Cyclic hardening and dynamic strain aging during low-cycle fatigue of Cr-Mo tempered martensitic steel at elevated temperatures

Wei, Wenlan; Feng, Yaorong; Han, Lihong; Zhang, Qunbing; Zhang, Jianxun

doi:10.1016/j.msea.2018.07.084

Cited by 28 publications

(13 citation statements)

References 32 publications

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“…Thus, the processes of dynamic strain aging in the fracture zone can be associated with local high density at dislocations in this region. [12] The formation of the UFG structure by ECAP in combination with additional requenching made it possible to increase the fatigue endurance limit by more than 50% from 475 to 735 MPa. The main structural features that made it possible to ensure such a level of properties were a homogeneous UFG structure with an average grain size of 0.8 μm, smaller and uniformly distributed carbides of 30-50 nm, as well as an increased share of the CSL boundaries to 7%.…”

Section: Doi: 101002/adem202000034mentioning

confidence: 99%

“…Dynamic strain aging during fatigue tests can result from an increase in the diffusion coefficient of alloying elements due to an increase in the density of dislocations. Thus, the processes of dynamic strain aging in the fracture zone can be associated with local high density at dislocations in this region …”

Section: Parameters Of Microstructure From X‐ray Diffractionmentioning

confidence: 99%

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Microstructure and Fatigue of Ultrafine‐Grained Ferritic/Martensitic Steel

et al. 2020

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The impact of equal‐channel angular pressing in combination with additional heat treatment on microstructure and fatigue of ferritic/martensitic steel is investigated. It is shown that the formation of both the ultrafine‐grained (UFG) structure with an average grain size of about 0.8 μm and the enhanced share of boundaries with the coincidence site lattice (CSL) relationships (the CSL boundaries) leads to an increase in the fatigue endurance limit of more than 50% compared with samples after tempering. Dynamic strain aging is found in the fracture zone of the UFG of samples after fatigue tests. The influence of structural parameters on the fatigue endurance limit of the UFG samples is discussed.

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Section: Doi: 101002/adem202000034mentioning

confidence: 99%

Section: Parameters Of Microstructure From X‐ray Diffractionmentioning

confidence: 99%

Microstructure and Fatigue of Ultrafine‐Grained Ferritic/Martensitic Steel

et al. 2020

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“…The fracture analysis confirms that the second phase may cause the stress concentration and eventually affect the HCF properties. The crack nucleates near the carbides to form the main crack and the secondary crack [36]. Microvoids and secondary cracks absorbs energy during crack propagation, thereby reducing crack propagation rate.…”

Section: Tem Observation Before and After Hcfmentioning

confidence: 99%

High cycle fatigue behavior of a dissimilar metal welded joint in ultra-supercritical steam turbine rotor

Wang

Zhu

et al. 2020

Mater. Res. Express

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The high cycle fatigue (HCF) property and microstructure of a dissimilar metal welded joint (DMWJ) for ultra-supercritical steam turbine rotor were systematically investigated in this paper. The DMWJ was fabricated using narrow gap submerged arc welding (NG-SAW) technique with buttering layer. Conditional fatigue strength of 30Cr1Mo1V (BM-1), buttering layer (BL), weld metal (WM) and 30Cr2Ni4MoV (BM-2) based on S-N curve was obtained by HCF tests at room temperature. The microstructure and second-phase carbide as well as fracture appearance of BM-1, BL, WM and BM-2 were characterized by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscope (TEM). The results show that the BL has lower fatigue strength, which are related to more content of the soft ferrite and less content of the hard carbide. The acicular ferrite represents better fatigue properties than massive ferrite due to barrier effect. Additionally, dislocation density sharply increases near the carbides, grain boundaries, and lath structures resulting in dislocation tangle after HCF test, which helps to improve the fatigue strength of the welded joint. The carbide precipitated, aggregated, and grown in the grain boundaries promoted crack nucleation, reduced the crack propagation rate and affected the crack propagation path.

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“…With European policy aiming to reduce CO 2 emissions into the atmosphere, the Polish energy sector needs to adapt to European regulations. The reduction in CO 2 emissions can be achieved, among others, by increasing the operating parameters of supercritical boilers with constantly improved advanced materials which have better properties at elevated temperatures [1][2][3][4][5][6][7]. Such materials include the HR6W alloy, which is mainly used for superheater tubes in power boilers, thick-walled tubular elements, reactors, as well as in chemical plants.…”

Section: Introductionmentioning

confidence: 99%

Impact of Temperature on Low-Cycle Fatigue Characteristics of the HR6W Alloy

2021

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This paper presents the results of tests conducted on the HR6W (23Cr-45Ni-6W-Nb-Ti-B) alloy under low-cycle fatigue at room temperature and at 650 °C. Fatigue tests were carried out at constant values of the total strain ranges. The alloy under low-cycle fatigue showed cyclic strengthening both at room temperature and at 650 °C. The degree of HR6W strengthening described by coefficient n’ was higher at higher temperatures. At the same time, its fatigue life Nf at room temperature was, depending on the range of total strain adopted in the tests, several times higher than observed at 650 °C.

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Cyclic hardening and dynamic strain aging during low-cycle fatigue of Cr-Mo tempered martensitic steel at elevated temperatures

Cited by 28 publications

References 32 publications

Microstructure and Fatigue of Ultrafine‐Grained Ferritic/Martensitic Steel

Microstructure and Fatigue of Ultrafine‐Grained Ferritic/Martensitic Steel

High cycle fatigue behavior of a dissimilar metal welded joint in ultra-supercritical steam turbine rotor

Impact of Temperature on Low-Cycle Fatigue Characteristics of the HR6W Alloy

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