The multiple strata plasticity model, which was presented in the previous paper by introducing the tensor Q expressing the activating state of slip systems in the polycrystalline metal, has been developed with a new internal state factor B
5. This factor B
5 denotes the ratio of the grains with activating slip systems greater than five to the total grains. The variation features of B
5 and Q can be computationally evaluated with a virtual polycrystalline specimen. The microstructure state, such as dislocation density can be reflected in the internal structure variable A in this model. The relationship between B
5 and A has been examined on the tensile flow curve of pure copper. As a result, a simple formula connecting A with B
5 was determined. Moreover, it has been clarified that this formula is applicable for describing the plastic deformations under other proportional loadings.
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