefond screw is an important structural component of railroads. It is a fixation component, responsible by the support of the plat fixation, which guarantees the stability of rails. This component is commonly produced in Brazil by hot conformation procedures of low carbon steels. However, with the increasing of transported load per train wheel in last years, this component have been often failing in service. Aiming to understand the effects of screw fillets on mechanical behavior of Tirefond screw, this work present a study about the stress concentration susceptibility of the actual low carbon steel used in this component manufacturing. Chemical analysis were done in a optical emission spectrometry equipment; microstructural analysis were performed in optical and scanning electron microscopes; tension and hardness tests were realized. Specimens submitted to tension tests were machined in two different conditions: with and without a notch in the middle of their utile area. The results showed that the steel used in Brazilian Tirefond screw are a SAE1015 with a very heterogeneous microstructure. The mechanical tests have confirmed that this steel has a high stress concentration susceptibility and this is a dangerous conditions for actual geometry of this component.

Palavras-chave: Tirefond Screw; Stress Concentration; Tension Test