Modelling of interaction between creep and oxditaion behaviour for engineering materials

Abstract

Mechanical test data for design of high temperature components are mainly collected from tests conducted in air even though these are used in different environment. Therefore, in order to predict accurately the performance of a component in actual service it is necessary to develop appropriate constitutive equations taking into consideration the environmental effect. The paper briefly describes how our current knowledge on Continuum Damage Mechanics (CDM) can be utilized to formulate the same. In absence of sufficient experimental data, most of the existing approaches provide only qualitative support for their models. Creep test on specimens having different section sizes, under identical conditions, can provide valuable information on creep/environment interaction. A simple analytical method has been developed to extract the material parameters determining the kinetics of environmental attack from a creep strain-time plot. It has been shown that the material constants thus obtained provide good explanation of the observed section size and geometry effects in steels and nickel base superalloys.