Volume 1, Issue 4 (July 1973)
The Influence of a Dispersion on the Ductility and Fracture Behavior of Iron
Iron and iron-thoria strips were produced by a technique involving coprecipitation, hydrogen reduction, compaction, and hot rolling. Flat specimens of iron and two thoria dispersion strengthened alloys were pulled in tension at temperatures in the range 77 to 373 K. The low temperature ductility of the hot-rolled powder compacts was improved by the dispersion, and the ductile brittle transition temperature was reduced. The onset of mechanical twinning, discontinuous yielding, and Luders band failures was suppressed to lower temperatures in the dispersion hardened material. The necking and fracture behavior was strongly influenced by the dispersion. Stringers of thoria particles acted as crack initiation sites, particularly if they lay transverse to the loading direction.