Effect of Long Range Order on the Stress Corrosion Susceptibility of a Nickel-33 at% Chromium Alloy

Young, George A.; Morton, David Alexander Vodden; Lewis, N.; Morris, Robert; Pyle, Joseph M.; Barnard, Leland; Najafabadi, R.

doi:10.5006/2200

Cited by 16 publications

(11 citation statements)

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“…Given that model alloys tend to develop LRO readily (see for example ref. [3]), a piece of model alloy with demonstrated LRO history [20] was obtained for this program from one of the authors, Dr. S.S. Kim of KAERI, Korea. The Ni-33Cr plate was made by vacuum induction melting followed by hot rolling at 1200C, solution annealing at 1050C for 1 h and water quenching.…”

Section: Model Ni-33cr Alloymentioning

confidence: 99%

“…The Ni-33Cr plate was made by vacuum induction melting followed by hot rolling at 1200C, solution annealing at 1050C for 1 h and water quenching. At ANL, this solutionannealed alloy was subjected to two different aging treatments at 475C known to induce LRO [3]. The intent is to use these conditions as reference for the material characterization effort undertaken in this program which involves commercial heats.…”

Section: Model Ni-33cr Alloymentioning

confidence: 99%

“…Model alloy Ni-33Cr was aged for 2,000h at 475ºC (LRO confirmed to occur) 2 Alloy 690 aged for 2,000h at 475ºC (commercial companion for the model alloy) 3 GBE = Grain Boundary Engineered; both conditions of this heat were SCC-tested previously Figure 14 shows the Diffraction pattern from the model Ni-33C aged for at 475C for 2000h. The superlattice reflections (green arrow) confirm the presence of LRO.…”

Section: Tem Of Irradiated Alloy 690 Specimensmentioning

confidence: 99%

“…formation of the intermetallic Ni2Cr phase which can lead to in-service embrittlement of Ni-Cr components. Research with binary Ni-Cr binary alloys by Young et al [3] have found that LRO promotes SCC, with an SCC CGR 1,000x larger than the non-ordered version of the alloy. However, Fe plays a key role in ordering, and it is not clear at this time whether LRO occurs in commercial heats as the addition of Fe was found to hinder LRO formation [4].…”

Section: Introductionmentioning

confidence: 99%

“…As noted previously, with the notable exception of the study by Young et. al [3] on model alloy Ni-33Cr, the effects of those microstructural changes on the SCC response have not been evaluated.…”

Section: Introductionmentioning

confidence: 99%

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Effect of thermal aging and irradiation on microstructure and crack growth response of Alloy 690

Alexandreanu¹,

Chen²,

Zhang³

et al. 2021

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Nickel-base Alloy 690 and the associated weld Alloys 52 and 152 are typically used for nozzle penetrations in replacement heads for pressurized water reactor (PWR) vessels, because of their excellent overall resistance to general corrosion and environmental degradation, primarily stress corrosion cracking (SCC). However, many of the existing PWRs reactors are expected to operate for 40-80 years. Likewise, advanced water-cooled small modular reactors (SMRs) will use Ni-Cr alloys and are expected to receive initial operating licenses for 60 years. Hence, the thermal stability of Ni-Cr alloys is a potential concern for the long-term performance of both existing and advanced nuclear plants, and possibly spent fuel storage containers. The objective of this research is to understand the microstructural changes occurring in high-Cr, Ni-based Alloy 690 during long time exposure to the reactor operating temperatures, and the effect of these changes on the service performance. One area of particular concern is the potential for long range ordering (LRO), i.e. formation of the intermetallic Ni2Cr phase under prolonged exposure to reactor temperatures and/or irradiation, which can increase strength, decrease ductility, and cause dimensional changes or lead to in-service embrittlement of components made with these alloys. Hence, this research focused on the microstructural evolution and the SCC response of Alloy 690 under accelerated thermal aging and irradiation conditions. The materials studied involved Alloy 690 from two sources: (i) Alloy 690 plate from an Alloy 152 dissimilar metal weld (DMW) joining the Alloy 690 plate to Alloy 533 LAS, aged at three different temperatures (370C, 400C and 450C) for up to 75,000h (equivalent to 60 years of service), and (ii) specimens neutron-irradiated in the BOR-60 reactor up to 40 dpa. For aged Alloy 690 specimens, hardness was found to increase with aging time, however, the microstructural characterization by means of synchrotron X-ray did not find evidence of LRO. The microstructural characterization of neutron-irradiated specimens by TEM found no evidence of LRO either. Testing in a primary water environment of Alloy 690 specimens aged to a 60year service equivalent revealed a fatigue and corrosion fatigue crack growth responses similar to those measured on the un-aged alloy. The SCC CGR response was also low. Overall, the two Alloy 690 heats investigated in this work, aged up to 60-year service equivalents or exposed to neutron irradiation up to 40 dpa, did not exhibit a deterioration in microstructure or performance.

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Section: Model Ni-33cr Alloymentioning

confidence: 99%

Section: Model Ni-33cr Alloymentioning

confidence: 99%

Section: Tem Of Irradiated Alloy 690 Specimensmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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