Notch Effect on Fatigue Behaviour of Microalloyed Forging Steels

Abstract

The fatigue behaviour of a microalloyed forging steel was analysed at two hot-forging temperature levels - one at1240°Ccorresponding to the ordinary heating parameters and the other at1060°Csuited to obtain a finer grain size. The resulting behaviour was then compared with a conventional hardened and tempered steel. Fatigue tests were carried out both on smooth and keyhole-type notched specimens. The fatigue test nucleation was studied on smooth test pieces, and the resulting experimental data were then used to predict the fatigue life of notched specimens.

Contrarily to what happens with hardening and tempering steels, predictions for microalloyed steels are almost never conservative.