What are the key elements that affect the annealing of seamless steel pipes?

The gloss of the annealed seamless steel pipe determines the quality of the product. There are also many influencing factors. Here are five key factors:

1. Annealing temperature.
Is the annealing temperature the required temperature? The steel heat treatment process generally adopts the heat treatment and tempering heat treatment process, that is, "annealing" as we usually say, and the temperature range is 1040~1120 °C (Japanese standard). According to the observation hole of the annealing furnace, the stainless steel pipe in the annealing area should be in the condition of incandescent lamp, but there is no softening and relaxation.

2. Annealing atmosphere.

Generally, pure hydrogen is used as the annealing atmosphere. The purity of the atmosphere is above 99.99%. If the other part of the atmosphere is a rare gas, the purity can be lower, but it must not contain too much CO2 and water vapor. 

3. Furnace wall airtightness.
The thick-walled seamless steel tube furnace should be closed and isolated from the external gas; if radon gas is used as the protective gas, only one exhaust pipe is open (for igniting the radon gas discharged). The inspection method can be smeared in the gap of each connection head of the annealing furnace with soap solution to see if gas escapes; the area where the gas is very easy to escape is the area where the annealing furnace enters the pipeline and the area where the pipeline exits. The sealing ring in this place In particular, it is very easy to wear and tear, and it should be checked and replaced frequently.

4. Protective gas working pressure.
In order to better avoid micro leakage, the protective gas in the furnace should maintain a certain positive pressure. If it is a radon gas protective gas, it is generally specified above 20kBar.

5. Water vapor in the furnace.
On the one hand, check whether the raw materials of the furnace wall are dry. When the furnace is installed for the first time, the raw materials of the furnace wall must be air-dried; on the other hand, whether the seamless steel pipe entering the furnace has too much water traces, especially if there are holes on the top of the pipeline, it will Don't let water seep in, otherwise it will destroy the atmosphere of the stove.