The grain boundary character distribution effect on the flow stress of polycrystals: The influence of crystal lattice texture

The grain size of a polycrystalline aggregate has an important effect on its properties. Several properties of materials, such as the yield and flow stresses, ductility and hardness have been suggested to show a linear dependence on (average size of grains)−12. A number of models which justify the grain size effect are based on the assumption that the grains in a polycrystal have the same size and the grain boundaries the same properties. Grain boundaries are characterized by differences in their structure and, as a result, in their properties. An experimental study of the grain boundary strengthening effect in a 316L austenitic stainless steel has been carried out on a series of specimens obtained employing a powder-forming process and produced by conventional thermo-mechanical processing. The Brinell hardness was measured and analysed as a function of (grain size)−12. The experimental data, in general, confirm the Hall—Petch relationship. A significant difference is observed in the values of the KH constants. This difference is discussed in terms of the influence of crystal texture on the strengthening effect of the grain boundaries.