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1. The authors show that for the graphites under investigation the effective stress concentration factor depends on the structural inhomogeneities, and for inhomogeneities of the same type it is practically independent of the limiting strength values. 2. Fine-grain graphites have stress concentration factors about twice those of medium-grain graphites. 3. The values ofaktech calculated from Eq. (1) agree with the experimental results. This equation is suitable for practical applications and for single tests.

1. The deformation and fracture of graphites takes place predominantly as a result of the growth of existing production cracks and pores. 2. The basic relationships for the deformation and fracture of graphites at 20°C are retained (depending on the structural characteristics of the material) up to 1700–2500°C, above which the effect of the macroductility of graphite emerges. 3. A characteristic feature of the high-temperature deformation of graphites is the formation of fibrous structures between the sloping sides of the cracks which act as strengthening ties.

1. Limitations were derived for functions entering into relations obtained earlier to describe the behavior of isotropic graphite materials under load. It was shown that empirical curves conform to these restrictions. 2. The proposed relations were used to determine stress distribution at the tip of a normal-rupture type crack under plane stress conditions. In conclusion, the authors thank Yu. N. Rabotnova for discussing the work with us.