One, the use of stainless steel identification agent to identify
Stainless steel identification agent is used to detect the nickel content of steel to distinguish which series of stainless steel. There are a variety of specifications for rapid detection of 200 series, 300 series, 400 series and other stainless steel. Stainless steel identification agent is very simple to use, directly drop in the stainless steel plate can be, stainless steel identification agent is generally in 2-3 minutes or so can be out of the effect of different colors correspond to different models of stainless steel materials.
10 seconds or so red for ordinary 201 stainless steel (manganese exceeds the standard); 50 seconds or so red for authentic 201 stainless steel (manganese exceeds the standard); 1 minute or so red for the 202 stainless steel (manganese exceeds the standard); 301 stainless steel in 2-3 minutes will become red, but the color is very light, you need to look at it carefully; if the color of the color in 3 minutes without any change, the bottom of the color is slightly darker, this is the is authentic SUS304 stainless steel. General stainless steel identification agent is equipped with a contrast color card, identification results directly compared to know the model of stainless steel plate, very convenient.
Second, through the magnetic identification of 304 stainless steel
In the stainless steel market, there are still misunderstandings about the understanding of 304 stainless steel. Some people think that using a magnet to suck stainless steel, can suck on is stainless steel, can not suck is stainless steel, good stainless steel are not magnetic. However, on this point of view, the following I will make a judgment for you, in the end how to identify the 304 stainless steel through this magnetic properties.
First of all, we know that 304 stainless steel belongs to the austenitic type, but the austenitic type is non-magnetic or weakly magnetic, so we will think that the good stainless steel is not magnetic. However, people lack of neglect is 304 stainless steel in the smelting process caused by fluctuations in its chemical composition or processing state at the same time there may be magnetic, but this can not be considered to be counterfeit or unqualified products; in addition 304 stainless steel after cold working, the organizational structure will be transformed to martensite, cold working deformation degree is greater, the more martensite transformation, the greater the magnetism of the steel.
On the contrary, the quality of the second point of the 200 series stainless steel, it is likely that the non-magnetic, thus determining that it is the real stainless steel, it is very wrong. In particular, due to the above reasons caused by the magnetic 304 stainless steel, and other materials of stainless steel magnetic is not the same level, that is to say, the magnetic 304 steel is always weakly magnetic.
This tells us that if the stainless steel with weak magnetism or completely non-magnetic, should be identified as 304 or 316 materials; if the same with the magnetism of carbon steel, showing strong magnetism, due to the judgment is not 304 materials.
Third, with copper sulfate identification
Remove the oxidized layer on the steel, put a drop of water, with copper sulfate rub, after rubbing, such as no color change, generally for stainless steel; such as purplish-red, non-magnetic high-manganese steel, magnetic general for ordinary steel or low alloy steel.
For special properties of steel, we also need to take the following three ways to identify.
Cold-worked chromium-nickel stainless steel, such as magnetic, can take a small piece of red in the fire to let it cool naturally or into the water (annealed), generally speaking, after annealing the magnetic properties will be significantly weakened or completely disappeared. But some chromium-nickel stainless steel, such as Cr18Ni11Si4AlTi steel and Cr21Ni5Ti steel, because of the steel contains more ferrite elements, its internal organization has a considerable part of ferrite. Therefore, even in the state of hot working there are magnetic.
Four, grinding flower identification
Grinding flower identification is the stainless steel in the grinder, watch its sparks. If the spark is streamlined, and there are more dense knots, that is, for the higher manganese-containing high manganese steel or manganese-nitrogen steel; such as no knots that is chromium steel or chromium-nickel stainless steel.
Fifth, chemical characterization method of identification
Chemical characterization method is to identify whether the magnetic stainless steel containing nickel is an identification method. The method is to dissolve a small piece of stainless steel in the king of water, with clean water to wash down the acid, add ammonia neutralization, and then gently injected into the nickel reagent. If there is a red fluffy material floating on the liquid surface, that is, stainless steel contains nickel; if there is no red fluffy material, that is, proof of stainless steel without nickel (but due to the low content of nickel in stainless steel, generally only a few percent, nickel content is not easy to reveal or determine how much, generally have to be used as a standard sample experiment many times in order to grasp).
304 stainless steel is a common material in stainless steel, density 7.93 g/cm3, the industry is also called 18/8 stainless steel. High temperature resistance of 800 ℃, with good processing performance, high toughness, widely used in industrial and furniture decoration industry and food medical industry.
The common labeling methods in the market are 0Cr18Ni9, SUS304, of which 0Cr18Ni9 generally indicates that the national standard production, 304 generally indicates that the ASTM standard production, SUS 304 indicates that the Japanese standard production.
304 is a general-purpose stainless steel, which is widely used in the production of equipment and machine parts requiring good overall performance (corrosion resistance and molding). In order to maintain the corrosion resistance inherent in stainless steel, the steel must contain more than 18% chromium, more than 8% nickel content. 304 stainless steel is a grade of stainless steel produced in accordance with the American ASTM standard.
Baidu Encyclopedia-304 Stainless Steel