ABSTRACT
A method for characterizing the mechanical response of oxide scales by a depth-sensing submicron indentation technique is described for application to chromia-rich scales grown on a stainless steel. Results on room-temperature micromechanical properties (elastic modulus, hardness, etc.) are presented to provide data for determining scale fracture criteria and to evaluate models in which reactive element additions to alloys modify the mechanical behavior of oxide scales and thereby improve scale adherence. Average values of elastic modulus for thin chromia-rich scales formed on 20-25-Nb steels was in good agreement with that for the bulk chromia. The addition of 0.13% Ce to the steel, which significantly improves scale adherence, did not affect the elastic modulus hardness, strength, or plasticity of the oxide scale. These findings therefore did not support the subject models of scale adherence for cerium. However, the technique of depth-sensing submicron indentation testing appears to offer promise as a method of characterizing oxide scales.
