Ultrasonic quantification of high temperature cyclic damage in an advanced nickel based superalloy

Barat, K and Metya, A and Sathpathy, S and Sivaprasad, S and Tarafder, S and Kar, Sujoy Kumar (2015) Ultrasonic quantification of high temperature cyclic damage in an advanced nickel based superalloy. Materials Science and Engineering A, 625 (IF-2.409). pp. 194-204.

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Present paper discusses about a new methodology to quantify cyclic damage through ultrasonic measurement. Based on experimental results, correlations have been made between damage accumulated inside the material due to strain excursions and corresponding ultrasonic parameters. It has been proposed that based on the existing correlation between attenuation coefficient and number of cycles to failure, fatigue failure characteristics can be partitioned into two regimes (a) failures due to early nucleation and rapid propagation of cracks and (b) failures due to delayed propagation and crack coalescence. Plastic strain accumulation and surface crack density have been chosen as two physical parameters directly influencing attenuation coefficient and it has been observed that with increasing plastic strain accumulation, ultrasonic attenuation increases. Between two primary echoes of ultrasonic spectra, some secondary defect echoes have been found. A damage descriptor has been introduced by taking difference between the bandwidth of defect echo and badman echo normalized by overall amplitude frequency distributions of backwall echo. It has been found to bear sensitivity towards surface crack density. This quantitative estimation differentiates between the classical descriptions of damage due to dislocation mediated plasticity, micro crack generation and coalescence. (C) 2014 Elsevier B.V. All rights reserved.

Item Type:Article
Official URL/DOI:http://www.sciencedirect.com/science/article/pii/S...
Uncontrolled Keywords:Nickel based superalloy; High temperature low cycle fatigue; Ultrasonic waves; Fast Fourier transform; Defect echo; Haynes 282
Divisions:Material Science and Technology
ID Code:7179
Deposited By:Sahu A K
Deposited On:18 Mar 2015 10:14
Last Modified:02 Jun 2015 10:08
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