Stainless steel knowledge summary

Update:30 Sep 2019
Summary:

1, stainless steel definition Stainless steel is a high […]

1, stainless steel definition
Stainless steel is a high-alloy steel that resists corrosion. It has an aesthetically pleasing surface and does not have to be surface treated with paint or paint. Therefore, many mechanical factories indicate that they are stainless steel, and often do not paint them, but black materials ( The so-called black material is the name of ordinary steel. It must be rust-proofed.
2, simple classification of stainless steel
Stainless steel can be divided into 200 series, 300 series and 400 series. Among them, 300 series is the most commonly used. 200 series and 400 series are the substitutes of 300 series in a certain range. Strictly speaking, 400 series is not called stainless steel. It is 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 there is no magnetism, and the iron can't be sucked.
304 is the most common variety in the 300 series, so the price change of 304 can generally determine the price trend of the whole stainless steel. The 200 series contains less nickel, the 400 series does not contain nickel, and the 300 series contains the most nickel, so the 300 series is most affected by the nickel price.
The 300 series can be divided into 304, 304L, 316, 316L, 321, 309S, 310S, etc. The basis for the distinction is the content of various metal elements, and the characteristics of stainless steel with different contents are different. The difference between 304 and 304L lies in The difference in carbon (C) content, the band L means that the carbon content is low, also called low carbon, and the difference between 316 and 316L is also the same.
3, stainless steel shape classification
Stainless steel can be divided into five categories: coils, plates, profiles, steel pipes and parts, the most important being rolls and plates. Profiles are a variety of different types of materials made of plates, including angle steel, flat steel, I-beam, channel steel. Steel pipes mainly refer to seamless steel pipes. Compared with seamless steel pipes, they are welded pipes. The difference is whether they are formed at one time. Parts mainly refer to elbows and flanges and other small things.
The coil and the plate are actually the same, the factory form is different, the coil is a roll, the plate is one piece, if the factory is the plate, also called the original plate, generally thick plate, because it is very thick If it is, it can't be rolled up. Generally, it can't be rolled up if it is more than 16 mm.
There are rolls, there are plates, and sometimes the price of plates, rolls and plates is not the same. If it is a purchase volume, it is calculated according to the actual weighing, so the price is high, the board is calculated according to the theory, and the price is low. The reason is that there is a difference, for example, the actual thickness of 10mm may be 9.6mm, there will be a spread in the middle.
The stainless steel plate is divided into hot rolling and cold rolling according to the rolling process of the rolling mill (the rolling mill is the machine name of the rolling plate), and the hot rolling is usually marked as NO.1 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, the mirror is not in stock, all need to be processed. For example, 304 is often a purchase board, which means that the roll must be flattened into a plate by the machine. This machine is a flattening machine. It can be opened to different lengths by opening the flattening machine. If it is not the regular length, it is called the fixed opening, which means the fixed opening size. Because the customer often proposes different length requirements according to the actual needs, the volume is important at this time. The board can't meet the requirements.