Issue 40

V. Mazánová et alii, Frattura ed Integrità Strutturale, 40 (2017) 162-169; DOI: 10.3221/IGF-ESIS.40.14 162 Multiaxial elastoplastic cyclic loading of austenitic 316L steel V. Mazánová, J. Polák, V. Škorík, T. Kruml Institute of Physics of Materials, Academy of Sciences of the Czech Republic mazanova@ipm.cz polak@ipm.cz, http://orcid.org/ 0000-0002-0457-4680 skorik@ipm.cz kruml@ipm.cz, http://orcid.org/ 0 000-0002-8855-1709 A BSTRACT . Cyclic stress-strain response and fatigue damage character has been investigated in austenitic stainless steel 316L. Hollow cylindrical specimens have been cyclically deformed in combined tension-compression and torsion under constant strain rate condition and different constant strain and shear strain amplitudes. In-phase and 90° out-of-phase cyclic straining was applied and the stress response has been monitored. Cyclic hardening/softening curves were assessed in both channels. Cyclic softening followed for higher strain amplitudes by long-term cyclic hardening was observed. Cyclic stress-strain curves were determined. Study of the surface damage in fractured specimens revealed the types and directions of principal cracks and the sources of fatigue crack initiation in slip bands. K EYWORDS . Multiaxial cyclic loading; 316L steel; Cyclic stress-strain curve; Crack initiation. Citation: Mazánová, V., Polák, J., Škorík, V., Kruml, T., Multiaxial elastoplastic cyclic loading of austenitic 316L steel, Frattura ed Integrità Strutturale, 40 (2017) 162-169. Received: 09.01.2016 Accepted: 10.02.2017 Published: 01.04.2017 Copyright: © 2017 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION yclic plastic response and damage evolution in elastoplastic cyclic loading of stainless steels, specifically 316L steel, has been studied mostly in tension-compression (see e.g.[1, 2]) but also in torsion [3] and less frequently in multiaxial loading [4, 5]. Characteristic feature of cyclic plastic straining of 316L steel at room and depressed temperatures is the localization of the cyclic plastic strain. The localization of the cyclic strain into persistent slip bands (PSBs) influences its cyclic plastic response and results in formation of persistent slip markings (PSMs) in which fatigue cracks initiate. The subject of the present contribution is to extend the study of the cyclic plastic response and early fatigue damage to tubular specimens of 316L austenitic steel subjected to cyclic tension-compression and torsion biaxial cyclic loading. Simultaneously the early stages of the fatigue damage in the form of PSMs and initiation of fatigue cracks under in-phase and 90°out-of phase straining are reported. C