When we use the a500 rectangular tube, sometimes we find that the brightness of the surface is not enough, which will not only affect the appearance of the a500 rectangular tube, but also affect its use effect. So what are the factors that affect the surface brightness of a500 rectangular tube?

1. The oil content in the emulsion is too high. The emulsion used in the cold rolling mill is composed of water, emulsifier and oil. The emulsion has both cooling and lubricating effects, and the oil will crack into carbon at high temperature. If these carbons are not removed in time, they will accumulate on the surface of the a500 rectangular tube and form indentations after being flattened by a flat engine. Therefore, the oil content in the emulsion is one of the main factors affecting the quality of a500 rectangular tube.

2. There is a lot of carbon black attached to the inner wall of the protective cover. Because the oil content in the emulsion is very high, carbonization will occur after annealing in the bell furnace. Then, carbon is deposited on the inner wall of the protective cover, and as the number of annealing heats increases, carbon black increases. If it is not removed in time, the carbon black will be scattered on other steel coils, and after processing, the carbon will adhere to the surface of the a500 rectangular tube.

3. Insufficient purging volume of annealing furnace and poor recovery performance. Due to the purging of the maintenance gas break in the annealing furnace, it is only about 20-25m3/h. Therefore, it is often difficult to blow off the gasified oil stains during the heating process, resulting in black bands appearing on the outer ring of the steel coil, polluting the outer surface of the a500 rectangular tube. In addition, because the hydrogen content of this maintenance gas is generally only 3% to 6%, and most of it is nitrogen, the carbon content is too large to be recovered. And because nitrogen is an inert gas, not only cannot combine with the evaporated gas, so it can only be blown out, and the deposition of carbon cannot be avoided.

4. The furnace table and convection plate are not cleaned. Some carbon black, oil stains, dust, etc. will also accumulate on the surface of the furnace table and convection plate. If the furnace is not cleaned before loading, the carbon black, oil stains and dust will also be scattered on the steel coil, affecting the appearance quality.

5. The emulsion on the surface of the a500 rectangular tube cannot be blown off cleanly. There is no purge device at the exit of the cold rolling mill, which is specially used to purge the residual emulsion and oil on the surface of the a500 rectangular tube.

A500 rectangular tube is a steel pipe rolled by strip steel through process treatment. According to its production process, it is divided into seamless a500 rectangular tube and welded a500 rectangular tube. Seamless a500 rectangular tube is formed by extruding seamless pipe. Widely used in machinery manufacturing, construction industry, metallurgical industry, agricultural vehicles, agricultural greenhouses, automobile industry, railway, highway guardrail, container skeleton, furniture, decoration and steel structure fields, etc.