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Common sense problems that steelmaking must understand (3)

1. Combine the situation before, during and after the blowing, and briefly describe the operation of the constant pressure gun.

Answer: The constant flow variable gun position operation is in the process of blowing in a furnace steel, the oxygen supply flow rate remains unchanged, and the blowing position is controlled to change the interaction between the oxygen flow and the molten pool to control the blowing. Most manufacturers in China use a staged constant flow variable gun position operation. Oxygen lance operation is not exactly the same due to different tonnages of the converter, nozzle structure, raw material conditions and steel grades. There are currently two lance operation modes. 1 high-low-high-low gun position mode. The open blow gun position is higher, and the initial slag is formed early. When the second batch of rice is added, the gun is lowered at the appropriate time. When the middle slag is blown back, the gun can be added or an appropriate amount of flux can be added to adjust the slag fluidity to shorten the blowing time and the end point. Pull carbon out of steel. (2) High-low-low gun position mode. The open blow gun position is higher, and the initial slag is formed as soon as possible; the gun position is gradually reduced during the blowing process, and an appropriate amount of flux is added in the middle of the blowing to adjust the slag fluidity, and the carbon steel is extracted at the end point.

2. Write the carbon oxidation reaction formula of converter steelmaking and indicate the carbon-oxygen reaction generated by the spray.

Answer: [C]+1⁄2{O2}={CO} [C]+(FeO)={CO}+[Fe] (carbon-oxygen reaction caused by splash)[C]+[O]={CO}

3. What is a non-metallic inclusion? Where is the main source?

Answer: Non-metallic phases that are produced or mixed during smelting, casting, and solidification of molten steel are called non-metallic inclusions. Non-metal phases are compounds in which some metal elements and Si are combined with non-metal elements, such as oxides, nitrides, sulfides, and the like. Due to the presence of inclusions, the continuity of the steel matrix is ​​destroyed, resulting in unevenness of the steel structure, affecting the mechanical properties and processing properties of the steel. However, non-metallic inclusions also have a favorable effect on steel, such as controlling the fine grain size, precipitation hardening, promoting grain orientation, and improving the cutting performance of steel.

4. How to classify according to room temperature and carbon content steel?

Answer: (1) Eutectic steel: 0.0218 < C < 0.77%; (2) Eutectoid steel: C = 0.77%; 3) Hypereutectoid steel: 0.77% < C < 2.11%.

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