EBSD based studies on various modes of cyclic deformation at 923 K in a type 316LN stainless steel

The study presents an EBSD based investigation on the nature of deformation occurring under different modes of cyclic loading viz. low cycle fatigue (LCF), creep-fatigue interaction (CF) and LCF-creep-HCF. Compared to LCF, cyclic life was found to decrease for CF or LCF-creep-HCF loading conditions....

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Bibliographic Details
Published in:Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2018-04, Vol.723, p.229-237
Main Authors: Sarkar, Aritra, Dash, Manmath Kumar, Nagesha, A., Dasgupta, Arup, Sandhya, R., Okazaki, M.
Format: Article
Language:English
Subjects:
316LN SS
Austenitic stainless steels
Cyclic loads
Deformation
Dislocations
Intergranular fracture
LCF
LCF-creep-HCF
Load
Low cycle fatigue
Materials fatigue
Metals creep
Misalignment
Recovery
Stainless steel
Twinning
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Summary:The study presents an EBSD based investigation on the nature of deformation occurring under different modes of cyclic loading viz. low cycle fatigue (LCF), creep-fatigue interaction (CF) and LCF-creep-HCF. Compared to LCF, cyclic life was found to decrease for CF or LCF-creep-HCF loading conditions. This was attributed to the additional damage contributions from creep in CF cycling and a combination of creep and HCF in LCF-creep-HCF loading conditions, as substantiated through a highly intergranular fracture observed in those cases. Local misorientation map derived from EBSD showed that the misorientation spread is highest for the LCF condition compared to CF and LCF-creep-HCF. This was attributed to the enhanced thermal recovery taking place during CF and LCF-creep-HCF conditions in comparison to LCF. The dislocations generated during cycling rearrange themselves into a stabilized substructure in the form of cells in the above loading conditions leading to a lower value of local misorientation in those cases. This was also accompanied by a significant decrease in number of twins in CF and LCF-creep-HCF conditions compared to LCF. The dislocation-twin interaction responsible for the process of de-twinning was found to be expedited in the former cases owing to a higher thermal recovery.
ISSN:0921-5093
1873-4936
DOI:10.1016/j.msea.2018.02.101