Differences between common stainless steel materials 201202301304316 and 400 series

You should consider the rust prevention, hardness, processing performance, etc. of hardware products. The rust prevention and heat resistance toughness of 201202301304316 are improved in turn.

202304316 corresponding density: 7.747.937.98

304 is the most common steel with good corrosion resistance, heat resistance, low temperature strength and mechanical properties. Deep stamping, bending and other room temperature processing properties are good, and will not harden after heat treatment. Household 1 or 2 kinds of Western tableware, sink, indoor piping, water heater, bathtub, boiler, auto parts (window cleaner, air return pipe), medical machinery, building materials, chemistry, food industry, textile industry, cheese industry, ship parts (non-magnetic, service temperature: -196 to 800 ℃)

304:C≤0.08,Ni8.00~10.00,Cr18.00~20.00,Mn≤2.0,Si≤1.0,S≤0.030,P≤0.045

304l:c ≤ 0.03 other elements are the same as 304

316 is a brand under the American Standard, which belongs to stainless, heat-resistant and corrosion-resistant steel. It is austenitic stainless steel, and the national standard is 0Cr17Ni12Mo2. It is a better stainless steel than 304. In seawater and other media, its corrosion resistance is better than 0Cr19Ni9, mainly pitting corrosion resistant material.

316:C≤0.08,Ni10.00~14.00,Cr16.00~18.00,Mo2.00~3.00,Mn≤2.0,Si≤1.0,S≤0.030,P≤0.035

Stainless steel 201304 difference

1. Specification: the commonly used stainless steel plates are divided into two types: 201 and 304. In fact, the composition is different. 304 is better in quality, but the price is expensive, and 201 is worse.

2. 201 is a kind of Ni steel and a substitute for 304 steel. It is magnetic after cold processing and is used for railway vehicles.

3. 304 is the most widely used stainless steel and heat-resistant steel. Used in food production equipment, general chemical equipment, nuclear energy, etc.

4. 201 has high manganese content, the surface is very bright with dark brightness, and the manganese content is high, which is easy to rust. 304 contains more chromium, and its surface is matte and does not rust. When the two are put together, there is a comparison. The most important thing is that the corrosion resistance is different. The corrosion resistance of 201 is very poor, so the price is much cheaper. And because 201 has low nickel content, its price is lower than that of 304, so its corrosion resistance is not as good as that of 304.

5. The difference between 201 and 304 is nickel. And the price of 304 is now relatively expensive, generally close to 50000 a ton, but 304 can at least ensure that it will not rust in the process of use. (liquid medicine can be used for experiments)

6. Stainless steel is not easy to rust because chromium rich oxide formed on the surface of the steel body can protect the steel body. Material 201 belongs to high manganese stainless steel, which is harder than 304, with high carbon and low nickel.

7. Different compositions (mainly distinguish 201 and 304 stainless steels from carbon, manganese, nickel and chromium)

Steel grade carbon (c) silicon (SI) manganese (MN) phosphorus (P) sulfur (s) chromium (CR) nickel (Ni) molybdenum (MO) copper (Cu)

AISI(304)≤0.08≤1.00≤2.00≤0.045≤0.0318-208-10

AISI(201)≤0.15≤1.005.5-7.5≤0.05≤0.0316-183.5-5.5

8. 400 series - Ferritic and martensitic stainless steel:

408: good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni.

409: the cheapest model, usually used as automobile exhaust pipe, is ferritic stainless steel (chromium steel).

410: martensite (high-strength chromium steel), good wear resistance, poor corrosion resistance.

416: sulfur is added to improve the processability of the material.

420: "cutting tool grade" martensitic steel, also used for surgical tools, can be made very bright.

430: ferrite, used for decoration, such as car accessories. Good formability, but poor temperature resistance and corrosion resistance.

440: high strength cutting tool steel, with slightly higher carbon content, can obtain higher yield strength after proper heat treatment, and the hardness can reach 58hrc, which is among the hardest stainless steels. The most common application example is "razor blade".

Magnetism

People often think that the magnet adsorbs stainless steel to verify its advantages and disadvantages and authenticity. If it is not adsorbed and non-magnetic, it is considered to be good and genuine; If the addict is magnetic, it is considered to be a fake. In fact, this is an extremely one-sided, impractical and wrong identification method.

There are many kinds of stainless steel, which can be divided into several types according to the organizational structure at room temperature:

1. Austenite type: such as 304, 321, 316, 310, etc;

2. Martensitic or ferritic type: such as 430, 420, 410, etc;

Austenite type is non-magnetic or weakly magnetic, while martensite or ferrite is magnetic.

Stainless steel, usually used as decorative tubesheet, is mostly Austenitic 304 material. Generally speaking, it is non-magnetic or weak magnetic, but magnetism may also occur due to chemical composition fluctuations caused by smelting or different processing states, but this cannot be considered as fake or unqualified. What is the reason?

As mentioned above, austenite is non-magnetic or weakly magnetic, while martensite or ferrite is magnetic. Due to component segregation during smelting or improper heat treatment, a small amount of martensite or ferrite structure in Austenitic 304 stainless steel will be caused. In this way, 304 stainless steel will have weak magnetism.

In addition, the microstructure of 304 stainless steel will also transform to martensite after cold processing. The greater the cold processing deformation, the more martensite transformation, and the greater the magnetism of the steel. Production of steel strips of the same batch number Φ 76 tube, no obvious magnetic induction, production Φ 9.5 pipe. The magnetic induction is more obvious because of the large bending deformation. The deformation of the square rectangular tube is larger than that of the round tube, especially the corner part. The deformation is more intense and the magnetism is more obvious.

In order to completely eliminate the magnetism of 304 steel caused by the above reasons, the stable austenite structure can be recovered through high-temperature solid solution treatment, so as to eliminate the magnetism.

In particular, the magnetism of 304 stainless steel caused by the above reasons is completely different from that of other stainless steels, such as 430 and carbon steel, that is to say, the magnetism of 304 steel always shows weak magnetism.

This tells us that if stainless steel has weak magnetism or no magnetism at all, it should be judged as 304 or 316 material; If it is the same as the magnetism of carbon steel, it shows strong magnetism, because it is judged to be not made of 304 material.

Why is stainless steel rusty?

When brown rust spots (spots) appeared on the surface of stainless steel pipes, people were surprised: they thought that "stainless steel is not rusty, rust is not stainless steel, and there may be a problem with the steel". In fact, this is a one-sided wrong view of the lack of understanding of stainless steel. Stainless steel will rust under certain conditions.

Stainless steel has the ability to resist atmospheric oxidation - that is, rust resistance, but also has the ability to resist corrosion in the medium containing acid, alkali and salt - that is, corrosion resistance. However, its corrosion resistance changes with the chemical composition of the steel itself, the interaction state, the service conditions and the type of environmental medium. For example, 304 steel pipe has absolutely excellent corrosion resistance in a dry and clean atmosphere, but if it is moved to the coastal area, it will soon rust in the sea fog containing a lot of salt; While 316 steel pipe performs well. Therefore, not any kind of stainless steel can resist corrosion and rust in any environment.

Stainless steel is a thin, solid and fine stable chromium rich oxide film (protective film) formed on its surface to prevent the continuous infiltration and oxidation of oxygen atoms, and obtain the ability to resist corrosion. Once for some reason, this film is constantly damaged, oxygen atoms in the air or liquid will continue to penetrate or iron atoms in the metal will continue to separate out, forming loose iron oxide, and the metal surface will continue to rust. There are many forms of damage to this surface facial mask, and the following are common in daily life:

1. There are dust containing other metal elements or attachments of dissimilar metal particles on the surface of stainless steel. In the humid air, the condensate between the attachments and stainless steel connects them into a micro battery, causing electrochemical reaction and damaging the protective film, which is called electrochemical corrosion.

2. Organic juice (such as melons and vegetables, noodle soup, phlegm, etc.) adhered to the surface of stainless steel constitutes organic acid in the presence of water and oxygen. For a long time, the corrosion of metal surface by organic acid.

3. The adhesion of stainless steel surface contains acid, alkali and salt substances (such as alkali water and lime water splashing on the decoration wall), causing local corrosion.

4. In polluted air (such as atmosphere containing a large amount of sulfide, carbon oxide and nitrogen oxide), when encountering condensate, sulfuric acid, nitric acid and acetic acid liquid points are formed, causing chemical corrosion.

The above conditions can cause the damage of the protective film on the surface of stainless steel and lead to corrosion. Therefore, in order to ensure that the metal surface is permanently bright and not corroded, we suggest:

1. The decorative stainless steel surface must be cleaned and scrubbed frequently to remove attachments and external factors that cause decoration.

2. 316 stainless steel should be used in coastal areas, which can resist seawater corrosion.

3. The chemical composition of some stainless steel pipes in the market cannot meet the corresponding national standards, and cannot meet the 304 material requirements. Therefore, it will also cause rust, which requires users to carefully choose products from reputable manufacturers

The so-called "stainless iron" refers to the recycling of scrap iron, lead, steel, etc. after secondary recycling and processing, through the "Zi" treatment. The traditional detection method is to use magnet, and this product is indistinguishable with the traditional method. Naturally, it is to deceive the world and cover up many engineering materials. Therefore, it entered one decoration site after another and boarded one luxury curtain wall after another. This name was born after the exposure of "focus interview" and accounts for about 65% of the market share, while the real national standard SUS304 stainless steel products have no market due to high prices.

At present, the price of "stainless steel" products plays an important role in the market because of its 65% share. At present, the price of national standard stainless steel products is about 20000 yuan per ton, the price of national standard 7075 aluminum alloy is about 16000 yuan per ton, and the price of "stainless steel" is only 5000-7000 yuan per ton; Further, the tensile strength of these three materials are: national standard stainless steel 530-620mpa, national standard 7075 aluminum alloy 540-560mpa, and "stainless iron" 160-180mpa. Obviously, the tensile strength of "stainless iron" is less than 1 / 3 of that of stainless steel, which is very easy to cause accidents.