How to Identify the Quality of 304 Stainless Steel Pipes?

304 stainless steel pipes can be seen everywhere in our lives, but the stainless steel pipe industry is a mixed bag. Some bad 304 stainless steel pipe manufacturers even mix the real and fake 304 stainless steel pipes. The real 304 stainless steel pipes cannot be identified by the naked eye, so many friends who want to buy 304 stainless steel pipes are discouraged. At present, the stainless steel pipes on the market can be roughly divided into 304, 201, 316 stainless steel and other types. When buying pipes, do you know how to identify 304 stainless steel pipes?

How to identify 304 stainless steel pipes?

1. Use magnets to identify 304 stainless steel pipes

Ordinary stainless steel pipes have strong magnetism, but 304 stainless steel pipes are non-magnetic or weakly magnetic. Take a magnet close to an ordinary stainless steel pipe and a 304 stainless steel pipe, and you can clearly feel the difference in magnetic force between them, and you will know which stainless steel pipe is the real 304 stainless steel pipe.

2. Identification with copper sulfate

Remove the oxide layer on the steel, put a drop of water on it, and rub it with copper sulfate. If it does not change color after rubbing, it is generally stainless steel; if it turns purple-red: it is non-magnetic and high-manganese steel, and magnetic ones are generally ordinary steel or low-alloy steel.

For steel grades with special properties, we also need to adopt the following three methods for identification. Cold worked chromium-nickel stainless steels, if magnetic, can be cooled naturally by burning small pieces in a fire or placing them in water (annealing). Typically, after annealing, the magnetic properties are significantly reduced or completely eliminated. However, some chromium-nickel stainless steels contain more ferrite elements, and a considerable part of their internal development organization is ferrite. Therefore, it is magnetic even in the hot-worked state.

3. Test solution identification

Stainless steel testing liquid: also called stainless steel pipe testing solution. First, make sure there is no stain on the surface of the 304 stainless steel pipe. After grinding off the surface coating, add a drop of testing liquid to remove the coating. Observe the color change of the 304 stainless steel pipe in the test area, and compare the color of the 304 stainless steel pipe or the time it turns red to make a judgment.

4. Grinding identification

The method of identifying grinding sparks is to grind it on a grinding machine and observe the sparks. If the sparks are streamlined and the knots are dense, it is high manganese steel or manganese-ammonia steel with a high manganese content; if there are no knots, it is chrome steel or nickel-plated stainless steel. Observation through sparks: The sparks and hardness during cutting or welding of 304 stainless steel pipes can also distinguish the quality of stainless steel pipe materials.

5. Identification by steel stamp

Now many regular stainless steel manufacturers will have corresponding steel stamps when producing 304 stainless steel pipes. The steel stamps generally contain the material of the stainless steel pipe and the brand of the manufacturer. 304 stainless steel pipes can be identified by the steel stamps on the stainless steel.

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