Induction Furnace Lining Failure

Induction furnace lining failure is common, and lining cracking is one of them. The induction furnace lining is an important component of an intermediate frequency furnace, and it is also a vulnerable component within the furnace. Cracking and peeling often occur, requiring timely repair or replacement. So what is the reason for the cracking of the induction furnace lining, and what are the causes and solutions for this situation?

1. Random Crack

Reasons:

As a kind of induction furnace lining failure, the causes of random cracks are mostly due to the impact of large lumps of material on the cold lining during charging in the intermediate frequency furnace, while the steel structure of the furnace is not very firm, resulting in the displacement of the coil during tilting, causing damage to the lining and causing cracks. During the production of a 20-ton medium-frequency furnace, only half of the molten iron is melted at one time, resulting in a low liquid level in the furnace lining. At the same time, the residence time of the molten iron is too long, and the temperature difference between the upper and lower parts of the furnace lining is too large, leading to the occurrence of random cracks when cooling the furnace body.

Terms of Settlement:

During the use of the induction furnace, attention should be paid to maintaining a high level of the metal to be used, so that the furnace wall can uniformly withstand erosion and erosion. Before pouring, sufficient power should be turned on to shorten the mixing time. Generally, the furnace temperature can be maintained at 1300 degrees Celsius, and as low as possible below 1400 degrees Celsius, to maintain a stable melting rate of cold materials; During melting, frequent removal of slag can rapidly flow metal into the molten stream, thereby reducing the erosion of slag on the furnace lining. The crucible mold and the induction coil should be placed concentrically to ensure uniform thickness and a deviation of less than 3mm.

2. Transverse Crack

Causes: 

There are three reasons for the occurrence of transverse cracks. More commonly, during tying, the front and rear materials are not cut loose with a degassing fork, resulting in delamination between materials. Secondly, the cooling speed of the lining at the top of the furnace is too fast during cooling. When the temperature difference between the lining and the lower lining is large, the uneven shrinkage of the lining during the quenching process can easily cause strain and lateral cracking of the lining. In addition, due to physical reasons, the structure of the furnace body is loosened, making the mica backing lose, and causing faults in the furnace lining.

Solution: 

For this type of induction furnace lining failure, the treatment method mainly starts with the furnace construction process, and each furnace construction should use the same weight of furnace material to maintain a uniform density of the furnace lining and tamp it firmly; After each layer is tied and before adding another layer of material, a flat shovel can be used to loosen the compacted surface of the furnace lining by about 20mm, so that the layers can be tightly occluded. Before building the furnace, the furnace charge should be fully mixed to avoid any debris falling during the process of building the furnace.

3. Longitudinal Crack

Cause: 

The causes of induction furnace lining failure such as a longitudinal crack mostly due to unreasonable rapid cold and thermal cycling impacts caused by non-standard cold start melting operations, resulting in multiple longitudinal cracks in the furnace lining.

Solution: 

The knotted furnace lining should be dried immediately. The furnace cannot be shut down for the previous week or half a month. It should be continuously melted and insulated to form a thicker sintered layer to resist the tensile stress caused by cooling shrinkage.

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