As shown in the table, the impact toughness of the high chromium cast iron samples after modification has been greatly improved compared with that before modification, both as cast and heat treated. When the unmodified high chromium cast iron eutectic solidifies, it grows in a fiber like direction and finally forms a cluster of Daisy like multiphase eutectic.
Sample 1 | Sample 2 | Sample 3 | Sample 4 | Sample 5 | Average value | |
Before modification (as cast) | 3.8 | 3.7 | 3.7 | 3.8 | 3.8 | 3.76 |
After modification (as cast) | 5.3 | 5.32 | 5.35 | 5.25 | 5.28 | 5.3 |
Before modification (heat treated) | 4.1 | 3.9 | 4.1 | 4 | 3.9 | 4 |
After modification (heat treated) | 5.5 | 5.7 | 5.6 | 5.65 | 5.55 | 5.6 |
With the addition of the composite modifier, the rare earth elements in the modifier hinder the space of ferrochromium carbides tending to fiber growth, the volume of eutectic clusters decreases or even disappears, the carbides present isolated and dispersed small blocks, the material structure is obviously refined, and the continuity of high toughness matrix structure is greatly improved. When the sample is impacted, The impact toughness of high chromium cast iron is improved because of the buffer effect on stress concentration; In addition, the rare earth elements in the modifier can purify the grain boundary, improve the grain boundary strength, and improve the impact toughness of high chromium cast iron.