Nikolova L.Yordanova R.Angelova D.2024-07-162024-07-162024-07-162024-07-162014-02-251314-74711314-7978SCOPUS_ID:84894056090https://rlib.uctm.edu/handle/123456789/1038Fatigue behavior of spring steel at different stress ranges was investigated. The specimens were machined in hour-glass shape with polished surface and were subjected to symmetric cyclic rotating-bending fatigue in air and room temperature to fracture. Fatigue life time data was obtained and Wöhler curve of the investigated steel at different conditions is plotted. A mathematical description of the obtained results is presented. The fatigue test results are filled out with images and analysis of the fracture surface made with scanning electron microscope. A replication technique is used for short fatigue-crack growth monitoring for two specimens. The experimental data are presented in plots ``Crack lengths, a - cycles, N``.enArticle