Comments on the Quantification of Mechanical Adhesion Energy of Thermal Oxide Scale on Metallic Substrate Using Tensile Test
The tensile test, accompanied by the corresponding theoretical model, has been developed to quantify the mechanical adhesion energy of the oxide scale on metallic substrate in our previous works. The method to quantify the adhesion energy took into account the effect of residual stress. The effect of the variation of the measured residual stress on the quantified adhesion energy is assessed in this paper. For the scales failed at strains initiating the spallation of 0.018 and 0.011 followed by the transverse crack, it was found that the quantified adhesion energy of the oxide is not sensitive to the variation of the residual stress measured in the range from 0.5 to 2.0 GPa. This is due to the compensation of the decrease in stored energy due to the stress applied in the loading direction (x direction) and the increase in stored energy due to the stress applied in the direction perpendicular to the loading direction (y direction) when the residual stress increases. For the scale failed by the transverse crack followed by the spallation, the quantified adhesion energy tends to be sensitive to the variation of the measured residual stress. The assumption of energy relaxation during the tensile test is alternatively proposed. It is assumed that the energy stored due to the stress in x and y directions is totally released at the first crack. The energy stored due to the stress in y direction from strain initiating the crack to strain initiating the spallation is used in the quantification of the adhesion energy. The scatter of the adhesion energy values quantified by this method and those measured by the inverted-blister test is reduced comparing to the results reported in the previous work.
Pierre Steinmetz, Ian G. Wright, Alain Galerie, Daniel Monceau and Stéphane Mathieu
S. Chandra-ambhorn et al., "Comments on the Quantification of Mechanical Adhesion Energy of Thermal Oxide Scale on Metallic Substrate Using Tensile Test", Materials Science Forum, Vols. 595-598, pp. 907-914, 2008