According to the experience of producing aluminum-containing steel, in order to ensure the aluminum content and fluidity of molten steel in LR AH32 Marine steel plate, strict control of terminal carbon content and pre-deoxidation of molten steel during large-bale alloying were adopted to control the oxidization of molten steel, and aluminum addition method of feeding aluminum wire in large-bale was adopted.
High draw - up blowing process is used in converter smelting. The end point carbon content is strictly controlled at 0.07%~0.11%, and the end point temperature is mostly about 1670~1700℃. During the drawing process, 1.0-1.5 kg SiAlBa (silicon barium aluminum) alloy was added into each ton of LR AH32 Marine steel plate for pre-deoxidation. For some furnace with low terminal carbon, the amount of SiAlBa was appropriately increased, so that the Als content in molten steel before argon blowing could be stabilized at about 0.004%~0.005%.
The argon blowing time after alloying should ensure that the inclusions in LR AH32 Marine steel plate are fully floating. Then, according to the temperature of molten steel before argon, the content of carbon at the end point and the amount of slag, 10mm aluminum wire is fed into the steel with the amount of 2.5~4.0m per ton of steel, so as to stabilize the content of Als in the steel above 0.020%.
In order to make the steel pouring smoothly, it is necessary to use the whole process of protective pouring, that is, ladle → tundish → mold protective pouring. The temperature of intermediate LR AH32 Marine steel plate should be ensured at 1540~1555℃, the drawing speed should be stable at 0.70~0.85m/min, and the liquid level of tundish and crystallizer should be stable. In addition, in order to fully float the inclusions produced by aluminum addition, the cooling time of 10~15min should be ensured in the production tissue.
