On the relation of microstructure and low-cycle fatigue properties of 301LN austenitic stainless steel after reversion annealing

0449852 - ÚFM 2016 RIV CZ eng A - Abstrakt
Chlupová, Alice - Man, Jiří - Polák, Jaroslav - Karjalalinen, L.P.
On the relation of microstructure and low-cycle fatigue properties of 301LN austenitic stainless steel after reversion annealing.
Book of Abstracts. 17th International Conference on the Strength of Materials (ICSMA-17). Brno: Ústav fyziky materiálů AV ČR, v. v. i., 2015 - (Dlouhý, A.; Kunz, L.). s. 50-50. ISBN 978-80-87434-07-9.
[ICSMA-17 International Conference on the Strength of Materials /17./. 09.08.2015-14.08.2015, Brno]
Grant CEP: GA ČR GA13-32665S
Institucionální podpora: RVO:68081723
Klíčová slova: fatigue * austenitic stainless steel * ultrafinegrained material
Kód oboru RIV: JL - Únava materiálu a lomová mechanika

Grain refinement effect on mechanical response of austenitic stainless steel AISI 301LN to monotonic and mainly low-cycle fatigue loading was investigated. Reversion annealing based on the martensite to austenite phase transformation resulted in coarse grained (CG) and ultrafine grained (UFG) microstructure with grain sizes of 14 µm and 1.4 µm respectively. Fatigue behaviour was characterised by cyclic hardening/softening curves, fatigue life curves and using additional analysis of hysteresis loops for both UFG and CG materials. Fully reversed fatigue loading of thin sheet specimens was performed with the help of anti-buckling fixtures in total strain control regime at room temperature. Two times higher yield stress of UFG material in comparison with CG counterpart resulted in considerably different stress amplitudes at the start of cycling. Nevertheless due to more pronounced cyclic hardening of the CG material the stress amplitudes of both materials before fracture are almost identical. UFG material under total strain control conditions has higher fatigue life. Whereas CG material exhibited typical shape of hysteresis loop, a distinct constriction of the loop was detected in case of UFG material. Evolution of the first derivative of both tensile and compression half-loops showed that the constriction effect is most pronounced at the start of cycling and diminishes with increasing number of cycles. To reveal the destabilization of austenitic structure and to evaluate the extent of deformation induced by martensitic transformation Ferritescope measurements were performed prior and after mechanical tests. Profiles of magnetic phase content (i.e. deformation induced martensite) along the specimen gauge length were obtained. The maximum amount of magnetic phase after tensile test reached similar values for both CG and UFG materials. Cyclic loading with the same strain amplitude resulted in higher fraction of martensite in CG material.
Trvalý link: http://hdl.handle.net/11104/0251271