Abstract
The effect of phosphorus on microstructure and mechanical properties of dephosphorised JIS AC3A alloys was investigated. In 3 ppm phosphorus alloy, eutectic silicon crystallizes in very fine and lamellar structure, and iron base intermetallic compounds crystallizes in very fine one. In case of 12 ppm phosphorus alloy, eutectic silicon takes a coarse acicular shape, and iron base intermetallic compounds are also coarse. Strength of 3 ppm phosphorus alloy is larger than that of 12 ppm phosphorus one. Particularly elongation and absorbed energy of 3 ppm phosphorus alloy are over three times as large as those of 12 ppm phosphorus alloy. By dephosphorising commercial alloys, we removed the deleterious effect of phosphorus on microstructure of eutectic silicon and iron base intermetallic compounds and improved mechanical properties.
