ABSTRACT
This chapter describes the results of investigation by transmission electron microscopy of the evolution of the dislocation substructute with the measurement of the scalar density of dislocations in a martensitic steel. It also determines the relationship of the scalar density of dislocations with the grain sizes, the size of the dislocation fragments and the cells. The chapter focuses on the critical grain sizes determined in experiments on pure metals and alloys. It also focuses on the problem of internal stresses which are formed by the geometrically necessary dislocations. The chapter presents the typical size distribution functions of the grains for the sub- micropolycrystalline copper and nickel. Intragranular deformation leads to the formation in them of initially a chaotic dislocation structure and then a cellular dislocation structure. The chapter presents the analytical dependence of the scalar density of the dislocation on the size of the fragments and cells in the deformed martensitic steel.
