Why is the Alloy Pipe Magnetic?
Date:2022-03-14View:542Tags:alloy pipe
People often think that magnets attract alloy pipes to verify their pros and cons and their authenticity. If they do not attract and have no magnetism, they are considered to be good and genuine; those who attract magnets are considered to be counterfeit and fake. In fact, this is an extremely one-sided, unrealistic and wrong identification method.
There are many kinds of alloy pipes, which can be divided into several categories according to the structure at room temperature:
1) Austenitic type: such as 304, 321, 316, 310, etc.;
2) Martensite or ferrite type: such as 430, 420, 410, etc.;
The austenitic type is non-magnetic or weakly magnetic, and the martensite or ferrite is magnetic. Most of the alloy tubes usually used as decorative tube sheets are austenitic 304 materials, which are generally non-magnetic or weakly magnetic, but may also appear magnetic due to fluctuations in chemical composition or different processing states caused by smelting, but this cannot be considered Is it fake or substandard, what is the reason?
As mentioned above, austenite is non-magnetic or weakly magnetic, while martensite or ferrite is magnetic. Due to component segregation or improper heat treatment during smelting, a small amount of martensite or iron in austenitic 304 alloy pipes will be caused. Body tissue. In this way, the 304 alloy pipe will have weak magnetism; in addition, the 304 alloy pipe will be transformed into martensite after cold working more big. Like a batch of steel strips, Φ76 tubes are produced without obvious magnetic induction, and Φ9.5 tubes are produced. Due to the large deformation of the bending, the magnetic induction is more obvious. The deformation of the square tube is larger than that of the round tube, especially the corner part, the deformation is more intense and the magnetic force is more obvious.
In order to completely eliminate the magnetic properties of 304 steel caused by the above reasons, the stable austenite structure can be restored by high-temperature solution treatment, thereby eliminating the magnetic properties.
In particular, the magnetic properties of 304 alloy pipes caused by the above reasons are not at the same level as alloy pipes of other materials, such as 430 and carbon steel, that is to say, the magnetic properties of 304 steel always show weak magnetic properties. . This tells us that if the alloy pipe has weak magnetism or no magnetism at all, it should be judged as 304 or 316 material; if it is the same as carbon steel, it shows strong magnetism, because it is judged as not 304 material.
Linkedin
