How to distinguish 202 and 304 stainless steel?
Time : 2023-01-17
How to distinguish 202 and 304 stainless steel?

Chemical composition

202 stainless steel is one of the 200 series stainless steels. The chemical composition is iron, manganese, aluminum, sodium, carbon, lime, carbon dioxide, bromine, and the density is 7.938 kg/cubic decimeter. The nickel content of 202 stainless steel is generally below 4%, and the manganese content is about 8%, which belongs to low nickel and high manganese stainless steel.

202 stainless steel is often associated with 304 stainless steel, mainly because both belong to the austenitic structure, without magnetism, and there is little difference in appearance. The most important difference lies in the content of the chemical element nickel, which causes the two to be in Huge difference in performance and price.

1. The material composition is different: 202 nickel content is about 4%, manganese content is about 8%, 304 nickel content is about 8%, and it contains more than 18% chromium.

2. Different corrosion resistance: The chromium content in 304 stainless steel is greater than 202, and its corrosion resistance is better than 202.

3. The scope of application is different: 304 is mainly used in food processing, storage and transportation, medical appliances, household products, auto parts, corrugated pipes, etc., while 202 is used in architectural decoration, public facilities, municipal engineering, highway guardrails, shopping malls, glass handrails wait.

Due to the difference in nickel content, the cost of 202 is much lower than that of 304. Therefore, 202 is used to pretend to be 304 in the market. You must know that 200 series stainless steel is far inferior to 300 series in terms of corrosion resistance and toughness. If you buy and use it properly, there will be great hidden dangers in the future.

How to distinguish 202 stainless steel and 304 stainless steel?

Observation and touch: Observing the stainless steel surface at close range, the color saturation of 304 stainless steel is bright, while the color saturation of 202 stainless steel is dark and the color saturation is low; the touch feeling is that 304 stainless steel feels smooth, while 202 stainless steel feels rough.

Chemical identification method: Purchase professional stainless steel material identification potion, drop it on the surface of stainless steel, and judge the stainless steel material by comparing the displayed color with the color card.

Friction and spark identification method: Put stainless steel on a high-speed rotating grinder for friction. The sparks generated by stainless steel friction will be different due to different trace element compositions. The approximate chemical composition can be identified from the number and shape of the sparks. Of course, this method requires certain conditions and professional skills. Non-professionals still recommend using the method of observation, touch and chemical identification.

Whether stainless steel is rusted or not is mainly determined by the oxide film formed by chromium and nickel. The oxide film prevents corrosion by isolating oxygen. 202 stainless steel uses manganese instead of nickel, and the nickel content is low, so the corrosion resistance is poor. Pay attention to the usage scene when using it, avoid bumping and scratching with sharp objects, and prevent the oxide film on the surface from being damaged.

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