Analysis of the Thermomechanical Fatigue Behavior of Fully Ferritic High Chromium Steel Crofer®22 H with Cyclic Indentation Testing

The 22 wt.% Cr, fully ferritic stainless steel Crofer®22 H has higher thermomechanical fatigue (TMF)- lifetime compared to advanced ferritic-martensitic P91, which is assumed to be caused by different damage tolerance, leading to differences in crack propagation and failure mechanisms. To analyze th...

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Bibliographic Details
Published inApplied sciences Vol. 10; no. 18; p. 6461
Main Authors Blinn, Bastian, Görzen, David, Fischer, Torsten, Kuhn, Bernd, Beck, Tilmann
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 16.09.2020
Subjects
Chromium
Chromium steel
Chromium steels
Cooling
Crack propagation
Crack tips
cyclic hardening potential
cyclic indentation test
Damage tolerance
Deformation analysis
Failure mechanisms
Fatigue
Ferritic stainless steel
Grain boundaries
Hardness tests
Indentation
Investigations
Mechanical properties
Metal fatigue
Microscopy
microstructural evolution
PhyBaLCHT
Power plants
Solid solutions
Stainless steel
thermomechanical fatigue
Thermomechanical properties
Germany
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Summary:The 22 wt.% Cr, fully ferritic stainless steel Crofer®22 H has higher thermomechanical fatigue (TMF)- lifetime compared to advanced ferritic-martensitic P91, which is assumed to be caused by different damage tolerance, leading to differences in crack propagation and failure mechanisms. To analyze this, instrumented cyclic indentation tests (CITs) were used because the material’s cyclic hardening potential—which strongly correlates with damage tolerance, can be determined by analyzing the deformation behavior in CITs. In the presented work, CITs were performed for both materials at specimens loaded for different numbers of TMF-cycles. These investigations show higher damage tolerance for Crofer®22 H and demonstrate changes in damage tolerance during TMF-loading for both materials, which correlates with the cyclic deformation behavior observed in TMF-tests. Furthermore, the results obtained at Crofer®22 H indicate an increase of damage tolerance in the second half of TMF-lifetime, which cannot be observed for P91. Moreover, CITs were performed at Crofer®22 H in the vicinity of a fatigue crack, enabling to locally analyze the damage tolerance. These CITs show differences between crack edges and the crack tip. Conclusively, the presented results demonstrate that CITs can be utilized to analyze TMF-induced changes in damage tolerance.
ISSN:2076-3417
2076-3417
DOI:10.3390/app10186461