High temperature tensile properties of oxide dispersion strengthened T91 and their correlation with microstructural evolution

Straßberger, Luis; Litvinov, D.; Aktaa, Jarir

doi:10.1179/1743284714y.0000000562

Cited by 15 publications

(5 citation statements)

References 15 publications

(22 reference statements)

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“…On the other hand, at higher temperatures, the recovery and damage induced by the creep lead to a decrease in the ductility. [21][22] Figure 7 shows the hardness (HV10) test results for both materials without deformation and after the applications of (5,8,20 and 50) % deformation, and at different annealing times of (0, 10, 20 and 40) h at 1200°C. A Vickers hardness test was performed using a ZWICK/ It can be seen that with the increasing deformation, there is almost no change in the hardness of either material for any of the holding times.…”

Section: Test Group Amentioning

confidence: 99%

Using thermomechanical treatments to improve the grain growth of new-generation ODS alloys

Khalaj¹,

Jirková²,

Mašek³

et al. 2018

Mater. Tehnol.

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In order to achieve specific mechanical properties and structures of a material, a combination of new technologies together with an unconventional use of different types of materials could be an asset. Powder metallurgy, involving a metal matrix and dispersed stable particles, in combination with mechanical alloying and hot consolidation could be a solution. This paper describes the thermomechanical characteristics of new oxide-dispersion-strengthened (ODS) alloys with a Fe-Al matrix in terms of changes in the grain-size distribution. Recrystallization and grain growth were investigated over a range of temperatures and deformations. The results show that the grain-growing process in the new ODS alloys is significantly affected by the thermomechanical treatment, leading to the maximum grain size within 20-h annealing at 1200°C. They are analysed using different methods, including optical microscopy.Da bi lahko izdelali materiale s specifi~nimi mehanskimi lastnostmi in strukturo, moramo izbirati kombinacijo ve~razli~nih novih tehnologij skupaj z nekonvencionalno uporabo razli~nih vrst materialov. Kot re{itev se ponuja tehnologija metalurgije prahov, s katero lahko ustvarimo me{anico kovinskih prahov in stabilnih oksidnih delcev. Tej sledi kombinacija mehanskega legiranja in vro~e konsolidacije. V~lanku avtorji opisujejo termomehanske lastnosti nove z oksidi disperzijsko utrjene (ODS; angl: Oxide Dispersion Strengthened) zlitine s Fe-Al matrico s poudarkom na spremembah porazdelitve velikosti kristalnih zrn. Avtorji so raziskovali rekristalizacijo in rast zrn v {irokem obmo~ju temperatur in deformacij. Rezultati raziskave so pokazali, da je proces rasti zrn novih ODS zlitin pomembno odvisen od termomehanske obdelave, ki vodi do maksimalne velikosti zrn po 20 urnem`arjenju na 1200°C. Avtorji so za analize uporabili razli~ne metode, vklju~no z opti~no mikroskopijo. Klju~ne besede: rast zrn, z oksidi disperzijsko utrjene zlitine (ODS), jeklo, Fe-Al, Al2O3Materiali in tehnologije / Materials and technology 52 (2018) 4, 475-482 475

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Section: Test Group Amentioning

confidence: 99%

Using thermomechanical treatments to improve the grain growth of new-generation ODS alloys

Khalaj¹,

Jirková²,

Mašek³

et al. 2018

Mater. Tehnol.

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“…Hence, it is expected that the oxide dispersion will also improve the cyclic strength and stabilize the cyclic behaviour of F/M steels. The first assumption was confirmed by Kuběna et al with a cyclic stress level of almost double magnitude (also see Figure where the studied ODS steels as well as ODS F/M P91 show higher cyclic strength than the conventional non‐ODS version of P91; the tests on P91 versions (for more details about these materials see Straßberger et al and Führer and Aktaa 32 ) were performed on the same type of sample, using the same test set‐up). In contrast, the second presumption of cyclic softening as shown still persists in the present 9YWT‐MATISSE, ODS P91 and was previously also reported for ODS EUROFER, see Kuběna et al However, even though the studied ODS steels exhibit cyclic softening, it is significantly lower than that of the non‐ODS P91 (Figure ).…”

Section: Discussionmentioning

confidence: 62%

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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“…The chemical compositions of the ODS steel are shown in Table 1. Before welding, the ODS steel was processed by heat treatment (1050° for 1 h, air cooling and 800 ° for 1 h, air cooling), which was the most common and effective heat treatment process for martensitic steel [13,19]. Before heat treatment, the material is initially in the rolled state.…”

Section: Materials and Experimental Proceduresmentioning

confidence: 99%

Investigation on microstructure and tensile shear properties of 9Cr oxide dispersion strengthened steel resistance spot welded joint

Jia

Wei

2023

Science and Technology of Welding and Joining

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Resistance spot welding is employed to join the 9Cr oxide dispersion strengthened steel and the effects of different welding parameters are studied. Within the ranges of parameters used in this experiment, the failure load and energy increased from 4.3 kN, 1.0 J to 6.8 kN, 7.5 J as the welding current increased, while as the electrode force increased, the failure load and energy first decreased from 6.8 kN, 3.8 J to nearly 4 kN, 1.2 J, then remained stable. As the welding current exceeded 12.8 kA, the failure mode changed from pull out failure along the fusion line to the pull out failure along the fusion line partially and base metal partially. The welding current and electrode force strongly affect the mechanical properties and fracture mode of the joint.

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High temperature tensile properties of oxide dispersion strengthened T91 and their correlation with microstructural evolution

Cited by 15 publications

References 15 publications

Using thermomechanical treatments to improve the grain growth of new-generation ODS alloys

Using thermomechanical treatments to improve the grain growth of new-generation ODS alloys

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

Investigation on microstructure and tensile shear properties of 9Cr oxide dispersion strengthened steel resistance spot welded joint

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