Continuous Casting Technology of Q355GNH

The continuous casting process is fully protected, and steel plate mold slag for container steel is added to the crystallizer.

Q355GNH steel is prone to breakout accidents during the casting process. The reason is that Q355GNH steel contains Cu, and the billet shell is easy to stick to the copper plate, resulting in bonded breakout. Moreover, Cu in Q355GNH steel will cause cracks on the surface of the slab, which will cause crack breakouts in the case of high casting speed. The content of alloy elements in Q355GNH steel is high, the shrinkage rate of the billet is large during the solidification process, and a large air gap is easily formed between the billet shell and the inner wall of the crystallizer, which hinders the heat transfer of the billet shell, and the billet shell becomes thinner, and it will also cause breakout.

Therefore, it must be strictly centered when starting to pour or replace the nozzle to avoid bias flow. The casting speed is strictly limited to no more than 1.1m/min during the casting process of Q355GNH steel. When the mold slag is denatured, the slag should be replaced in time, and the water temperature of the crystallizer for Q355GNH steel should be increased to reduce the amount of secondary cooling water, slow cooling of the slab.