Untersuchungen zur Dauerfestigkeit carbonitrierter Proben aus den Einsatzstählen 18CrNiMo7‐6und 20MnCr5 |
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| Authors: | C. Stöberl H. Bomas B. Clausen F. Hoffmann H.‐W. Zoch |
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| Affiliation: | IWT‐Stiftung Institut für Werkstofftechnik, Bremen, Germany |
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| Abstract: | The endurance limit of carbonitrided specimens of 18CrNiMo7‐6 and 20MnCr5 case hardening steels were examined under bending conditions. Four variants were manufactured differing in heat treatment and surface conditions. Besides conventional gas carburised variants, carbonitrided specimens with a low and a raised nitrogen content of 0.2 and 0.45% at the surface as well as a carbonitrided and ground variant were examined. The specimens were tested with stress ratios R = –1 and 0. Depending on the nitrogen content cyclic loading evokes compressive residual stresses at the specimens' surfaces, caused by elastic‐plastic deformation. Specimens of the ground variant show additionally a decrease of the residual austenite content when cycled. The induced compressive residual stresses are substantially responsible for high endurance limits at both stress ratios and are the key for understanding the beneficial effect of carbonitriding in this regard. |
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| Keywords: | Carbonitrieren Dauerfestigkeit Einsatzstahl Biegewechselfestigkeit Carbonitriding endurance limit case hardening steel bending fatigue |
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