Effects of Microstructure on Eddy Current Residual Stress Characterization of Shot-Peened Inconel 718

Chandrasekar, Ramya; Frishman, Anatoli M.; Larson, Brian; Lo, C. C. H.; Nakagawa, N.

doi:10.1007/s11837-012-0234-3

Cited by 16 publications

(19 citation statements)

References 13 publications

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“…4. The results clearly confirm that RR1000 exhibits the general monotonic trend between the hardness and the conductivity, as observed in the previous research works [4][5][6]. As mentioned earlier, the literature attributes the hardness influence of conductivity in nickel-based alloys on J'' and G phase precipitates.…”

Section: Electrical Conductivitysupporting

confidence: 90%

“…2 and 3. A similar behavior of reduced conductivity was observed by Chandrasekar et al [5] with IN718 material due to the underaging heat treatment. This behavior was attributed to the possible formation of fine precipitates which resulted in the increased electron scattering and the reduced conductivity.…”

Section: Electrical Conductivitysupporting

confidence: 85%

“…A significant correlation between bulk conductivity (measured as AECC, Apparent Eddy Current Conductivity) and hardness of the material is observed as both AECC and hardness increased monotonically with an increase in time and temperature of thermal aging. A similar behavior was observed by Chandrasekar et al [5], where the linear relationship between hardness and conductivity of heat-treated IN718 prevailed. In a recent study, Pereira et al [6] compared the hardness and the conductivity of IN718 with the lattice constant to examine the underlying mechanisms.…”

Section: Introductionsupporting

confidence: 87%

“…In a recent study, Pereira et al [6] compared the hardness and the conductivity of IN718 with the lattice constant to examine the underlying mechanisms. It is consistently concluded from these research works [4][5][6] that the electrical conductivity of the material is influenced significantly by the evolution of precipitates during thermal aging. Formation and subsequent coarsening of J'' precipitates removes solute atoms from the matrix, causing a reduction in electron scattering and an increase in conductivity.…”

Section: Introductionmentioning

confidence: 70%

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Influence of Heat Treatment on the Conductivity of Nickel-Based Superalloys

Castagne

Annamalai

Zheng

et al. 2015

MATEC Web of Conferences

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Abstract. Non-destructive measurement of residual stress at the subsurface of nickel-based alloys using eddy current method has been limited by its sensitivity to its microstructure, especially to the precipitates. This paper investigates the effect of heat treatment on the electrical conductivity of RR1000, a nickel-based superalloy with a large fraction of J' precipitates. Different heat treatment conditions, ranging from solution heat treatment to precipitation hardening with different aging times and temperatures, are used to achieve varying initial microstructures. Hardness of the samples is measured first to quantify the heat treated samples followed by the measurement of electrical conductivity using the conductivity probes of frequencies between 1 MHz and 5 MHz. The relationship between the hardness and conductivity of the heat treated samples is then correlated further. The results highlight the significant influence of heat treatment on the sample hardness and the electrical conductivity of RR1000.

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Section: Electrical Conductivitysupporting

confidence: 90%

Section: Electrical Conductivitysupporting

confidence: 85%

Section: Introductionsupporting

confidence: 87%

Section: Introductionmentioning

confidence: 70%

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Influence of Heat Treatment on the Conductivity of Nickel-Based Superalloys

Castagne

Annamalai

Zheng

et al. 2015

MATEC Web of Conferences

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“…Despite the significant potential of EC, several challenges have been identified against development of the measurement technique for residual stress characterization. In particular, it has been found in recent studies that the EC responses of Inconel 718 to shot peening depend on the underlying microstructures [5][6][7][8]. These findings indicate the confounding effects of metallurgical factors on EC residual stress measurements, and raised doubts about the applicability of the empirical piezoresistivity relationship to shotpeened surfaces without modification or compensation for the competing effects of peening-induced changes in the material conditions.…”

Section: Introductionmentioning

confidence: 99%

Effects of cold work on near-surface conductivity profiles in laser shock peened and shot peened nickel-base superalloy

Lesthaeghe¹,

Larson²,

Chandrasekar³

et al. 2013

AIP Conference Proceedings

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This paper reports on a study of the effects of cold work induced by surface enhancement treatment on conductivity profiles in nickel-base superalloys, as part of the on-going efforts aimed at evaluating the feasibility of characterizing near-surface residual stress profiles in peened engine components using a swept frequency eddy current (SFEC) technique. The approach is based on the empirical piezoresistivity effect that correlates conductivity changes with residual stress, but recent studies have shown that conductivity changes induced by peening processes are also influenced by metallurgical factors such as cold work. In this study, conductivity deviation profiles were obtained by model-based inversion of SFEC signals from a set of aged Inconel 718 samples, which were either shot peened or laser shock peened to produce different residual stress and cold work profiles. The laser shock peened samples exhibit a larger increase in surface conductivity and deeper conductivity profiles, which are attributed to a smaller amount of surface cold work and deeper residual stress profiles created by laser shock peening than by shot peening. ABSTRACT. This paper reports on a study of the effects of cold work induced by surface enhancement treatment on conductivity profiles in nickel-base superalloys, as part of the on-going efforts aimed at evaluating the feasibility of characterizing near-surface residual stress profiles in peened engine components using a swept frequency eddy current (SFEC) technique. The approach is based on the empirical piezoresistivity effect that correlates conductivity changes with residual stress, but recent studies have shown that conductivity changes induced by peening processes are also influenced by metallurgical factors such as cold work. In this study, conductivity deviation profiles were obtained by model-based inversion of SFEC signals from a set of aged Inconel 718 samples, which were either shot peened or laser shock peened to produce different residual stress and cold work profiles. The laser shock peened samples exhibit a larger increase in surface conductivity and deeper conductivity profiles, which are attributed to a smaller amount of surface cold work and deeper residual stress profiles created by laser shock peening than by shot peening.

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