Aging phenomena during in-service creep exposure of heat-resistant steels

Grigorios Chaidemenopoulos; K. Polychronopoulou; A. D. Zervaki; H. Kamoutsi; S. I. Alkhoori; S. Jaffar; P. Cho; H. Mavros

doi:10.3390/met9070800

Aging phenomena during in-service creep exposure of heat-resistant steels

Grigorios Chaidemenopoulos, K. Polychronopoulou, A. D. Zervaki, H. Kamoutsi, S. I. Alkhoori, S. Jaffar, P. Cho, H. Mavros

Mechanical & Nuclear Engineering

University of Thessaly

Research output: Contribution to journal › Article › peer-review

11 Scopus citations

Abstract

An investigation of aging phenomena during creep exposure has been conducted for HP-Nb cast reformer tubes for several exposure conditions. Aging was manifested by carbide precipitation, carbide coarsening, and carbide transformation. The transformation of primary M₇C₃ to the more stable M₂₃C₆ carbide takes place at high exposure temperature (910 °C and above). The primary MC carbides transform to the Ni-Nb silicide or G-phase during creep exposure. The presence of Ti in the steel prevented the transformation of MC carbides to the G-phase. Morphological changes like needle to globular transitions, rounding of carbide edges, and carbide coarsening take place during creep exposure. The room-temperature tensile elongation and ultimate tensile strength are significantly reduced during creep exposure. The above aging phenomena are precursors to creep damage.

Original language	British English
Article number	800
Journal	Metals
Volume	9
Issue number	7
DOIs	https://doi.org/10.3390/met9070800
State	Published - Jul 2019

Keywords

aging
carbides
cast reformer tubes
creep
G-phase
steam reforming

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10.3390/met9070800

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title = "Aging phenomena during in-service creep exposure of heat-resistant steels",

abstract = "An investigation of aging phenomena during creep exposure has been conducted for HP-Nb cast reformer tubes for several exposure conditions. Aging was manifested by carbide precipitation, carbide coarsening, and carbide transformation. The transformation of primary M7C3 to the more stable M23C6 carbide takes place at high exposure temperature (910 °C and above). The primary MC carbides transform to the Ni-Nb silicide or G-phase during creep exposure. The presence of Ti in the steel prevented the transformation of MC carbides to the G-phase. Morphological changes like needle to globular transitions, rounding of carbide edges, and carbide coarsening take place during creep exposure. The room-temperature tensile elongation and ultimate tensile strength are significantly reduced during creep exposure. The above aging phenomena are precursors to creep damage.",

keywords = "aging, carbides, cast reformer tubes, creep, G-phase, steam reforming",

author = "Grigorios Chaidemenopoulos and K. Polychronopoulou and Zervaki, {A. D.} and H. Kamoutsi and Alkhoori, {S. I.} and S. Jaffar and P. Cho and H. Mavros",

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year = "2019",

month = jul,

doi = "10.3390/met9070800",

language = "British English",

volume = "9",

journal = "Metals",

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T1 - Aging phenomena during in-service creep exposure of heat-resistant steels

AU - Chaidemenopoulos, Grigorios

AU - Polychronopoulou, K.

AU - Zervaki, A. D.

AU - Kamoutsi, H.

AU - Alkhoori, S. I.

AU - Jaffar, S.

AU - Cho, P.

AU - Mavros, H.

PY - 2019/7

Y1 - 2019/7

N2 - An investigation of aging phenomena during creep exposure has been conducted for HP-Nb cast reformer tubes for several exposure conditions. Aging was manifested by carbide precipitation, carbide coarsening, and carbide transformation. The transformation of primary M7C3 to the more stable M23C6 carbide takes place at high exposure temperature (910 °C and above). The primary MC carbides transform to the Ni-Nb silicide or G-phase during creep exposure. The presence of Ti in the steel prevented the transformation of MC carbides to the G-phase. Morphological changes like needle to globular transitions, rounding of carbide edges, and carbide coarsening take place during creep exposure. The room-temperature tensile elongation and ultimate tensile strength are significantly reduced during creep exposure. The above aging phenomena are precursors to creep damage.

AB - An investigation of aging phenomena during creep exposure has been conducted for HP-Nb cast reformer tubes for several exposure conditions. Aging was manifested by carbide precipitation, carbide coarsening, and carbide transformation. The transformation of primary M7C3 to the more stable M23C6 carbide takes place at high exposure temperature (910 °C and above). The primary MC carbides transform to the Ni-Nb silicide or G-phase during creep exposure. The presence of Ti in the steel prevented the transformation of MC carbides to the G-phase. Morphological changes like needle to globular transitions, rounding of carbide edges, and carbide coarsening take place during creep exposure. The room-temperature tensile elongation and ultimate tensile strength are significantly reduced during creep exposure. The above aging phenomena are precursors to creep damage.

KW - aging

KW - carbides

KW - cast reformer tubes

KW - creep

KW - G-phase

KW - steam reforming

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DO - 10.3390/met9070800

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SN - 2075-4701

VL - 9

JO - Metals

JF - Metals

IS - 7

M1 - 800

ER -

Aging phenomena during in-service creep exposure of heat-resistant steels

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Keywords

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