How to control the quality of molten iron in melting with induction furnace
Induction electric furnace can make molten iron reach 1500-1550 degrees quickly, which greatly improves production efficiency. But we must pay attention to the control of molten iron parameters. Because the temperature rises quickly, the crystallization core of the molten iron is reduced, the casting is easy to be white, and the processing is difficult. There are many harmful trace elements in pig iron, which affect the performance of castings, etc.
For example, a large amount of supercooled graphite will appear in gray iron castings, and A type graphite is insufficient. Cementite often appears, which seriously affects machining. The hardness test results are relatively low because of the presence of ferrite.
The number of graphite balls in nodular cast iron is reduced, and the ball diameter is larger. Due to the difficulty of eliminating cementite in high temperature smelting, ductile iron elongation is affected. The shrinkage defects of castings increase, even if the pouring riser system is changed many times.
Therefore, in the electric furnace smelting, special attention should be paid to the reduction of graphite crystal core. The foundry should improve the quality of molten iron according to its own situation.
The hot metal smelting temperature should be detected in time, usually controlled at about 1500-1550 degrees.
The time for the molten iron to stay in the furnace is generally 15-30 minutes.
If the molten iron must be hot or left in the furnace for a long time because of the process requirements, then the formula needs to be changed in advance to increase the graphite crystallization core of the molten iron.
The matching power supply of induction electric furnace is best to be appropriately large to meet the needs of producing a furnace of hot metal in 50-60 minutes.
In almost all induction furnace smelting, fewer graphite cores are produced than cupolas, so the pretreatment of molten iron should become a necessary operation for melting.