Seamless steel pipes are widely used because of their high strength and stable mechanical properties. They are often used in industries such as petrochemicals, construction, aerospace, and manufacturing. In order to further improve the performance and quality of seamless carbon steel pipes, annealing is often required. Annealing is a heat treatment process that involves gradually heating the material to a specific temperature and then cooling it to change its crystal structure and improve its mechanical properties.

In the production of seamless carbon steel pipes, annealing conditions are a key issue that directly affects product quality and performance. The key annealing parameters are as follows:

1. Annealing temperature.
Whether the required temperature is reached. Temperature is a key factor. Too high or too low will affect the structure and performance of the steel pipe. Too high temperature may cause coarse grains, and too low temperature will not be fully softened. The heat treatment process of steel generally adopts heat treatment + tempering heat treatment process, which is what we usually call "annealing", with a temperature range of 1040 ~ 1120℃ (Japanese standard).

2. Holding time.
The holding time affects the uniformity of the organization and the grain size. Too long time may cause coarse grains, and too short time may cause insufficient organization transformation.

3. Annealing atmosphere.
The annealing atmosphere generally uses pure hydrogen, and the atmosphere purity is above 99.99%. If the other part of the atmosphere is a rare gas, the purity can be lower, but it cannot contain too much CO2 and water vapor.

4. Furnace wall air tightness.
The seamless steel pipe furnace should be closed and isolated from the outside gas; if radon gas is used as the protective gas, only one exhaust pipe is opened (for igniting the exhausted radon gas). The inspection method can be applied with soap liquid in the gaps of each joint of the annealing furnace to see if there is any gas escaping; 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. Especially the sealing ring in this place is very easy to wear and tear, so it should be checked and replaced frequently.

5. Working pressure of protective gas.
In order to better avoid micro-leakage, the protective gas in the furnace should maintain a certain positive pressure. If it is radon protective gas, it is generally stipulated to be above 20kBar.

6. Water vapor in the furnace.
On the one hand, check whether the raw materials of the furnace wall are dry. When the furnace is loaded for the first time, the raw materials of the furnace wall must be air-dried; on the other hand, whether there are too many water marks on the seamless steel pipe entering the furnace, especially if there are holes on the top of the pipe, do not let water penetrate, otherwise you will destroy the atmosphere in the furnace.

7. Cooling rate
The cooling rate affects the final organization and performance. Too fast may lead to too high hardness, too slow may produce undesirable organization.

8. Steel pipe material
Steel pipes of different materials have different organizational transformation temperatures and speeds during annealing, which affects the formulation of annealing process.

9. Operation process
Operation processes such as furnace loading method and stacking density will also affect the annealing effect.