Critical shapes and arrangements of carbides in high-speed tool steel

High-speed tool steel can be regarded as a particle reinforced composite consisting of carbides embedded in a martensitic matrix. The internal stress distribution in such a material shows a significant dependency on various parameters such as geometry, material and arrangement of the inclusions as well as external loading conditions. Recent theoretical results confirm the experimental observations that matcrial failure is initiated by cleavage fracture of the carbides rather than matrix rupture. Given a constant volume-fraction of particles in the composite material a Weibull approach is employed to estimate the fracture probability of the carbides. Various inclusion shapes are examined for uniaxial loading conditions. The correlations between the probability of fracture of the inclusion and the parameters defining the geometry of the model will be demonstrated. Particular emphasis is put on the significance of the Weibull modulus m.