The latest DTI supported programme of research on materials measurement technology aims to go some way towards meeting both of these goals. Residual stresses are those stresses which remain in a component following manufacture, processing, fabrication or assembly. Residual stresses may be classified by the scale over which they are significant, and hence the type of measurement technique used to study them. Macroscopic residual stresses exist over large distances whilst microscopic residual stresses operate over the grain scale or the atomic scale of the material. Residual stresses originate from a variety of sources.
Macroscopic stresses can arise from heat treatment, machining, secondary processing and assembly.
Both types may be present at any one time in a material or component. The importance of residual stresses depends on the particular material, component and application. No single answer can be given. Each case must be examined on it's own merits. It is unlikely that any component will be entirely free from residual stresses induced during manufacturing and processing.