Étude comparative des caractéristiques mécaniques de boulons en acier 42CrMo4 de classe 8.8 selon le processus de fabrication
Résumé
In this article, we will present the results of a comparative study of the mechanical characteristics of 42CrMo4 steel bolts manufactured in standard and special method. This study principally carries on the influence on the mechanical characteristics of the chronology of thermal treatment and cold rolling that interfere in the manufacture procedure of these screws. This chronology does not seem to have influence on the static behaviour of the bolts while the influence on fatigue performances is very important. Besides, independently of the manufacture type, we were able to notice that the zones of rupture are different between static and dynamic tests. In the first case, the rupture takes place in the free thread of the bolt while in dynamic case, the rupture occurs at the level of the first thread taken with the nut. These differences on behaviours observed experimentally corroborated with the finite element models that we implemented in the framework on the held in service of the bolted assemblies.