Water-cooling die casting production process of plate blank used for medium plate

[0017] The present invention will be further described below in conjunction with the examples.

[0018] A water-cooled die-casting production process for high-demand die steel P80 medium-thick plate slabs, the production process adopts argon protection pouring in the whole pouring process to isolate the contact with the air after the molten steel flows out from the nozzle during the pouring process; The solid mold slag is used to protect the casting to ensure the surface quality of the slab; the rising hole of the convection steel is adjusted to make the molten steel rise smoothly in the water-cooled die casting to ensure the surface quality of the slab; the details are as follows:

[0019] In the whole pouring process, argon gas protection is used for pouring, figure 1 It is a schematic diagram of the argon protection casting adopted in the present invention. The pouring device consists of an argon gas group 1, an argon gas pipeline 2, a double argon blowing ring 3 and a sealing cover 4. The sealing cover 4 is arranged between the ladle water outlet 5 and the middle casting pipe 6 , the argon blowing double ring 3 is arranged between the sealing cover 4 and the ladle water outlet 5 ; the argon gas group 1 is connected with the argon gas pipeline 2 . Blow argon to the whole pouring system before pouring. The air in the pouring system can be eliminated by using the characteristic that the specific gravity of argon is greater than that of air, so as to reduce or even isolate the contact with the air after the molten steel flows out of the nozzle during the pouring process.

[0020] The use of solid mold slag to protect the pouring can avoid surface defects such as turning skin and pits, and at the same time, it has a certain adsorption effect on the inclusions in the molten steel during the pouring process. Surface slag scarring and near-surface slag inclusion defects are formed in steel. Part of the mold slag is added just after the injection flow is flattened to the bottom of the mold, and it is gradually added in the later stage, which can ensure the surface quality and reduce the occurrence of slag defects.

[0021] Adjust the rising hole of convection steel. In fact, the rise of water-cooled die casting is inconsistent in the early stage of pouring. The side close to the middle casting pipe rises faster and turns more violently, and it is easier to produce slag defects on the side near the middle casting pipe. Therefore, the rising hole of convection steel is The diameter of the rising hole on the side close to the middle casting pipe is adjusted to be smaller, and the diameter of the rising hole on the side far from the middle casting pipe is relatively larger, so that the rise of the molten steel in the water-cooled die casting will be stable and further reduce the volume Possibility of slag defects. The originally used water-cooled die casting ascending holes had 7 holes evenly distributed with a diameter of φ40mm. In the present invention, the diameters of the two ascending holes on the near-middle casting pipe side were changed to φ20mm, and the diameters of the remaining ascending holes on the far-center casting pipe side were changed to 30mm, a total of 10. It is found that the molten steel rises smoothly during the pouring process. Double-circle double argon protection is used for pouring, and argon is blown to the entire pouring system before pouring, and argon protection is also used throughout the pouring process. After pouring, the molten steel just fills the bottom of the solid mold, and the mold slag is sprinkled into the part. During the pouring process, the mold slag is added according to the consumption of the mold slag until the pouring process ends.

[0022] The produced billet is ultrasonically tested to JB/T4730.3-2005 standard grade I after rolling the medium plate, the inclusion grade is low, the grain size reaches grade 11, and the comprehensive performance is good.

[0023]