In situ laser-ultrasonic monitoring of Poisson?s ratio and bulk sound velocities of steel plates during thermal processes
Sprache des Titels:
We demonstrate the in situ measurement of zero-group-velocity Lamb waves and thickness-resonances in steel sheet samples using laser-based ultrasound, while changing the sample temperature from ambient to 1000? C. The ratio of resonance frequencies yields the temperature dependent Poisson?s ratio of its material without requiring knowledge on the sheets? thickness. Changes in the temperature derivative of the determined Poisson?s ratio reflect changes in the microstructural constituents. We show that additional resonances present in the response spectrum can be used to cross-check the evaluation. With additional knowledge on the thickness, longitudinal and transverse sound velocities are determined as well. We find good qualitative agreement between the temperature dependence of the measured quantities and reference data obtained from dilatometry and thermodynamic material simulations ?