Effect or Inoculation on Microstructure and Properties of Low C-Mn and Low Alloy Steels

Effect of the addition of various inoculants on the morphology and mechanical properties of low C-Mn and low alloy steel samples is studied by thermal and mechanical processing of the samples after solidification. According to the results obtained from metallographic studies with the electron microscope and microanalysis with x-rays, the distribution of inoculating agents in the steel matrix is seen in the form of very fine precipitates dispersed in the austenite-ferrite microstructure. These precipitates retard low-temperature recrystallization of austenite, increase the specific boundary area of retained grains and enhance concentration of more favored nucleation sites when austenite to ferrite transformation occurs at the final cooling stage from normalization temperature and thus cause a recognizable refinement in the steel microstructure. Both the strength and hardness of the samples are considerably enhanced by increasing the content of the inoculating agents, while the decrease in the elongation of the samples is limited to an acceptable range.