New type of breathable brick helps induction furnace to remove impurities

The existence of gas inclusions and oxide inclusions in castings is the main reason for poor mechanical properties and corrosion resistance of castings, and the content of various inclusions in castings is closely related to the purity of molten steel in the induction furnace. Although AOD (Argon Oxygen Decarburization Refining Furnace), VOD (Vacuum Oxygen Blown Decarburization Refining Furnace) and other refining equipment have good results, the investment and operating costs are high, and they are not suitable for a large number of small and medium-sized foundries. At present, most of the process for producing castings in induction furnaces adopts the remelting method, which has no refining function and cannot remove various inclusions brought in during the remelting process. The quality of molten steel cannot be guaranteed, resulting in low casting yield and low grade. How to reduce the content of various inclusions produced in the remelting process of stainless steel castings with high efficiency and low cost has become an urgent issue for enterprises that use induction furnaces to produce castings.

Installation of ventilation bricks. The installation of the breathable brick in the induction furnace is very simple. There is no need to carry out large-scale transformation of the structure of the induction furnace. Only a circular hole with a diameter of 40 mm to 60 mm is drilled on the asbestos board or prefabricated block at the bottom of the furnace to guide the breathable brick. The argon blowing pipeline can be equipped with bottled industrial argon as the argon source. The furnace building process of the induction furnace with air-permeable bricks is the same as that of the ordinary induction furnace.

The test report of molten steel shows that the content of [O], [N] and [H] in molten steel is significantly reduced when the argon blowing process is used compared with that without argon blowing. At the same time, the test report also pointed out that the content of non-spherical inclusions in molten steel was lower than the forging standard, and the content of spherical oxide inclusions reached the 0.5A standard. This result shows that the application of the argon blowing process with breathable bricks in the intermediate frequency induction furnace can effectively improve the quality of molten steel and ultimately improve the grade of castings.