The possible defects of the casting slab In the continuous casting processIn the whole operation of the continuous casting machine, some defects will appear in
The possible defects of the casting slab In the continuous casting process
In the whole operation of the continuous casting machine, some defects will appear in the casting billet, which affects the normal production. This is where we need to pay attention. Only by understanding the specific type can we better operate it.
Slab defects:
1.Corner cracks. After the lower mouth of the crystallizer parts is severely worn, a larger air gap is formed between the copper mould tube and the casting billet, and a larger thermal resistance is formed. As a result, the cooling of the lower mouth is too weak, and the blank shell becomes thinner. At the same time, due to the severe wear of the lower mouth, the corners of the zero section have too strong cooling, which causes the cooling gradient from weak to strong to be too large, resulting in stress concentration. In addition, due to the uneven thickness of the blank shell, the cast slab becomes rhombohedral, and corner cracks are easily generated.
2.Billet defects: middle cracks. When the cast slab passes through the secondary cooling zone, the cooling is uneven, and the thermal stress generated by the excessive temperature rise exceeds the maximum stress borne by the columnar crystals. In addition, the development of columnar crystals increases the probability of the formation of intermediate cracks.
3. Depress cracks. Excessive pressure of pulling and correcting rolls causes depression cracks in the solid-liquid two-phase zone of the casting slab that is solidifying. For cast billets with developed columnar crystals and intermediate cracks, larger reduction cracks are often formed along the direction of the green billet.
4. Loose center. The columnar crystals on both sides of the slab grow toward the center, and when they meet together, they create a "bridge". It prevents the molten steel above the bridge from supplementing the solidification and shrinkage of the molten steel below the bridge. When the molten steel below the bridge is completely solidified, many small pores are left.
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Harm of too high temperature: when molten steel out of cooper mold, the billet shell is thin and easy to break out; The accelerated erosion of refractory can ea
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In continuous casting, low corrosion resistance often occurs, which directly leads to uneven composition and will eventually affect the smelting quality. In or