Vacuum refining furnace---the basic knowledge

Vacuum Degassing crafting process

First, the molten steel is sucked into the vacuum chamber, and then argon is blown into the molten steel on the side walls of the two risers. The argon gas rapidly expands under the action of the high temperature of molten steel and the low pressure of the upper part of the vacuum chamber, causing the density of the mixture of molten steel and gas to continuously decrease along the height of the immersion tube. Under the action of the pressure difference caused by the density difference, The molten steel enters the vacuum chamber. The mixture of molten steel and gas entering the vacuum chamber releases gas under the action of high vacuum. At the same time, the molten steel becomes molten steel beads, and the gas to be removed from the molten steel beads is released into the vacuum under the action of high vacuum. In the process, the molten steel beads are turned into smaller molten steel beads, thereby achieving a very good degassing effect. The molten steel that has released the gas returns to the ladle along the downcomer. After several cycles in this way, the gas in the molten steel can be reduced to a relatively low level.

At the beginning of the cycle treatment, sampling and temperature measurement are required every 10 minutes; when the treatment is about to end, sampling and temperature measurement are performed every 5 minutes. According to the results of sampling and analysis, if it is necessary to add alloy materials (including deoxidizers or other additives), an automatically controlled feeding hopper can be operated, and the alloy materials can be fed into the vacuum chamber at a constant feeding rate without breaking the vacuum. .

 Vacuum Degassing advantage

(1) Better degassing effect. Due to the input of driving gas, a large number of bubble nuclei are generated in the riser, and the molten steel entering the vacuum chamber is sprayed into fine droplets, which greatly increases the degassing surface area of the molten steel, which is beneficial to the degassing.

(2) The temperature drop is small. Generally, the temperature drop in the treatment is only 30-50℃, and electric heating can be carried out during the degassing process, so the molten steel only needs a little overheating in the furnace.

(3) Large processing range. The same equipment can process molten steel of different capacities, and it can also be processed in electric arc furnaces and induction furnaces.

Because the vacuum cycle degassing method has the above advantages, it develops rapidly and has a wide range of applications. According to statistics, more than 100 RH devices have been put into production, and the processing capacity of the largest equipment is 350t. Some factories in my country have also selected RH devices. For example, after Daye Steel Plant first installed a 60-100tRH device (commissioned in 1967), then Shanghai Heavy Machinery Plant (commissioned in 1972), Wuhan Iron and Steel Company's second steelmaking plant (1#RH1979, 2#RH1990 put into production), and Baoshan Iron and Steel General Plant's steelmaking plant (put into operation in December 1985) also installed this equipment. Practice has proved that this equipment is flexible in operation,

The induction melting vacuum degassing furnace can realize the following conventional processes:

Melting solid materials in the atmosphere (vacuum melting can be an option)

Melting solid materials in a controlled atmosphere

Make the alloy distribution uniform and adjust the chemical composition

Vacuum degassing (removal of hydrogen and nitrogen)

Reduce residual elements under low pressure, such as lead, zinc, bismuth, etc.

Deoxygenation using a combination of vacuum and carbon-oxygen reaction

Decarburization-enhanced carbon-oxygen reaction at low pressure ensures that low-content carbon steel has a good decarburization effect

Can be bottom blown with argon through the vent plug

Compared with the intermediate frequency furnace, the quality of the products produced by the induction melting vacuum degassing furnace has been greatly improved:

Greatly improve the mechanical properties of the product, such as the degree of metal yield resistance, high ductility and good impact strength, fatigue strength, stress rupture strength and high temperature characteristics.

Improve process characteristics, such as hot workability, weldability and machinability

Due to the strong deoxidation effect of carbon, the residual magazine in the metal is more refined, and the microstructure cleanliness is better

Significantly reduce