Small Punch and Indentation Tests for Structural Health Monitoring

Abstract

The microstructural and metallurgical changes due to high temperature and high pressure applications, irradiations etc. cause a significant degradation of the mechanical properties of materials in refinery industries, nuclear industries, power plants, oil and gas pipe lines, aging aircrafts etc. That's why materials of in-service components in these industries need periodic health assessment to evaluate the degradation of mechanical properties. In the present work Finite Element simulation of indentation technique has been done for refinery materials by using ABAQUS FEM Code and different mechanical properties has been obtained. For properties evaluation by indentation test technique, some material constants is to be required. After carefully studying it has been found that in case of service exposed components there is a large difference between actual value of these material constants and assumed approximate values, this may be due to the fact that material constants change due to change in microstructure with the exposure to high temperature for a long time. This incorporates inaccuracy in property evaluation by indentation technique. The present work shows that properties obtained by using small punch test are quite accurate and that's why these properties can be used to find out Indentation Technique constants. This methodology is also developed here for finding out Indentation technique constants by using the value of yield strength & equation of true stress-true plastic strain curve obtained by using small punch test. In this way accuracy of Indentation technique can be increased. Thus a new methodology has been developed to find out the mechanical properties of service exposed components by clubbing the two techniques i.e. indentation technique, small punch technique.