High-temperature low-cycle fatigue behavior of novel austenitic ODS steels

Straßberger, Luis; Chauhan, Ankur; Gräning, Tim; Czink, Steffen; Aktaa, Jarir

doi:10.1016/j.ijfatigue.2016.08.018

Cited by 16 publications

(4 citation statements)

References 14 publications

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“…41 As can be seen from Figure 10, in comparison with conventional non-ODS P91, the studied ODS steels as well as ODS P91 offer comparable lifetime at higher strain amplitudes (>±0.5%) and much higher lifetime under lower strain amplitudes (<±0.5%). Similar results have been also reported by others, see Ukai and Ohtsuka 9 and Straßberger et al 14,15 However, this is not surprising since stronger materials are known to offer better cyclic strain-life under lower strain amplitudes and ductile materials are acclaimed to perform better under higher strain amplitudes. 42 This is due to the fact that strong materials resist imposed strain elastically on the basis of their strength, while ductile materials resist strain plastically on the basis of their ductility.…”

Section: Discussionsupporting

confidence: 88%

“…At present, the knowledge of LCF behaviour of ODS steels is limited since only few studies were dedicated to this issue. [8][9][10][11][12][13][14][15] However, these few studies successfully demonstrate the significance of oxide dispersion strengthening with respect to the cyclic properties. In comparison with the non-ODS variants, the ODS steels offer higher cyclic stress levels with significantly lower inelastic strain amplitudes.…”

Section: Introductionmentioning

confidence: 99%

“…This stability can be judged by straining material cyclically in the regime of elastic‐plastic loading, which yields low‐cycle fatigue (LCF). At present, the knowledge of LCF behaviour of ODS steels is limited since only few studies were dedicated to this issue . However, these few studies successfully demonstrate the significance of oxide dispersion strengthening with respect to the cyclic properties.…”

Section: Introductionmentioning

confidence: 99%

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Towards improved ODS steels: A comparative high‐temperature low‐cycle fatigue study

Chauhan

Walter

Aktaa

2017

Fatigue Fract Eng Mat Struct

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Within the frame of this work, the mechanical behaviour of a bimodal ferritic 12Cr‐ODS steel as well as of a ferritic‐martensitic 9Cr‐ODS steel under alternating load conditions was investigated. In general, strain‐controlled low‐cycle fatigue tests at 550°C and 650°C revealed similar cyclic stress response. At elevated temperatures, the two steels manifest transitional stages, ie, cyclic softening and/or hardening corresponding to the small fraction of the cyclic life, which is followed by a linear cyclic softening stage that occupies the major fraction of the cyclic life until failure. However, it is clearly seen that the presence of the nano‐sized oxide particles is certainly beneficial, as the degree of cyclic softening is significantly reduced compared with non‐ODS steels. Besides, it is found that both applied strain amplitude and testing temperature show a strong influence on the cyclic stress response. It is observed that the degree of linear cyclic softening in both steels increases with increasing strain amplitude and decreasing test temperature. The effect of temperature on inelastic strain and hence lifetime becomes more pronounced with decreasing applied strain amplitude. When analysing the lifetime behaviour of both ODS steels in terms of inelastic strain energy calculations, it is found that comparable inelastic strain energies lead to similar lifetimes at 550°C. At 650°C, however, the higher inelastic strain energies of 12Cr‐ODS steel result in significant lower lifetimes compared with those of the 9Cr‐ODS steel. The strong degradation of the cyclic properties of the 12Cr‐ODS steel is obviously linked to the fact that the initial hardening response appears significantly more pronounced at 650°C than at 550°C. Finally, the obtained results depict that the 9Cr‐ODS steel offers higher number of cycles to failure at 650°C, compared with other novel ODS steels described in literature.

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Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Towards improved ODS steels: A comparative high‐temperature low‐cycle fatigue study

Chauhan

Walter

Aktaa

2017

Fatigue Fract Eng Mat Struct

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“…However, necking due to plastic deformation was observed near the upper and lower surfaces of the test piece. This surface fracture morphology is clearly different from that observed for high-temperature fatigue fractures in stainless steel and nickel-based ODS alloys, thereby suggesting that a different fracture mechanism occurs[26][27][28][29].…”

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confidence: 58%