Application of laser ultrasonics to monitor microstructure evolution in Inconel 718 superalloy
1 The Centre for Metallurgical Process Engineering, The University of British Columbia, 309-6350 Stores Rd., Vancouver, BC, Canada V6T 1Z4
2 Ecole Centrale Paris, Laboratoire MSSMat – UMR CNRS 8579, Grande voie des Vignes, 92295 Châtenay Malabry, France
a Corresponding author: firstname.lastname@example.org
Laser ultrasonics for metallurgy is an innovative sensor dedicated to the measurement of microstructure evolution during thermomechanical processing. In this technique, broadband ultrasound pulses are generated and detected with lasers. The properties of the ultrasounds are then related to the characteristics of the microstructure. Ultrasound attenuation is primary originated by the scattering at grain boundaries and its frequency dependence can be related to the grain size. The present work aims to introduce this technology as an exciting tool for metallurgists. As an illustration of its capability, the evolution of the grain size during isothermal annealing from a fine grained structure is in-situ monitored in an Inconel 718 superalloy. Laser ultrasonic measurements are compared with ex-situ metallography observations. Indication of heterogeneous grain growth is observed, correlated to the dissolution of δ-phase particles present in the initial structure. This preliminary study illustrates the potential of this new technique to monitor microstructure evolution in more complex scenarios including recrystallization during simulation of hot forging processes.
© Owned by the authors, published by EDP Sciences, 2014
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