Manufacturing technology of high alloy roller bottom furnace roller by centrifugal casting

Among all the metal manufacturing processes, the biggest advantage of the casting process is that the chemical composition of the material can be selected independently, so the chemical composition of the alloy can be analyzed and studied to achieve the required material performance. This is more helpful for materials used in extreme environments to obtain the required properties. In the past 20 years, metal centrifugal casting process has been widely used, which is considered by researchers as the final method to remove non-metallic inclusions in steel, which is more effective than static manufacturing process.

There are two ways of centrifugal casting, namely vertical centrifugal casting and horizontal centrifugal casting. Among these two processes, horizontal manufacturing process is the most commonly used, which is also applicable to the processing and manufacturing of furnace roll and horizontal centrifugal casting process schematic diagram. In this process, the molten metal with the required composition is poured into the rotary preheating metal mold from one end. When the mold rotates and the liquid metal solidifies, centrifugal force is generated. The solidification starts from the outer wall of the mold, and has certain directionality, which means that the liquid metal on the inner wall solidifies at the latest, while the defects such as shrinkage caused by solidification only exist in the inner hole, which is usually It can be removed in the subsequent internal processing.

The effective function of centrifugal force is to separate and concentrate the unwanted impurities, such as slag on the inner wall of the hole, so as to produce a cleaner and better performance centrifugal casting part compared with the static casting part.

Generally, the centrifugal casting furnace roll is processed from the outside. According to the requirements of customers, it can also be processed from the inside. The process of processing from the inside can ensure that the casting defects and impurities can be removed during the solidification process. This treatment can prevent the material from producing cracks in the use process. In general, heat-resistant parts in casting state are provided to users without any heat treatment. At the working temperature, the microstructure will change, which is very beneficial to the necessary mechanical properties and the thermal corrosion resistance required for practical application. Centrifugal casting is conducive to the rapid solidification of liquid metal, and leads to the supersaturation of austenite, carbon and other carbides. At the working temperature, carbon elements are precipitated in the form of secondary carbides, which plays a role of creep resistance.

According to the different design structure, the furnace roller is composed of three parts or five parts. In the three part design structure, the centrifugal casting roller is welded to the roller shaft in the manufacturing workshop. The roller shaft is usually made of forged heat-resistant alloy, because the roller shaft is not directly exposed to the high temperature of the heating furnace, and does not need to bear the load of slab, billet and bloom. Compared with cast alloy, the creep resistance of forged alloy is poor because of the defect of its grain size. In the five part design structure, because there is another casting part, the tapered roller neck, through which the centrifugal casting roller and the roller shaft are connected, a complete casting welding structure is formed.