Microstructural evolution in damaged IN738LC alloy during various steps of rejuvenation heat treatments

Hosseini, Sayyed Shahabeddin; Nategh, S.; Ekrami, A.

doi:10.1016/j.jallcom.2011.09.094

Cited by 38 publications

(12 citation statements)

References 24 publications

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“…There are other types of carbides such as M 6 C, where M denotes Si, Ni and Cr, and also M 23 C 6 where M denotes mainly Cr and/or Mo. [6][7][8][9] Nevertheless, the high cost of nickel based superalloys makes them unviable for massive applications in some situations. In order to overcome this obstacle and make the use of Ni-based alloys attractive to equipment manufacturers, providing high service performance using this particular class of material, overlays with Ni-based alloys on C-Mn low alloy and stainless steels have become an option in recent years.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Microstructural Characterization of Aged Nickel-based Alloy 625 Weld Metal

Silva

Albuquerque

Miná

et al. 2018

Metall Mater Trans A

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The aim of this work was to evaluate the different phases formed during solidification and after thermal aging of the as-welded 625 nickel-based alloy, as well as the influence of microstructural changes on the mechanical properties. The experiments addressed aging temperatures of 650 and 950 o C for 10, 100 and 200 h. The samples were analyzed by electron microscopy, microanalysis and X-ray diffraction in order to identify the secondary phases. Mechanical tests such as hardness, microhardness and Charpy-V impact test were performed. Nondestructive ultrasonic inspection was also conducted to correlate the signals with mechanical and microstructural properties. The results show that the alloy 625 when aged at 650 °C experienced microstructural changes that were responsible by the dissolution of Laves phase formed during the solidification and the appearance of fine carbides along the solidification grain boundaries. When aged at 950°C, the Laves phase was continuously dissolved and the excess Nb caused the precipitation of -phase (Ni 3 Nb), which was intensified at 10 hours of aging, with subsequent dissolution for longer periods such as 200 h. Even when subjected to significant microstructural changes, the mechanical properties, especially toughness, were not sensitive to the dissolution and/or precipitation of the secondary phases.

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Section: Introductionmentioning

confidence: 99%

Mechanical Properties and Microstructural Characterization of Aged Nickel-based Alloy 625 Weld Metal

Silva

Albuquerque

Miná

et al. 2018

Metall Mater Trans A

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“…[1][2][3] In order to obtain much more excellent resistance to primary water stress corrosion cracking in the nuclear power industry, steam generator and pressurised water reactor systems, nickel base alloys with high chromium were developed. 4,5 However, unfortunately, as confirmed by industry experience and laboratory investigation, the high chromium nickel base alloys were susceptible to hot cracking during welding.…”

Section: Introductionmentioning

confidence: 99%

Solidification behaviour of a high chromium nickel base alloy weld deposited metal

Chen

2015

Science and Technology of Welding and Joining

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The solidification behaviour including microsegregation and secondary phase formation of a high chromium nickel base alloy weld deposited metal was examined with optical microscopy, scanning electron microscopy and transmission electron microscopy. Microsegregation potential of major alloying elements in the weld deposited metal was investigated. The microconstituents formed during solidification were identified to be TiC and c/Laves eutectic constituent. Most c/ Laves eutectic constituents were located at the dendrite interstices due to the microsegregation of Nb, Mo and Si. The volume percent of c/Laves constituent was predicted by using Scheil equation, and there was a reasonable agreement between the predicted and measured value. Last, two possible solidification paths added to the c-Nb-C pseudoternary solidification diagram were proposed to analyse the solidification sequence of the new high chromium nickel base alloy.

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“…The solution heat treatments are designed to dissolve γ'/γ eutectic, γ' and carbide phases and allow the optimum reprecipitation of these phases upon cooling or after ageing. According to Table 2, four different heat treatment cycles including aging (A) [11], partial (B) [12], full (C) [4], and partial + full (D) [13] solution treatments followed by aging at 900° C for 10h were applied to the as-cast alloy. Metallographic sections were prepared using standard polishing procedures according to ASTM E3-01.…”

Section: Methodsmentioning

confidence: 99%

The effects of solution treatment on the microstructure of the cast Ni-based IN100 superalloy

Jafari¹,

Abbasi²,

Rahimi³

et al. 2015

Metall Mater Eng

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In this research, the effects of the partial, full and partial + full solution heat treatments followed by aging at 900° C for 10 h, on the microstructure of cast Ni-based IN100 superalloy were assessed. It has been found that, the alloy in the partial + full solution treated condition had the optimal combination of γ' morphology, volume fraction and size. In this condition, the alloy possesses a cubic primary γ'with an average size of 470±10nm and 45% volume fraction. Discrete M 23 C 6 and M 6 C carbides were formed at the grain boundaries and the morphology of the cubic MC carbide was changed to the spherical shape. In addition, the volume fraction of γ'/γ eutectic phase dropped to half of its value, compared to the as-cast alloy. During partial solution treatment followed by aging, discrete carbides were formed at the grain boundaries. This treatment without full solutioning was not an effective method to provide an optimal volume fraction and arrangement of γ' and MC carbides morphology. Full solutioning alone, changed the cubic morphology of the primary γ' and the blocky MC carbides to the spherical shape.

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Microstructural evolution in damaged IN738LC alloy during various steps of rejuvenation heat treatments

Cited by 38 publications

References 24 publications

Mechanical Properties and Microstructural Characterization of Aged Nickel-based Alloy 625 Weld Metal

Mechanical Properties and Microstructural Characterization of Aged Nickel-based Alloy 625 Weld Metal

Solidification behaviour of a high chromium nickel base alloy weld deposited metal

The effects of solution treatment on the microstructure of the cast Ni-based IN100 superalloy

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