The effect of the twin boundaries on the yield stress of a material

The aim of the study was to analyse theoretically how the twin boundaries formed in a material during recrystallization affect its yield stress. The yield stress (sigma) was considered to be the sum of the two components: the stress (sigma(GB)) due to the effect of grain boundaries upon the propagation of slip and the stress (sigma(TB)) due to the presence of twin boundaries: sigma = sigma(GB) + sigma(TB) Various correlations between the grain size, the frequency of twin boundaries and the yield stress of the material were considered in the analysis. It has been found that the effect of twin boundaries varies depending on whether they present strong or weak obstacles to the dislocation movements during plastic deformation or whether they themselves generate dislocations. Hence, the stress due to twin boundaries (sigma(TB)) can be expended into three components that represent the individual effects of the twin boundaries observed during plastic deformation.