site logo

How to identify the 304 stainless steel plate stainless steel coil stainless steel products we buy is not fake?

How to identify the 304 stainless steel plate stainless steel coil stainless steel products we buy is not fake?

Time:2022-03-16 Source:WUXI JIANO SPECIAL STEEL CO.

304 stainless steel sheet is widely used in various industries because of its excellent performance. How to identify the stainless steel model is also a matter of concern. Stainless steel plate is an indispensable material in home decoration. And 304 stainless steel material as the leading stainless steel material, loved by people. 304 material is known as 18/8 stainless steel in the industry, its rust resistance is not only more prominent than the 200 series, and can withstand nearly 800 times the corrosion ℃ high temperature.


1, using 304 stainless steel plate identification agent for identification.

(1) Stainless steel identification agent is used to detect the nickel content of the steel and distinguish which series of stainless steel. There are a variety of specifications to quickly detect 200 series, 300 series, 400 series stainless steel. Stainless steel identification agent is very simple to use. It can be dropped directly on the stainless steel plate. The effect of stainless steel identification agent can be achieved in about 2-3 minutes. Different colors correspond to different types of stainless steel materials.

(2) Ordinary 201 stainless steel turns red in 10 seconds; real 201 stainless steel turns red in about 50 seconds; 202 stainless steel turns red in about 1 minute; 301 stainless steel will turn red in 2-3 minutes, but the color is very light and needs to be carefully observed; if there is no color change in 3 minutes and the base color is slightly darker, this is authentic SUS304 stainless steel.

(3) stainless steel identification agent is generally equipped with a comparative color card. Through the direct comparison of identification results, you can know the model of stainless steel plate, very convenient.

2, 304 stainless steel by magnetic identification.

(1) First, we know that 304 stainless steel belongs to austenitic type, but austenitic type is non-magnetic or weakly magnetic, so we would think that good stainless steel is non-magnetic. However, people ignore that 304 stainless steel may be magnetic due to fluctuations in chemical composition during smelting or different processing states, and cannot be identified as counterfeit or unqualified products; in addition, 304 stainless steel will transform its microstructure to martensite after cold working. The greater the cold working deformation, the more martensite phase change, the higher the magnetic energy of the steel.

(2) In contrast, the lower quality 200 series stainless steel is likely to be non-magnetic, so it is a big mistake to judge it as a real stainless steel. In particular, it should be noted that the magnetic properties of 304 stainless steel caused by the above reasons are not at the same level as the magnetic properties of stainless steel of other materials, that is, the magnetic properties of 304 steel always show weak magnetic properties. This tells us that if the stainless steel has weak magnetism or no magnetism at all, it should be identified as 304 or 316 material; if it has the same magnetic properties as carbon steel, it shows very strong magnetism because it is not 304 material.

3. Identified by copper sulfate. Remove the oxide layer on the steel, put a drop of water and wipe it with copper sulfate. If the wipe does not change color, generally for stainless steel; such as purple-red, non-magnetic for high manganese steel, magnetic generally for ordinary steel or low-alloy steel.

4. Identification of the grinding pattern. The identification of the grinding pattern is to grind the stainless steel on the grinder and observe its sparks. If the sparks are linear and the number of knots is high, it is high manganese steel or manganese nitrogen steel with high manganese content; if there are no knots, it is chromium steel or chromium-nickel stainless steel.

5, chemical characterization identification.

(1) Chemical characterization method is a way to identify whether the magnetic stainless steel contains nickel. The method is to dissolve a small piece of stainless steel in aqua regia, dilute the acid solution with purified water, add ammonia to neutralize, and then gently inject the nickel reagent.

(2) If there is red fluffy material floating on the surface of the liquid, indicating that there is nickel in stainless steel; if there is no red fluffy material, proving that the stainless steel does not contain nickel (but because the nickel content of stainless steel is low, generally only a few percent, the nickel content is not easy to reveal or determine, so it is generally necessary to use the specimen several times to master the test).

The following are five ways to identify the authenticity of 304 stainless steel sheet. A better way to correctly distinguish between stainless steel grades is to go to the relevant testing units for testing and judgment. This is the basic method to distinguish the grade and quality of stainless steel. Each stainless steel has a different function, and this steel can be found everywhere in our lives.