High temperature fatigue tests of un-notched and notched specimens made of 40CrMoV13.9 steel

The present paper summarizes data from uniaxial-tension stress-controlled fatigue tests on specimens made of 40CrMoV13.9 steel. Tests are performed varying temperature, from room temperature up to 650 degrees C. This steel is commonly employed for hot-rolling of metals and it is subjected, in service, to a combination of mechanical and thermal loadings. Two geometries are considered: plain specimens and plates weakened by symmetric V-notches, with opening angle and tip radius being equal to 90 degrees and 1 mm, respectively. The present work is motivated by the fact that, at the best of authors' knowledge, only a limited number of works dealing with high-temperature fatigue are reported in the literature for the medium/high cycle fatigue regime; in particular, no results seem to be available for 40CrMoV13.9 steel when tested at elevated temperature in the presence of notch effects. After a brief review of the recent literature, the experimental procedure is described in detail and the new data from un-notched and notched specimens are summarized in terms of stress range, at the considered temperatures, for a total of 60 new experimental data. Finally, fatigue data from un-notched and notched specimens are re-analyzed by means of the mean value of the strain energy density (SED), employed here as the critical fatigue parameter, able to summarize in the same scatter band data from different temperatures.