Damage tolerance of wrought alloy 718 Ni- Fe-base superalloy

Chang, M.; Koul, A. K.; Au, P.; Terada, T.

doi:10.1007/bf02645332

Cited by 18 publications

(6 citation statements)

References 14 publications

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“…According to the different factors affecting the low-cycle fatigue performance, the influence of microstructure on the low-cycle fatigue life of notch [21] and hot forged alloys [22], the influence of delta phase content [23] and thermal corrosion [24] on low-cycle fatigue behavior, and the influence of frequency and waveform on fatigue crack propagation rate [25] have been studied. Nowadays, the damage tolerance is increasingly applied to turbine blades, Citarella et al [26,27] have shown that even with a crack, the blade might avoid replacement if accurate propagation of crack could validate such a maintenance choice, and Chang et al [28] studied the influence of solid-solution temperature on damage tolerance.…”

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confidence: 99%

High Cycle Fatigue Performance of Inconel 718 Alloys with Different Strengths at Room Temperature

Liqiong

Liang

et al. 2018

Metals

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In this paper, the high cycle fatigue performance of solid solution state and aged Inconel 718 superalloys was studied at room temperature. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze the original structural features and fatigue deformation features of two kinds of alloys. SEM, laser scanning confocal microscopy, and electron backscatter diffraction (EBSD) were used to analyze the secondary fracture features of the fatigue fracture morphology and fatigue fracture profile. The results showed that the aging treatment significantly affected the strength and plasticity of the alloy, which in turn affected the fatigue performance of the alloy. After the aging treatment, the yield strength σ s and the tensile strength σ b of the Inconel 718 alloy increased by 152% and 65.9%, respectively, compared with those of the solid solution state, but the rate of elongation δ and rate of contraction in the cross-section area ϕ decreased by 63.7% and 52.3%, respectively. The fatigue limit of the aged state was lower than that of the solid solution state by 6.3%. The quadratic function relationship between the high cycle fatigue limit σ −1 and the tensile strength σ b of the Inconel 718 superalloy at room temperature was σ −1 = σ b · (0.869−3.67 × 10 −4 · σ b ). An analysis of the fatigue fracture mechanism showed that the fatigue fractures before and after aging were all initiated in the grains oriented relatively unfavorably on the surface of the sample, with a mixture of intergranular and transgranular propagation after the transgranular propagation of several grains. The higher plasticity of the solid solution state Inconel 718 alloy resulted in a large number of slip deformation zones under high cycle fatigue loads, and the plastic deformation was relatively uniform. The lengths of the secondary fractures were as high as 120 µm, which formed the single-source plastic fatigue fracture that promoted an increase in the fatigue limit. After aging treatment, the higher strength of the Inconel 718 alloy made dislocation slip difficult under high cycle fatigue loads, and the plasticity compatible deformation capability was poor. When local dislocations slipped to the intragranular γ" phase, γ' phase, or interfaces with nonmetallic compounds (NMCs), plugging occurred. The degree of stress concentration increased, causing the initiation of fatigue fracture; the secondary fracture was approximately 20 µm. Brittle cleavage due to multiple sources significantly reduced the fatigue limit.

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confidence: 99%

High Cycle Fatigue Performance of Inconel 718 Alloys with Different Strengths at Room Temperature

Liqiong

Liang

et al. 2018

Metals

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“…The results of the hardness measurements that were carried out on a strut with a 2 mm diameter are listed in Table 2. Each specimen volume probed revealed a direct aged condition, e.g., the hardness values found were similar to the hardness of conventionally manufactured IN718 after aging [28]. The hardness values in the different specimen areas did not significantly differ from each other, and, thus, despite the pronounced changes in geometry in the characterized specimen areas, homogeneous local mechanical properties were found.…”

Section: Resultsmentioning

confidence: 57%

“…The precipitations close to the specimen surface formed either on grain boundaries (shown in Figure 2b) or dispersedly throughout the grains, as is depicted in Figure 2c. aging [28]. The hardness values in the different specimen areas did not significantly differ from each other, and, thus, despite the pronounced changes in geometry in the characterized specimen areas, homogeneous local mechanical properties were found.…”

Section: Resultsmentioning

confidence: 79%

Damage Tolerance Evaluation of E-PBF-Manufactured Inconel 718 Strut Geometries by Advanced Characterization Techniques

et al. 2020

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By means of electron beam powder bed fusion (E-PBF), highly complex lightweight structures can be manufactured within short process times. Due to the increasing complexity of producible components and the entangled interplay of damage mechanisms, common bulk material properties such as ultimate tensile or fatigue strength are not sufficient to guarantee safe and reliable use in demanding applications. Within this work, the damage tolerance of E-PBF-manufactured Ni-based alloy Inconel 718 (IN 718) strut geometries under uniaxial cyclic loading was investigated supported by several advanced measurement techniques. Based on thermal and electrical measurements, the failure of single struts could reliably be detected, revealing that continuous monitoring is applicable for such complex geometries. Process-induced surface roughness was found to be the main reason for early failure during cyclic loading. Thus, adequate post-processing steps have to be established for complex geometries to significantly improve damage tolerance and, eventually, in-service properties.

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“…Serrated grain boundaries have been shown to have very beneficial effects on the creep properties o f various materials. In general, the creep rupture life and creep ductility is increased in materials with serrated grain boundaries as opposed to planar grain boundaries [22][23][24][25][26][27][28][29][30][31][32], This can be seen for 21-4N in Figure 32. Figure 35).…”

Section: Effects Of Serrated Grain Boundaries On Creepmentioning

confidence: 90%

“…Creep tests o f nickel base superalloy IN718 with serrated grain boundaries (solid line) and planar grain boundaries (broken line)[28].…”

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confidence: 99%

Effect of serrated grain boundaries on the creep of 21-4N manganese austenitic stainless steel

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Damage tolerance of wrought alloy 718 Ni- Fe-base superalloy

Cited by 18 publications

References 14 publications

High Cycle Fatigue Performance of Inconel 718 Alloys with Different Strengths at Room Temperature

High Cycle Fatigue Performance of Inconel 718 Alloys with Different Strengths at Room Temperature

Damage Tolerance Evaluation of E-PBF-Manufactured Inconel 718 Strut Geometries by Advanced Characterization Techniques

Effect of serrated grain boundaries on the creep of 21-4N manganese austenitic stainless steel

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