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 Common sense of stainless steel


Definition of stainless steel

Stainless steel is a kind of high-alloy steel that can resist corrosion. It has a beautiful surface and does not need to undergo surface treatment such as color plating or paint. Therefore, many machinery factories often do not do any paint treatment in order to show that they are stainless steel, while black materials ( The so-called black material is the name of general steel) must be anti-rust treatment.

Simple classification of stainless steel

Stainless steel can be roughly divided into three categories: 200 series, 300 series and 400 series. Among them, 300 series is the most commonly used, and 200 series and 400 series are substitutes for 300 series to a certain extent. Strictly speaking, 400 series is not called stainless steel. , called stainless iron, because it does not contain nickel, so it can be attracted by a magnet. The 200 series and 300 series are made of nickel, so they are non-magnetic and cannot be absorbed by iron.
304 is the most common variety in the 300 series, so generally the price trend of the entire stainless steel can be judged from the price change of 304. The 200 series contains less nickel, the 400 series contains no nickel, and the 300 series contains the most nickel, so the 300 series is most affected by the price of nickel.
The 300 series can be simply divided into 304, 304L, 316, 316L, 321, 309S, 310S, etc. The basis for the distinction is that the contents of various metal elements are different, and the characteristics of stainless steel with different contents are also different. The difference between 304 and 304L is that The carbon (C) content is different, the one with L means low carbon content, also called low carbon, and the difference between 316 and 316L is the same.


Morphological classification of stainless steel

Stainless steel can be divided into five categories: coils, plates, profiles, steel pipes and parts, the most important being coils and plates. Profiles are materials of various shapes made of plates, including angle steel, flat steel, I-beam, and channel steel. Steel pipe mainly refers to seamless steel pipe, and the opposite of seamless steel pipe is welded pipe. The difference lies in whether it is formed at one time. Components mainly refer to elbows and flanges and other small things.
The coiled material and the plate are actually the same, but the factory form is different. The coiled material is a roll, and the plate is a sheet. If the factory is a plate, it is also called the original plate. It is usually a thick plate because it is very thick. If it is too large, it cannot be rolled, generally it cannot be rolled if it is more than 16mm.
There are rolls and plates, and most of the time it is plates, and the prices of rolls and plates are also different. If you purchase rolls, it is calculated according to the actual weight, so the price is high, and the plate is calculated according to theory, so the price is low. , the reason is that there is a difference. For example, the thickness of 10mm may actually be 9.6mm, and there will be a price difference in the middle.
Stainless steel plates are divided into hot rolling and cold rolling according to the rolling process of the rolling mill (rolling mill is the machine name of the rolling plate). Hot rolling is usually marked as NO.1 and cold rolling is marked as 2B or BA (BA is better than 2B surface, To be bright, close to the mirror, the best is the mirror surface, the mirror surface is not in stock, and it needs to be processed), for example, 304 is often a purchase board, which means that the roll must be flattened into a plate by a machine, this machine is a flattening machine. The flattening machine can be opened into different lengths. If it is not a conventional length, it is called a fixed opening, which means that the size is fixed, because custo


Simple Calculation Method of Theoretical Weight of Stainless Steel Plate

Board weight = specific gravity × thickness (mm) × width (m) × length (m) (mm is the unit of millimeter, m is the unit of meter)
In the field of construction machinery, due to the emphasis on precision dimensions, millimeters are used in the world. 1000 mm = 1 meter, 1 mm = 100 wires.
The weight obtained according to this formula is kilograms (KG), which must be accurate to two decimal places. Because stainless steel is expensive and the transaction volume is large, the number after the decimal point is also very important, so the money should be accurate to two decimal places. bit.

Characteristics and uses of main stainless steel types

304: As a widely used steel, it has good corrosion resistance, heat resistance, low temperature strength and mechanical properties, good hot workability such as stamping and bending, no heat treatment hardening phenomenon, no magnetism, and the use temperature is minus 193 degrees to Positive 800 degrees.

Uses: tableware, kitchen utensils, water heaters, boilers, auto parts, medical equipment, food machinery, wine storage, pressure vessels (chemical machinery, chemical equipment).
As a low-carbon 304 steel, 304L has similar corrosion resistance to 304 under normal conditions, but after welding and stress relief, it has good intergranular corrosion resistance and can maintain good corrosion resistance without heat treatment. Corrosion resistance, generally used at 400 degrees,
Uses: petrochemical industry, building materials.
321 adds Ti element to 304 steel to prevent intergranular corrosion, suitable for positive 430 to 900 degrees, non-magnetic;
Uses: Automobile exhaust, heat exchangers, containers and other products that do not undergo heat treatment after welding, due to the addition of Ti element, are not suitable for making food processing equipment.
316 is low carbon, with MO added, so its corrosion resistance, atmospheric corrosion resistance and high temperature strength are particularly good. It can be used under harsh conditions, suitable for use below 900 degrees, and is non-magnetic.
Uses: equipment used in seawater, chemical, dye, paper, acetic acid, fertilizer and other production equipment, food industry and facilities in coastal areas, products with special requirements for resistance to intergranular corrosion.
309S/310S, these two kinds of materials, the content of nickel and chromium is relatively high, and the content of Si is increased at the same time, so that it has high temperature resistance and corrosion resistance. Among them, 309S can withstand repeated heating below 980 degrees, and the service temperature of 310S can reach 1200 degrees. Continuous use Temperature can be 1150 degrees, non-magnetic.
Uses: Suitable for key parts such as high-temperature electric furnace equipment, drying equipment, furnace materials, aviation, petrochemical, electric power, etc.
The 200 series is similar to the 304 in terms of low price and economy.
Uses: food processing utensils, kitchen equipment, food processing equipment, filters, milk tanks, durable consumer goods, washing machine accessories, water heaters, steel furniture, architectural decoration, decoration. In terms of fatigue resistance, 201 has a higher hardness, but its toughness is not as good as 304, and 304 has better fatigue resistance.



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