Cored wire injection is a method of alloying addition that uses a metal casing to wrap around the core of material. This prevents reaction between the wire and the ingredients and provides more consistent yield. In addition to this, the process reduces noxious fume emission and the possibility of vaporization of sulphur.
The injection process is used for inclusion modification in secondary steel refining. It is a necessary feature of refining and casting processes. Since it is a cost effective process, the efficiency of injection must be high. However, there are many parameters to be considered in order to achieve the desired results. Therefore, it is important to study the process and its effects on the quality of finished products. Moreover, different operating conditions require various cored wire parameters.
Considering this, a number of mathematical models have been developed to track the melting behavior of cored wires. These models can be used for design and development of new wire types. They can also be used for optimizing the injection process. A 1-D finite volume numerical model has been developed to simulate the thermal phenomena that occur during wire injection in liquid metal baths. Several authors have studied the additive inclusion of bulk alloys in molten baths. But the effect of various operating parameters has not been studied in enough detail.
The first factor to be considered is the diameter of the wire. Ideally, the wire should be at least 13 mm in diameter. Besides, the outer sheath thickness should be at least 0.4 mm. When the diameter of the wire increases, the shell thickness of the sheath will also increase.
Another aspect that can affect the process is the release timing. The release time depends on the size of the wire, the grade of the steel, and the height of the liquid column. At the same time, the travel distance of the wire is dependent on the injection rate. For example, at the optimum injection speed of 120 m / s, the travel distance of the wire would be about 0.8 m. As the injection rate increases, the wire's distance travels until it reaches its maximum.
One mathematical model was developed by Tata Steel for this purpose. Using a novel indirect method, this model was validated against published data. Moreover, this model also takes into account the differences in operating practices in the steel shop.
The model was developed by using a finite difference approach and general purpose mathematical model. The mathematical model predicts the distance traveled by the cored wire before the shell melts completely. Similarly, it is also used to calculate the melting time of the metal casing.
Furthermore, a model has been developed to study the effect of the injection velocity. Interestingly, the distance traveled by the wire does not increase monotonously with the injection speed. Although the travel distance reaches its optimum at the optimum injection rate, it decreases after that. However, the overall decrease in the wire's travel distance is not much.
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