On 2018-08-08 14:48:54
Heat treatment characteristics of aluminum tube
Aluminum tube is a kind of non-ferrous metal tube, which is made of pure aluminum or aluminum alloy by extrusion and processing. Aluminum tube is widely used in automobile, ship, aerospace, aviation, electrical, agriculture, electromechanical, home and other industries. It is a kind of high-strength duralumin, which can be strengthened by heat treatment. It has medium plasticity in annealing, rigid quenching and hot state, good spot welding performance. When gas welding and argon arc welding are used, the aluminum tube tends to form intergranular cracks; after quenching and cold work hardening, the machinability of the aluminum tube is good, but it is not good in annealing state. Because of the low corrosion resistance, anodizing and painting methods are often used or aluminum coating is added on the surface to improve the corrosion resistance. It can also be used as mold material. Aluminum tube has excellent bending performance, is easy to install and move, and is suitable for industrial production of thin-wall copper aluminum tube welding technology, which is known as the world-class problem, and is the key technology of air conditioner connecting tube aluminum instead of copper.
Let's talk about the characteristics of aluminum tube after heat treatment:
As we all know, for steels with high carbon content, high hardness and low plasticity are obtained immediately after quenching. However, for aluminum alloy, after quenching, the strength and hardness do not increase immediately, and the plasticity does not decrease, but increases. However, the strength and hardness of the quenched alloy will be significantly improved, while the plasticity will be significantly reduced. The phenomenon that the strength and hardness of Quenched Aluminum alloy increase with time is called aging. Aging can occur at room temperature, which is called natural aging, or at a temperature range higher than room temperature (such as 100-200 ℃), which is called artificial aging.
So how to identify what is the real heat-treated aluminum pipe?
Use open fire to light the pipe. The real aluminum-plastic pipe is made by ultrasonic lap welding or hydrogen arc welding. Its interface is very close. The aluminum sheet that has been heat treated after the pipe is ignited by open flame will not fall off. However, the fake aluminum-plastic pipe and other combined pipes will fall off after being ignited because the aluminum sheet is not welded and its interface is not close.
Two, look at
Through the observation and hand touch of the surface characters and inner and outer surface of the aluminum tube.
1. The words on the surface of genuine aluminum pipes are generally printed by imported ink jet printing, with clear handwriting, and the general marks such as trademark identification, manufacturer, address and even telephone are clear and true; the words on the surface of fake and inferior aluminum pipes are mostly printed by ordinary printing machine, with fuzzy handwriting, and the manufacturer and logo are generally unknown or not marked.
2. The authentic aluminum tube is made of high-quality raw materials, with high process accuracy, smooth and smooth surface and inner layer feel, and flat without speckles; while the fake aluminum plastic tube products are relatively poor due to Jerry building.
3. The wall thickness of the authentic aluminum-plastic pipe mouth and aluminum strip is uniform, the aluminum tube is closely combined, and the quality and thickness of the pipe and aluminum strip can meet the relevant national standards; the wall thickness deviation of the fake and inferior products is large, the aluminum sheet is thin, and the gap of the aluminum tube lap joint is large.
Use pipe shear to cut the aluminum pipe into strip shape according to spiral shape, and peel off the aluminum pipe layer and PE layer by hand. The real aluminum plastic pipe is a 5-layer composite structure, its aluminum layer and PE layer are closely bonded, and it is not easy to separate the aluminum pipe layer and PE layer by hand; while the aluminum layer and PE layer of the fake and inferior products are not closely bonded due to the Jerry built materials, which is very easy to peel off.
The pressure resistance of aluminum tube is tested by a small pressure pump. The explosion internal pressure of the real aluminum plastic pipe is high, which can generally meet or exceed the requirements of the relevant national specifications; while the explosion internal pressure of the fake and inferior products is generally low or even low, which is difficult to meet the use requirements.