IAEA CRP 1314 (2006-2009)Background
Developement and Application of the Techniques of Residual Stress Measurements in Materials
The large penetration depth and selective absorption of neutrons make them a powerful tool in non-destructive testing of materials with large samples. Residual stress formed in a material during manufacturing, welding, utilization or repairs can be measured by means of neutron diffraction. In fact neutron diffraction is the only non-destructive testing method, which can facilitate 3-D mapping of residual stress in a bulk component. Such studies are importance to improve the quality of engineering components in production and to optimise design criteria in applications. Anisotropies in macroscopic properties like thermal and electrical conductivities, for instance of fuel elements, and mechanical properties of materials depend on the textures developed during their preparation or thermal treatment. Such textures can be studied using neutron diffraction techniques.
Neutron diffraction (ND) and X-Ray diffraction (XRD) are based on the same principle and are complementary. XRD is suitable for surface measurements while ND can probe thick specimens in bulk. Although XRD is easily available, it is not practically useful for probing real industrial components, as it yields only localized information at the specimen surface, which usually is not representative of the bulk sample. In its simple form the instrument for residual stress measurement is a two axes powder diffractometer with some specific requirements and / or attributes and can be installed on a medium flux research reactor to improve the effective utilization.
There are some facilities having well designed, optimised and characterised instrument. The expertise and infrastructure exists to develop and maintain the facility. For convenience sake such facilities are defined as type A facilities. On the other hand there are many research reactors where either the instrument is not available or is not optimised, basic infrastructure is not available or trained manpower is missing. Such facilities remain under utilised. For convenience such facilities are defined as type B facilities.Objectives
The main objective of this CRP is to develop the technique including the design of instruments, the process of data acquisition and analysis and expertise in residual stress measurement - an application as a nondestructive probe in material technology and industry. Other aims are: