INFLUENCE OF INOCULATION ON THE MASS EFFECT IN HEAVY SECTION FERRITIC SPHEROIDAL GRAPHITE CAST IRON

The effect of inoculants was confirmed to improve the mass effect of ferritic spheroidal graphite iron castings with heavy sections. In the first series of tests, primary inoculation was performed simultaneously with the spheroidizing treatment, followed by the addition of post-inoculant, and the effectiveness of this method was evaluated in the terms of nodule count and mechanical properties. Post-inoculation is the common term for inoculation after initial treatment. In the first series of tests, six inoculants were evaluated in separately cast test samples, for the second part of the evaluation, Fe-Si-Ca-Zr and Fe-Si-Ca-Ba-(1) were selected. In the second series of tests, these inoculants were used and evaluated by cast on test samples with the wall thickness of 40 and 70 mm. The results showed that possibly the change to Fe-Si-Ca-Zr provided the greatest increase in the nodule count. Tensile properties of samples post-inoculated Fe-Si-Ca-Zr showed almost the same values for tensile strength, proof stress, and elongation at 40 mm and 70 mm wall thickness. In impact tests, differences in absorbed energy were observed in samples with a wall thickness of 70 mm, with Fe-Si-Ca-Zr having the highest absorbed energy. Therefore, the Fe-Si-Ca-Zr inoculant is effective post-inoculation for reducing mass effect. Also, the factors were discussed through electron probe micro analyzer (EPMA) analysis of inoculant.