Key elements of smls pipe annealing

Key elements of smls pipe annealing

The glossiness of annealed carbon smls pipe determines the quality of the product. There are many influencing factors. Here are five key factors:

1. Annealing temperature.

Whether the required temperature is reached. The heat treatment process of steel generally adopts the quenching and tempering heat treatment process, which is what we usually call "annealing". The temperature range is 1040~1120℃ (Japanese standard).

2. Annealing atmosphere.

Pure hydrogen is generally used as the annealing atmosphere, and the purity of the atmosphere is above 99.99%. If the other part of the atmosphere is a noble gas, the purity can be lower, but it cannot contain too much CO2 and water vapor.

3. Furnace wall air tightness.

The seamless steel tube furnace should be sealed and isolated from outside gas; if radon gas is used as a protective gas, only one exhaust pipe should be opened (for igniting the discharged radon gas). The inspection method can be to apply soap liquid in the gaps between the joints of the annealing furnace to see if there is any gas escaping; the areas where gas can easily escape are the area where the annealing furnace enters the pipe and the area where the pipe exits. Especially the sealing ring in this area is very easy to wear and needs to 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 radon protective gas, it is generally specified to be above 20kBar.

5. There is water vapor in the furnace.

On the one hand, check whether the raw materials on the furnace wall are dry. When installing the furnace 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 smls pipe entering the furnace, especially if there are holes on the top of the pipe, do not let water seep in, otherwise it will be damaged. Furnace atmosphere.