When the steel tube is annealed online, the oxide layer will appear. But Forever will not.
First, let us first understand the hazards of oxide.
1. Cause the loss of metal material: the oxide layer produced when the metal is heated will cause the loss of metal material. In general, 0.5%~3.0% of the metal is burned out every time the steel pipe is heated. In severe cases, the burning rate can even reach 3%.
2. Influencing the surface quality of steel pipe: During annealing heat treatment, if the oxide scale on the pipe is not cleaned up, once put into use, there will be pits on the surface of the pipe, it will become waste. Oxidation layer on the surface of the steel pipe will lead to uneven internal structure and physicochemical properties.
3. Reduce the service life of steel pipe: because of the high hardness of oxide layer, the oxide layer will accelerate the wear of steel pipe, thereby reducing the service life of steel pipe, but also affect the life of steel pipe annealing furnace.
Therefore, it is of great significance to reduce and prevent metal oxidation, which can not only improve the quality and service life of metal materials, but also reduce the cost of investment. First of all, the problem of oxidation should be solved by using less and no oxidation heating.
For on-line steel pipe annealing furnace, according to the heating environment factors which affect the oxide scale formation, corresponding measures are taken in the furnace process to reduce the oxide scale formation.
The main measures are as follows:
1. Fast heating. Under the premise of ensuring the quality of castings, rapid heating can be adopted.
The annealing furnace can shorten the heating time, especially the residence time at high temperature.
2. Control the properties of heating furnace gas. Under the condition of complete combustion, the air intake into the furnace should be strictly controlled to minimize excess air as much as possible, because excess air will accelerate oxidation, and there should be excessive reductive gas in the furnace.
3. During holding process, the on-line annealing furnace of steel pipe should maintain a small positive pressure, especially in the high temperature holding stage, which can prevent cold air from entering the furnace.
Quick heating has many advantages, which can greatly increase the furnace temperature and send metal materials at room temperature directly to the heating furnace at high temperature.
Generally, the furnace temperature is raised to 1400-1500 degrees Celsius, and some even to 1600 degrees Celsius, because the temperature (temperature difference between furnace and metal surface) is more than 3-4 times than the general, heating time is greatly shortened. Rapidly heated pipes have the advantage of small grain size and high toughness because of the short time at high temperatures and less accumulation of intergranular nonmetallic impurities.
Here we recommend Forever pipe heat treatment furnace for annealing the pipes, the pipes will not have problem of bending, crack and oxidation decarbonization.
Contact person: Hailee Ma
Phone: 0086-18932783253(whatsapp, wechat)
Specialist of bar heat treatment furnace in China; Glad to be your business partner in induction heating field.
Post time: 09-12-2018