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How to identify whether the 304 stainless steel sheet you buy meets international

How to identify whether the 304 stainless steel sheet you buy meets international standards?

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

304 stainless steel products greatly facilitate daily life, we will also encounter some substandard, counterfeit manufacturers in daily life, with fake 304 stainless steel plate or non-304 stainless steel plate to defraud customers, to customers with immeasurable damage. When you have to buy 304 stainless steel products, you should recognize the product labeled model, at this stage, the current market appropriate labeling way Key has “SUS304” or “304”, to avoid the store to use ” SVS304″, “DUS304” and so on to generalize. 304 stainless steel is a common material in stainless steel, with good production and processing characteristics, ductility and high characteristics. But in recent years because of the flood of low-nickel carbon steel, stainless steel sales market disorder, coupled with the customer with the human eye can not differentiate between the raw material type of stainless steel, very easy to be the store’s propaganda planning fraud; today, Wuxi JiaNuo special steel to talk about how to identify the authenticity of 304 stainless steel plate.


A, the choice of stainless steel evaluation agent to identify

Stainless steel evaluation agent is used to test the nickel content of stainless steel plate to distinguish which series of stainless steel. There are a variety of specifications for the rapid detection of 200 series products, 300 series products, 400 series products and other stainless steel. Stainless steel evaluation agent is very simple, immediately drop in the stainless steel plate can be, stainless steel evaluation agent generally in 2-3 minutes on the actual effect, not the same color match the different types of stainless steel materials. 10 seconds up and down red for general 201 stainless steel; 50 seconds up and down red for pure 201 stainless steel; 1 minute up and down red for 202 stainless steel; 301 stainless steel in 2-3 minutes. 301 stainless steel in 2-3 minutes will be red, but the color is very light, you must look carefully; if the color does not have all the changes in 3 minutes, the bottom color slightly darkened, this is considered pure SUS304 stainless steel. General stainless steel assessor are equipped with a color card comparison table, identification results immediately compared to the stainless steel plate can understand the model specifications, very convenient.

Second, according to the magnetic identification of 304 stainless steel

We know that 304 stainless steel belongs to the martensitic type, but the martensitic type is non-magnetic or weak magnetic, so people will feel that good stainless steel is not magnetic. However, we ignore the point is 304 stainless steel in the smelter due to the whole process leading to its composition fluctuations or production processing is not in addition likely to occur magnetic, but this can not feel counterfeit or substandard products; In addition, 304 stainless steel through cold drawing, the organizational structure will also be converted to martensite, the greater the value of cold drawing deformation, the more austenite conversion, the greater the magnetic properties of steel. In turn, the quality of the next 200 series of stainless steel, it is likely that there is no magnetic, so that it is judged to be a good value for money stainless steel, it is very wrong. Especially to clearly put forward is that the magnetic properties of 304 stainless steel due to the above, and other materials of stainless steel magnetism thoroughly is not the same level, in other words, the magnetic properties of 304 steel from the beginning to indicate the weak magnetic properties. This tells you that if the stainless steel with weak magnetism or no magnetism, should be identified as 304 or 316 materials; if the same as the carbon steel magnetism, indicating a strong magnetic, because the identification is not 304 materials.

Third, with sodium thiosulfate identification

Remove the air oxide layer on the stainless steel plate, put on a drop of water, with sodium thiosulfate rub, rub, such as no color loss, generally for stainless steel; such as dark purple, non-magnetic for the carbon steel, magnetic general steel or high alloy steel. For the unique characteristics of steel grades, we also need to use the following three methods to carry out the identification. Cold-drawn chromium-nickel stainless steel, if magnetic, a small piece of red in the fire to let it certainly cooling or put into the water (quenching), generally speaking, after quenching the magnetic will be significantly weaker or completely fade. But there are some chromium-nickel stainless steel, such as Cr18Ni11Si4AlTi steel and Cr21Ni5Ti steel, because the steel with more metallurgical tissue elements, which in the institution there is a very part of the metallurgical organization. Therefore, even in the case of heat treatment is also magnetic.

Four, scratch identification

Scraping identification is the stainless steel in the polishing machine grinding, watching its fire. If the fire is streamlined, and there are more dense nodal flowers, that is, high manganese carbon steel or manganese nitrogen steel; such as no nodal flowers that is manganese steel or chromium-nickel stainless steel.

Five, through the chemical determination method to identify

Organic chemical determination method is to identify the magnetic stainless steel is not a method of identification of nickel. Its way is, a small piece of stainless steel melted in aqua regia, with purified water will acid desalination, add sodium hydroxide in the combined, and then gently introduced nickel experimental reagent. Such as in the level of the transfer of bright red velvet emulsion, that is, the stainless steel with nickel; such as no bright red velvet emulsion, that is, to confirm the stainless steel without nickel.

Through the above several types of identification methods show that the identification of stainless steel by sense, not only to use several types of way comprehensive experiments, and its experimental results only clear a certain type of stainless steel, not clear steel with which aluminum alloy element and the actual composition. Thus, the way of sensory identification, at this stage is extremely unsound, some may be incorrect, there are many physical changes, but also only learn to know and do not know why, subject to further discussion.