How to prevent the continuous casting billet longitudinal crackThe key to prevent the longitudinal crack of continuous casting billet is the uniformity of the g
How to prevent the continuous casting billet longitudinal crack
The key to prevent the longitudinal crack of continuous casting billet is the uniformity of the green shell on the meniscus surface, so the following measures should be taken:
(1) The mold adopts reasonable taper, and the best shape of the inner cavity of the copper tube or copper plate, as far as possible to make the heat flux in the mold tends to be uniform.
(2) Use good performance of the protection slag.
(3) The outlet Angle and insertion depth of the immersed nozzle should be appropriate, and the installation should be centered to reduce the scour of the casting billet shell by the injection flow and make its growth uniform.
(4) Determine the reasonable pouring temperature and casting speed according to the steel type.
(5) Keep the liquid level of the mold stable. If the fluctuation interval of liquid level increases from ±5mm to ±20mm, the longitudinal crack index increases from 0 to 2.0. Thus it can be seen that the fluctuation interval of the liquid level of the mold should be controlled within ±5mm.
(6) The chemical composition of steel is controlled in an appropriate range.
(7) Hot-top crystallizer is used. In other words, materials with poor thermal conductivity are inserted into the 75mm copper plate area in the meniscus area to reduce the heat flux of the mold by 50%-70%, delay the contraction of the billet shell, reduce the sag on the billet surface, and thus reduce the probability of crack occurrence.
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