EFFECT OF DISPERSIONS ON MECHANICAL PROPERTIES

Abstract : A brief summary is presented of existing knowledge on the dependence of properties on the microstructure of polyphase alloys. No satisfactory method was formulated for predicting the plastic properties of alloys containing one or more ductile phases. The problems considered of major importance center about grain size effects, orientation effects, simultaneous satisfaction of stress equilibrium and continuity over the gain boundary regions, and heterogenous deformation and stressing over a single grain. The plastic behavior of alloys containing hard intermetallic phases dispersed in a soft ductile matrix was shown to be dependent primarily on the mean distance between the hard particles. Data are reviewed on the effects of dispersions on the deformation strengths of a series of steels. These data reveal that, within a rather broad scatter band, the flow strength dispersions of carbides in ferretic steels decreases linearly with the logarithm of the mean ferrite path independent of carbon content or type of dispersion, be it entirely lamellar, lamellar islands in ferrite, or spheroidal.