Characterization of microstructure variations by laser-ultrasound during and after the heat treatment of metals

As sound propagation is related to the mechanical properties of a material, ultrasound have been used to investigate the microstructure of metal for decades. Laser-ultrasonics is particularly well suited for such analysis in metals, as it does not require contact with the metal. This facilitates the observation of changes in microstructure caused by extern parameters such as thermal processing.

In a recent paper, researchers at RECENDT presented two interesting studies of such an application of laser-ultrasonics to the study of steel: direct observation of the hardened zone in crankshafts, and measurement of the effect of temperature on Poisson’s ratio for steel coils. In both cases, the objective is to “see” the impact of heat treatment on the microstructure of the steel.

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Keywords: laser-ultrasonics, ultrasound, metallurgy, hardening, steel