Characterization by acoustic emission of the oxides scales obtained on the steel loaded in bending at high temperature under controlled atmosphere

The objective of this work is to analyze the acoustic signals recorded during the progress of the 4-point bending tests under different atmospheres (air, nitrogen and water vapor) on specimens of steel, at a constant strain rate: 0.11 mm/min and at two different temperatures: 650 degrees C and 900 degrees C. Acoustic analysis will reveal the specificities in terms of acoustic signatures, between different modes of damage that can suffer oxides developed on steel, since the mechanical tests impose constraints that go far beyond the elastic range of these oxides. This corroborates the existence of a correlation between anomalies occurring on different mechanical curves (force-displacement) recorded during four-point bending tests under different atmospheres, the microstructural observations carried out ex situ on the oxides obtained and the presence of lesions at these oxides recorded by acoustic emission in situ conditions.