MECHANISM OF THE EFFECT OF PHOSPHOROUS AND MOLYBDENUM IMPURITIES ON TEMPER BRITTLENESS OF STEEL,
ARMY FOREIGN SCIENCE AND TECHNOLOGY CENTER WASHINGTON D C
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Starting with an older hypothesis regarding the possibility of enriching the surface layers of crystals with surface active elements during the heat treatment of polycrystalline materials, the authors investigated the intercrystalline absorption of phosphorous, i.e., diffusion of phosphorous in solid solution, and its effect on temper brittleness. This was done by producing chrome-nickel steel samples having carefully controlled amounts of phosphorous and molybdenum, causing an impact fracture on notched samples, and chemical analysis of the surface of the fractures to determine the percentage of phosphorous and molybdenum present. Sample melts were bored, filled with ferrophosphorous, and studied for evidence of phosphorous diffusion during various heat treatments. With a knowledge of this diffusion, temper brittleness was then simulated in impact samples using this method. The experiments proved that temper brittleness is caused not only by participation of phosphorous, but also by its redistribution diffusion in the solid solution during heat treatment.
- Metallurgy and Metallography