EFFECTS OF THERMAL AGEING ON THE LATTICE STRAINS IN A SINGLE PHASE POLYCRYSTALLINE MATERIAL MEASURED BY NEUTRON DIFFRACTION

摘要

In-situ neutron diffraction combined with the incremental deformation was used to investigate the lattice strain response in an ex-service Type 316H austenitic stainless steel. The material was subjected to either a short term or a long term high temperature prior deformation. Both a solution heat treated and an ex-service plus laboratory aged microstructural condition was considered. The results demonstrate that there is a difference between these two microstructural conditions in terms of the lattice strain response to the applied stress. In addition, after the prior deformation at high temperature was applied to the specimens for both microstructural conditions, the lattice strain response to the applied stress showed a strong dependence upon the initial microstructure, especially for {200} and {220} grain families. The influence of thermal ageing and prior high temperature deformation on the meso-scale polycrystalline material deformation mechanism is discussed.