抄録
This paper proposes a theoretical model of the ductile-brittle transition in machining of hard-brittle materials based on.the fracture mechanics, and discusses the enhancement of the critical area by the externally applied hydrostatic pressure. The theory suggests that the critical area is proportional to K_<IC>^2/σ_O^2 , and that variation of the critical area by externalhydrostatic pressure depends on K_<IC>^2/σ_O^3. Machining test under external hydrostatic pressure was conducted on four kinds of hard-brittle materials. Results are compared with the theory, and effects of material properties on the critical area is discussed.
