Influence of structure of grain boundaries and size distribution of grains on the yield strength at quasistatic and dynamical loading

Dependences of the yield strength of metals on the grain size and the dispersion of the grain size are discussed for quasistatic and dynamic conditions of loading. In these two cases, the size distribution of grains influences differently on the slope of the Hall-Petch curve. The presence of wide size distribution of grains shifts the maximal yield strength to smaller grains, which can obstruct an observation of the inverse Hall-Petch effect. According to our analyses, the role of the grain boundary structure is significant both at low strain rate in the coarse-grained materials and at high strain rate in the fine-grained materials.