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What are the three major smelting methods and ingot casting technology of precision alloy?

2024-07-06

Precision alloys are metal materials with special physical properties (such as magnetism, electricity, heat, etc.). Most precision alloys are based on ferrous metals, while a few are based on non-ferrous metals.

 

Smelting process

The characteristic of vacuum induction melting is that in the case of high quality raw materials, the content of high purity gas is less, and the chemical composition is controlled correctly. This is because the molten steel in the vacuum induction furnace has been refined in high vacuum for a long time. Due to the use of strong induction stirring and intermediate sampling methods, the capacity of the furnace has a tendency to expand. For example, the United States has a large vacuum induction furnace with a capacity of 15 tons. For the production of superalloys and precision alloys, West Germany has the world's 30 ton vacuum induction furnace.

 

The use of electric arc furnace to smelt precision alloys is a breakthrough in ancient tradition. As mentioned above, precision alloys as a whole have different requirements. The specific requirements of smelting in an economic way are more scientific and reasonable. In 1974, Shanghai Iron and Steel Research Institute began to use electric arc furnace smelting 4J29 and other 30 kinds of precision alloys, and achieved good results. At the same time, learning from the rapid development and technical transformation of foreign electric arc furnace equipment in recent years, we can better develop precision alloys in electric arc furnace smelting.

 

Ingot casting technology is an indispensable part of the smelting process, especially for high alloy steel and high strength steel. Because in most cases, the carelessness of the spindle will give up the previous work. In order to solve the quality problem of the ingot, the ball core is to prevent secondary oxidation during the casting process.

1. Vacuum casting is to complete the pouring operation under vacuum conditions such as vacuum induction furnace, but its disadvantage is large investment and high operating cost.

2. Protective casting is to press the inert gas protection device around the nozzle at the bottom of the ladle to prevent the molten steel from polluting the air. At the same time, the protective slag is isolated from the air on the surface of the ingot mold.

3. Horizontal continuous injection. For a small amount of high alloy steel, horizontal continuous injection is a very effective method. This is because horizontal continuous injection not only improves the material conversion rate, but also has a unique advantage in preventing secondary oxidation during the pouring process. This is because the tundish of the horizontal continuous casting machine is directly connected to the mould, presenting a completely closed system. At the same time, the molten steel is quickly cooled by the water-cooled copper mold, and the unique crystal structure significantly improves the alloy with poor thermal workability.