Carburization and oxidation

Grabke, H. J.; Wolf, Irene

doi:10.1016/0025-5416(87)90357-0

Cited by 102 publications

(36 citation statements)

References 29 publications

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“…The carburization zone in the Fe-Ni-Cr alloy generally consisted of Cr 7 C 3 in the exterior and Cr 23 C 6 in the interior according to both cross-sectional micrographs and XRD results (Table II), which is consistent with other investigations. 1,4,21 In contrast, carburization was much more rapid at 1050°C. As shown in Fig.…”

Section: Materials Characterizationmentioning

confidence: 87%

“…Recently, Klo¨wer et al 6 reported that 602CA Ni-Cr-2.3 wt%Al alloy showed extremely low carbon uptake at 1100°C for 1000 h in CH 4 -H 2 . Unfortunately, an addition of Al or Si more than 2 wt% undermines the ductility and weldability of the alloys, 10 while 4 wt% Al (or Si) is typically required to form an external scale 1,3,9 Other alloying elements such as Mo, Mg, Nb, Ti, and reactive elements are reported to improve the carburization resistance of alloys to some extent. 6,[10][11][12] Surface-engineered coating is a feasible solution to the carburization problem.…”

Section: Introductionmentioning

confidence: 99%

“…It refers to the ingress of carbon and the precipitation of carbides when the alloys are used at 800-1100°C in carburizing atmospheres with low carbon activities (a c £ 1). [1][2][3][4][5] Excessive carbides in alloys cause a volume increase and significant internal stresses, which may induce premature failure of the alloys. 2 Brittle carbides also deteriorate the room-temperature ductility of alloys.…”

Section: Introductionmentioning

confidence: 99%

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Carburization Behavior of Electrodeposited Ni3 Al–CeO2-Base Coatings on Fe–Ni–Cr Alloys

Liu

Chen

2007

Oxid Met

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The cyclic carburization of electrodeposited pure and CeO 2 -dispersed Ni 3 Al intermetallic coatings on Fe-Ni-Cr alloys has been investigated at 850 and 1050°C for periods up to 500 h in a reducing 2%CH 4 -H 2 atmosphere. At 850°C, all Ni 3 Al-base-coating samples showed excellent carburization resistance and slow mass increases due to the formation of a thin c-Al 2 O 3 scale and a low carbon activity (a c = 0.73). At 1050°C and a high carbon activity (a c = 3.21), all coatings are superior to the uncoated Fe-Ni-Cr alloy in terms of carburization resistance. A thin a-Al 2 O 3 scale slowly formed on all Ni 3 Al coatings effectively blocked the carbon attack. The addition of CeO 2 particles in the Ni 3 Al coatings significantly mitigated the cracking of the a-Al 2 O 3 scale and the resultant internal oxidation and carburization. For all coatings, Ni-rich particles were found to be formed on the a-Al 2 O 3 scale during oxidation, which had led to the deposition of catalytic coke.

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Section: Materials Characterizationmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Carburization Behavior of Electrodeposited Ni3 Al–CeO2-Base Coatings on Fe–Ni–Cr Alloys

Liu

Chen

2007

Oxid Met

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“…The composition of the M 7 C 3 depends on the local carbon activity [16,17], and thus, in the ex-service tube, on the distance from the inner diameter. The main metal component of M 7 C 3 is Cr, but with increasing carbon activity an increased amount of iron is substituted for chromium [17][18][19].…”

Section: Chromium Carbidesmentioning

confidence: 99%

“…Kaya proposed that the excess elements (presumably Fe, Cr, and Ni [18], as M 7 C 3 has a lower ratio of M to C) that cannot be accommodated in the M 7 C 3 carbides upon the transformation from M 23 C 6 would form the austenite phase regions in the M 7 C 3 carbides, and that these austenite regions may nucleate on the M 23 C 6 /M 7 C 3 transformation front, or alternatively behind the moving front on the defects present in the M 7 C 3 carbides. EBSD analysis of 65 contained austenite-matrix pairs enabled the disorientation between the contained austenite regions and the adjacent austenitic matrix to be calculated.…”

Section: Chromium Carbidesmentioning

confidence: 99%

Microstructure and Carburization Detection in HP Alloy Pyrolysis Tubes

McLeod

Bishop

Stevens

et al. 2015

Metallogr. Microstruct. Anal.

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A highly carburized HP40-Mod alloy ethylene pyrolysis tube was characterized by means of scanning electron microscopy with backscatter electron imaging, electron back-scattered diffraction, energy dispersive spectroscopy, and etching using the NACE International Standard Test Method for evaluation of carburization of ethylene pyrolysis tubes. The response of the tube to eddy current non-destructive testing was measured using the carburization crawler under development at Quest Integrity NZL Ltd. The matrix was significantly depleted of chromium, as low as 4 wt% Cr at the inner wall. M 23 C 6 carbides transformed to M 7 C 3 at the inner wall region and NbC carbides partially transformed to the chromium-rich g-carbide at the outer wall region, both of which likely contributed to the chromium depletion of the matrix. The present results indicate that the NACE etchant attacks the austenitic matrix where chromium content is below approximately 12wt%. A comparison to other ex-service tubes indicates that matrix chromium content and the location of the M 23 C 6 /M 7 C 3 transformation front are useful microstructural characteristics for interpreting eddy current NDT response.

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