202 stainless steel is one of the 200 series stainless steel, chemical composition of iron, manganese, aluminum, sodium, carbon, lime, carbon dioxide, bromine, density of 7.938 kg / cu dm. 202 stainless steel nickel content is generally below 4%, manganese content of about 8%, belongs to the low nickel high manganese type stainless steel.
202 stainless steel is often associated with 304 stainless steel, mainly because the two belong to the same austenitic structure, without magnetic, the appearance of the difference is not significant, the most important difference is the chemical element nickel content, resulting in the two in the performance and price of the huge difference.
Detailed description of the differences between the two, mainly the following.
1. Material composition is different: 202 stainless steel plate nickel content of about 4%, manganese content of about 8%, 304 stainless steel plate nickel content of about 8%, containing more than 18% of chromium.
2. Different corrosion resistance: 304 stainless steel plate in the chromium content is greater than 202, corrosion resistance is better than 202 stainless steel.
3. Application range is different: 304 stainless steel plate is mainly used in food processing, storage and transportation, medical appliances, household items, auto parts, bellows, etc., while 202 stainless steel plate is used in architectural decoration, public facilities, municipal engineering, highway guardrails, shopping malls, glass handrails, etc.
Due to the difference in nickel content, resulting in the cost of 202 stainless steel plate is much lower than 304 stainless steel plate, so the market appeared with 202 stainless steel plate posing as 304 stainless steel plate, to know the 200 series of stainless steel in corrosion resistance and toughness is far inferior to the 300 series, if the wrong purchase and use, after which there will be a great hidden danger.
So how to distinguish 202 stainless steel and 304 stainless steel?
Observation and touch: close observation of stainless steel surface, 304 stainless steel plate color saturation bright, 202 stainless steel plate color dark, low color saturation; touch feeling, 304 stainless steel plate feel smooth, 202 stainless steel plate feel a little rough.
Chemical identification method: buy professional stainless steel material identification potion, drop on the surface of stainless steel, by showing the color contrast color card, to determine the stainless steel material.
Friction spark identification method: stainless steel on a high-speed rotating grinding machine for friction, stainless steel friction sparks will be different because of the composition of different trace elements, you can identify the approximate content of the chemical composition from the number of sparks, shape bifurcation and other differences, of course, this method requires certain conditions and professional skills, non-professionals or recommend the use of observation touch and chemical identification methods.
Many people are concerned about whether 202 stainless steel plate will rust, in fact, whether stainless steel rust, mainly by the formation of chromium-nickel oxide film, oxide film by isolating oxygen to avoid rust. 202 stainless steel plate to manganese instead of nickel, nickel content is low, so the corrosion resistance is poor, in use to pay attention to the use of scenes, avoid sharp things bump, scratch, to prevent damage to the surface of the oxide film.