Stress-Induced Variant Selection of γ″ Phase in Inconel 718 During Service: Mechanism and Effects on Mechanical Behavior

Qin, Hailong; Bi, Zhongnan; Zhang, Ruiyao; Lee, Tung Lik; Yu, Hongying; Chi, Hai; Li, Dongfeng; Dong, Hongbiao; Du, Jinhui; Zhang, Ji

doi:10.1007/978-3-030-51834-9_69

Cited by 4 publications

(4 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This compact coprecipitate microstructure is desirable because the compact morphology exhibits superior thermal stability [8,24]. While isolated γ precipitates and non-compact coprecipitates exhibit significant stress-assisted coarsening, compact coprecipitates show negligible coarsening under stress [25][26][27][28]. In fact, the compact coprecipitates have been shown to resist coarsening more than a thousand hours at 1200 • F (649 • C) [24].…”

Section: Discussionmentioning

confidence: 99%

Creep Behavior of Compact γ′-γ″ Coprecipitation Strengthened IN718-Variant Superalloy

Mukopadhyay

Sriram

Zenk

et al. 2021

Metals

View full text Add to dashboard Cite

The development of high-temperature heavy-duty turbine disk materials is critical for improving the overall efficiency of combined cycle power plants. An alloy development strategy to this end involves superalloys strengthened by ‘compact’ γ′-γ″ coprecipitates. Compact morphology of coprecipitates consists of a cuboidal γ′ precipitate such that γ″ discs coat its six {001} faces. The present work is an attempt to investigate the microstructure and creep behavior of a fully aged alloy exhibiting compact coprecipitates. We conducted heat treatments, detailed microstructural characterization, and creep testing at 1200 °F (649 °C) on an IN718-variant alloy. Our results indicate that aged IN718-27 samples exhibit a relatively uniform distribution of compact coprecipitates, irrespective of the cooling rate. However, the alloy ruptured at low strains during creep tests at 1200 °F (649 °C). At 100 ksi (689 MPa) load, the alloy fails around 0.1% strain, and 75 ksi (517 MPa) loading causes rupture at 0.3% strain. We also report extensive intergranular failure in all the tested samples, which is attributed to cracking along grain boundary precipitates. The results suggest that while the compact coprecipitates are indeed thermally stable during thermomechanical processing, the microstructure of the alloy needs to be optimized for better creep strength and rupture life.

show abstract

Section: Discussionmentioning

confidence: 99%

Creep Behavior of Compact γ′-γ″ Coprecipitation Strengthened IN718-Variant Superalloy

Mukopadhyay

Sriram

Zenk

et al. 2021

Metals

View full text Add to dashboard Cite

show abstract

“…3(d, h), in which a very small portion of the residual variants can be found. In fact, the degree of variant selection is a function of ageing temperature, ageing time, stress applied, and grain orientation [16]. Therefore, the is probably slightly larger than 1/2 for the TA sample and smaller than 1 for the CA one.…”

Section:  Variant-sensitive Strengtheningmentioning

confidence: 99%

“…Although these investigations show inconsistency in the observed deformation mechanisms, clearly, they all suggest that the deformation mechanism is variant dependent. Indeed, recent studies have shown that the mechanical property of IN718 can be enhanced by tailoring the γ'' variant distribution [15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%