MICROYIELD STUDY OF DISPERSION STRENGTHENING IN SPHEROIDIZED STEEL AT ROOM TEMPERATURE

Plain carbon steels with 0.48 and 0.95% C were quenched and tempered to 705 C to produce carbide dispersions with spacings on the order of 1 micron. The morphology of the structure consisted of a czrbide-dislocation network. The strengthening due to the dispersion was found to vary linearly with M to the -1/2 power where M is the mean free-ferrite path determined by the entire network. No preyield microstrain preceded the upper yield point. After prestraining the lowest stress at which dislocation movement could be detected was 10 to the 4th power psi; this functional stress was independent of the dispersion and prestrains up to 6.5%. (Author) Studies of the Early Stages of Plastic Deformation.