Characterisation of 20Cr32Ni1Nb alloys in as-cast and Ex-Service conditions by SEM, TEM and EDX

Chen, Qizhi; Thomas, Charles W.; Knowles, David

doi:10.1016/j.msea.2004.03.038

Cited by 40 publications

(22 citation statements)

References 11 publications

(13 reference statements)

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“…This is coincidence to others' work, which has reported the same orientation of the Cr 23 C 6 during aging at 760 o C [20] and 900 o C [5,16,24] , respectively. It can also be inferred that the precipitation orientation of carbide is not affected by the aging temperature.…”

Section: Cr32ni1nbsupporting

confidence: 91%

“…It has been extensively reported that the network chromium carbide develops at the grain boundary of HP40 and HK40 alloy, strengthening the alloy by inhibiting the grain boundary sliding during alloy deforming at elevated temperature [18,19] . By comparing, the Cr 23 C 6 carbide in the 20Cr32Ni1Nb alloy usually form during service, precipitating at both the grain interior and boundary in fewer amount [20] . The absence of chromium carbide in the cast 20Cr32Ni1Nb alloy is mainly because of the Nb/C ratio satisfies as below [21] :…”

Section: Introductionmentioning

confidence: 99%

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Effect of carbon on the microstructure evolution and mechanical properties of low Si-containing centrifugal casting 20Cr32Ni1Nb alloy

Yan

Dang

et al. 2016

Materials Chemistry and Physics

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The dendrite structure, which is formed during centrifugal casting process, plays an important role in the fracture behavior of 20Cr32Ni1Nb alloy. The large primary carbide facilitates the crack nucleation and propagation along the dendrite interface during high temperature deformation. The secondary NbC precipitates near the dendrite interface during aging at 1120 o C, while the major precipitates change to secondary Cr 23 C 6 when aging at lower temperature. These secondary carbides effectively strengthen the dendrite interface, which is probably due to inhibiting the crack propagation and decreasing the stress concentration. However, the benefit of the secondary carbide reduce when the precipitation free zone form aging at high temperature. Increasing C content enhances the precipitation tendency of Cr 23 C 6 , and facilitates the coalescing of the carbide at elevated temperature. As a result, the cracks can easily nucleate at the interface between NbC and Cr 23 C 6 , and then propagate along the large chromium carbide during deformation. However, the small chromium carbide precipitates form at lower aging temperature, and thus strengthens the alloy effectively.

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Section: Cr32ni1nbsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Effect of carbon on the microstructure evolution and mechanical properties of low Si-containing centrifugal casting 20Cr32Ni1Nb alloy

Yan

Dang

et al. 2016

Materials Chemistry and Physics

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“…It is clear that they were all primarily composed of fully austenitic matrix at the intra‐dendritic region and a network of eutectic structure at the interdendritic region. The eutectic structure consisted of austenite and primary Nb(C,N) that presented the white contrast in Figure b, d, and f, according to EDS analysis, thermal dynamic calculations, and published literatures . The morphology of the primary Nb(C,N) was “Chinese‐script” in alloys 1.4826 and 3C2N, while it was dispersed plate‐like and blocky in alloy 1W6C4N.…”

Section: Resultsmentioning

confidence: 78%

Low Cycle Fatigue Behavior of Heat‐Resistant Austenitic Cast Steels at 950 °C

Zhao

Engler-Pinto

et al. 2018

steel research int.

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Exhaust manifolds are frequently subjected to severe thermal cycling due to startup and shutdown of automobile engines; consequently, high‐temperature fatigue is the predominant failure mode for these components. The research about the relationship between high‐temperature fatigue properties and as‐cast microstructure in austenitic cast steels, which are the most popular materials for exhaust manifolds, is limited. In this study, strain‐controlled low cycle fatigue tests are conducted at 950 °C on two lab‐cast and one commercial‐cast austenitic cast steels with different morphology of primary Nb(C,N). The results indicate that decreasing the lamellar spacing of primary Nb(C,N) is an effective way to increase the LCF lifetime at the high strain range, hence the “Chinese‐script” primary Nb(C,N) is a more desirable morphology. The combination of cracking and prior oxidation of the dispersed plate‐like and blocky primary Nb(C,N) can result in the reduction of LCF lifetime. The influence of the primary Nb(C,N) morphology on the LCF lifetime is negligible at a low strain range, hence lowering the secondary dendrite arm spacing (SDAS) to less than 30 μm significantly extends the LCF lifetime of austenitic cast steels. Additionally, the plastic strain energy density is an effective parameter to predict the LCF lifetime at 950 °C in austenitic cast steels.

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“…As a high-temperature material, Cr-Ni austenitic steels are broadly used to make components for petrochemical, metal heat treatment and thermal power generating equipment [1][2][3][4][5][6][7][8]. For instance, a novel austenitic heat-resistant cast steel 35Cr25Ni12NNbRE was recently developed by the group and used to make the nozzle and transport chamber of pulverized coal burner for power station boiler.…”

Section: Introductionmentioning

confidence: 99%

“…The service life of the components made from the N, Nb and RE-containing heatresistant cast steel was found much longer than those made from the 316-type austenitic stainless steel and the HK40-type heatresistant steel. Long-term service at high temperature of austenitic stainless or heat-resistant steels can bring about decomposition of austenite and forming of carbides and intermetallic compounds such as sigma, chi, Laves, and epsilon phases [1,2,[5][6][7][8][9][10][11][12][13]. The crystallography of the carbides M 23 C 6 , M 6 C, and -Cr 2 N with the austenite or ferrite in the stainless or heat-resistant steels has been studied [6,7,[13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Microstructural evolution in austenitic heat-resistant cast steel 35Cr25Ni12NNbRE during long-term service

Liu

Jiao

Luo

2010

Materials Science and Engineering: A

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Characterisation of 20Cr32Ni1Nb alloys in as-cast and Ex-Service conditions by SEM, TEM and EDX

Cited by 40 publications

References 11 publications

Effect of carbon on the microstructure evolution and mechanical properties of low Si-containing centrifugal casting 20Cr32Ni1Nb alloy

Effect of carbon on the microstructure evolution and mechanical properties of low Si-containing centrifugal casting 20Cr32Ni1Nb alloy

Low Cycle Fatigue Behavior of Heat‐Resistant Austenitic Cast Steels at 950 °C

Microstructural evolution in austenitic heat-resistant cast steel 35Cr25Ni12NNbRE during long-term service

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