How is 304 stainless steel sheet tested? - Shandong Jiugang Tisco Steel Co., Ltd.

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How is 304 stainless steel sheet tested?

304 stainless steel products greatly facilitate daily life, we will also encounter some of the substandard, counterfeit manufacturers, with fake 304 stainless steel plate or non-304 stainless steel plate to fraudulent 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 of the market is currently the appropriate way to label the key has “SUS304” or “304”, to avoid the shop to use ” 304 stainless steel plate is a common material in stainless steel, with good production and processing characteristics, high ductility characteristics. Today, TISCO steel to talk about how to identify the authenticity of 304 stainless steel plate.


A, the choice of stainless steel assessment agent to identify

Stainless steel assessment agent is used to test the nickel content of stainless steel plates 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. The 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 up and down the actual effect, not the same colour matching the different types of stainless steel materials. 10 seconds up and down the red for the general 201 stainless steel plate; 50 seconds up and down the red for the pure 201 stainless steel; 1 minute up and down the red for 202 stainless steel; 301 stainless steel in 2-3 minutes. The 301 stainless steel plate in 2-3 minutes will be red, but the colour is very light, you must look carefully; if the colour does not have all the changes within 3 minutes, the bottom colour is slightly darker, this is considered pure SUS304 stainless steel plate. General stainless steel assessor are equipped with a colour 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 lack ignore the point is 304 stainless steel plate in the whole process due to the smelting plant led to its composition fluctuation or production processing situation is not in addition likely to occur magnetic, but this can not feel counterfeit or substandard products; In addition, 304 stainless steel plate through cold drawing, the organization structure will also be converted to martensite, cold drawing deformation value is greater, the more austenite conversion, the greater the steel magnetism. In turn, the quality of the next bit of 200 series stainless steel, it is likely that no magnetic, thus judging it to be value for money stainless steel, it is a big mistake. Especially to clearly put forward is, because of the above cause of 304 stainless steel magnetism, and other materials of stainless steel magnetism thoroughly is not the same level, in other words 304 stainless steel magnetism from the beginning to indicate the weak magnetism. This informs 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, as identified as and not 304 materials.


Three, 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 loss of colour, 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, can be used in 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 steels, 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 tissue. Therefore, even in the case of heat treatment is also magnetic.


Four, scratch identification

Scraping identification is to put the stainless steel in the grinder 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 together, and then gently introduced nickel experimental reagent. If the level in the liquid level of bright red velvet emulsion, that is, the stainless steel with nickel; such as no bright red velvet emulsion, that is, to confirm that 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 sense of identification of the way, at this stage is extremely unsound, some may be incorrect, there are also many physical changes, but also only learn to know and do not know why, subject to further discussion.



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