Rejuvenation of service exposed ammonia cracker tubes of cast Alloy 625 and their re-use

Singh, J.B.; Verma, Amit Kumar; Jaiswal, Dheeraj; Kumar, Niraj; Patel, Ritesh; Chakravartty, J.K.

doi:10.1016/j.msea.2015.06.098

Cited by 17 publications

(3 citation statements)

References 18 publications

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“…The normal form of the δ phase generally nucleates at grain boundaries, but at relatively high temperatures (850-900 • C) also forms in an intragranular fashion [19,23]. However, studies on the δ phase precipitation in cast alloy IN625 are scarce [24]. Moreover, increasing the Nb concentration is found to increase the driving force to form the δ phase [25], so it is excepted the fraction of the δ phase can be controlled by changing the Nb content.…”

Section: Introductionmentioning

confidence: 99%

Effect of Nb on δ Phase Precipitation and the Tensile Properties in Cast Alloy IN625

Wang²,

Zhou

et al. 2018

Metals

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Cast alloy IN625 is a candidate Ni-base alloy for advanced ultra-supercritical (A-USC) power plants. The aim of this study was to investigate the influences of Nb on δ phase precipitation and the tensile properties in this alloy. The results show that the δ phase is easy to precipitate after long-term aging at 700 • C (the service temperature of A-USC power plants) and it is strongly affected by the content of Nb in the alloy. The strength of alloys after aging at 700 • C for 10,000 h increases with the increasing Nb content and also increases sharply when compared to that of as-heat-treated alloys. The increase in strength is found to be primarily associated with the precipitation of the δ phase.

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Section: Introductionmentioning

confidence: 99%

Effect of Nb on δ Phase Precipitation and the Tensile Properties in Cast Alloy IN625

Wang²,

Zhou

et al. 2018

Metals

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“…Inconel 625 alloy is extensively used to manufacture ammonia cracker tubes in heavy water production plants owing to its excellent strength and creep resistance, good resistance to oxidation, corrosion, and hydrogen attack, excellent formability, and low hydrogen permeability at both ambient and elevated temperatures [1][2]. The severe service conditions of these tubes include high temperatures (600 °C), high pressures (14 MPa), and prolonged usage periods (~60,000 h), which lead to a significant increase in strength but loss of ductility and toughness that may subsequently result in premature failure [3][4]. Inconel 625 is a solid-solute-strengthened alloy created by adding Mo and Nb to a Ni-Cr-based matrix [5].…”

Section: Introductionmentioning

confidence: 99%

Grain-size dependent elastic-plastic deformation behaviour of inconel 625 alloy studied by in-situ neutron diffraction

Gao

Ding

et al. 2021

Intermetallics

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“…Based on the influence of phase transformation that can occur in the microstructure of the Inconel 625 superalloy at different conditions of heat-treatment and the scarce of studies on the δ phase precipitation in the microstructure of Inconel 625 superalloy 15 , the aim of this work is to evaluate the microstructural changes in the solutioned and aged samples of Inconel 625 superalloy at different conditions of time and temperature with special focus on the analysis of δ-phase precipitation. *e-mail: renatobaldan@gmail.com.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Delta Phase Precipitation in Inconel 625 Superalloy Aged at 550, 625 and 725 °C

et al. 2020

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The δ is an important stable phase that replaces the metastable γ'' in the microstructure of Inconel 625 superalloy. The present work aims to investigate the kinetic of δ-phase precipitation in the microstructure of Inconel 625 nickel-based superalloy aged at 550, 625 and 725 °C up to 1000 h. Aging temperatures were chosen based on the thermodynamic simulation using JMatPro software which indicated that this phase is stable at temperatures below 905 °C. Microstructure of the heat-treated samples was analyzed via SEM/EDS and microhardness evolution was performed by Vickers microhardness tests. The results have shown that the samples aged at 550 °C (all times), 625 °C (all times) and 725 °C up to 200 h did not presented microstructural evidences of δ precipitation. However, samples aged at 725 °C for 500 and 1000 h clearly presented an acicular δ-phase precipitated mainly at the grain boundaries. It was noted changes in the microhardness at different aging time and temperatures probably due to the presence of γ'' and/or δ phases. The sample aged at 625 °C for 1000 h presented the highest microhardness value (333 ± 10 HV).

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Rejuvenation of service exposed ammonia cracker tubes of cast Alloy 625 and their re-use

Cited by 17 publications

References 18 publications

Effect of Nb on δ Phase Precipitation and the Tensile Properties in Cast Alloy IN625

Effect of Nb on δ Phase Precipitation and the Tensile Properties in Cast Alloy IN625

Grain-size dependent elastic-plastic deformation behaviour of inconel 625 alloy studied by in-situ neutron diffraction

Experimental Investigation of Delta Phase Precipitation in Inconel 625 Superalloy Aged at 550, 625 and 725 °C

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