• TITLE: EFFECT OF ION NITRIDING ON FATIGUE BEHAVIOR OF STEEL 35HGS
• AUTHOR(S): V. Dunchev, J. Capek, M. Atanasov
• ABSTRACT: In this article the fatigue behavior of specimens made of 35HGS low-alloyed steel has been investigated. A comparative analysis has been made for the effect of hardening process with subsequent grinding and ion nitriding process. For this purpose, five groups of specimens have been manufactured. The first group of specimens has been subjected to hardening and grinding. The other four groups of specimens have been subjected to ion nitriding with a different process duration - 4, 8, 12 and 16 hours, respectively. The experimental study has been conducted in two stages- cyclic bending fatigue tests and residual stresses assessment trough X-ray diffraction analysis. It has been established that the ion nitriding process has a more favorable effect on fatigue life in the field of high-cycle fatigue compared to the quenching process followed by grinding. The positive effect by the quenching and grinding has been observed in the field of low- cycle fatigue. The highest fatigue limit )MPa800( 1   has been obtained for the specimens subjected to ion nitriding for a duration of 4 hours. The X-ray diffraction results show that the ion nitriding process provides greater in absolute value compressive residual stresses compared to the quenching and grinding process. It has been established that the distribution in depth of the axial and hoop residual stresses created after ion nitriding is very similar. A different trend has been established between the obtained fatigue limits and the intensity of the compressive residual stress zone.
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