Stainless steel is a high-alloy steel that can resist natural corrosion. It has a beautiful surface and does not have to undergo surface treatment such as plating or painting.
Simple classification of stainless steel
Stainless steel can be roughly divided into 200, 300 and 400 series, among which the 300 series is the most commonly used, and the 200 and 400 series are alternatives to the 300 series to a certain extent. The 400 series can actually be called stainless iron, because it does not contain nickel, so it can be attracted by a magnet. However, the 200 and 300 series contain nickel, so they are not magnetic and cannot be absorbed by iron.
304 is the most common one in the 300 series, so generally the price trend of the entire stainless steel can be judged from the price change of 304. The 300 series can be simply divided into 304, 304L, 316, 316L, 321, 309S, 310S, etc. The classification is based on the content of various metal elements, the content of stainless steel is different, and the characteristics are different. For example, 304 and 304L, the difference between the two is the difference in carbon (C) content, with L means that the carbon content is low, so it is also called low carbon in the market, and the difference between 316 and 316L is the same.
Type classification of stainless steel
According to the different forms of stainless steel, stainless steel can be divided into five categories: coils, plates, profiles, steel pipes and parts, the most important of which are stainless steel coils and stainless steel plates. Profiles refer to materials of various shapes made of plates, such as angle steel, flat steel, I-beam, and channel steel. Steel pipe mainly refers to seamless steel pipe. The opposite of seamless steel pipe is welded pipe. The difference between the two is whether it is formed at one time. The components mainly refer to elbows and flanges and some other small things.
The coil and the sheet are actually the same, but the factory form is different. The coils are rolled one by one, and the plates are one by one. If the factory is made of sheet, this product is also called original sheet, which is generally thick, because it is very thick and cannot be rolled. Generally speaking, rolls of more than 16 mm cannot be formed. The price of stainless steel coils and plates are different. Stainless steel coils are calculated according to actual weight, while stainless steel plates are calculated according to theory. The price of stainless steel coil is higher than that of stainless steel plate. The reason is that there is a difference. For example, a 10mm thick stainless steel plate 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 different rolling processes. Hot rolling is usually marked as NO.1, and cold rolling is marked as 2B or BA (BA has a better and brighter surface than 2B. The best surface treatment method is mirror. Mirrors are generally not available in stock and need to be processed). The thickness of domestic cold-rolled sheets is generally below 3 mm, and the thickness of hot-rolled sheets is above 3 mm. Therefore, stainless steel plates with a thickness of 3 mm are both hot-rolled and cold-rolled. However, the thickness of imported cold-rolled plates can be less than 4 mm or even less than 6 mm. Hot-rolled plates with a thickness of 3 mm to 12 mm are called medium plates, and those with a thickness of 12 mm or more are called thick plates, and the thickness can be more than 120 mm, which is called hot-rolled medium and thick plates. Cold rolled is usually called cold rolled sheet.
Stainless steel calculation method
The weight calculation method of stainless steel plate:
Stainless steel plate weight = specific gravity × thickness (mm) × width (m) × length (m), the weight obtained according to this formula is kilogram (KG)
Calculation formula for other stainless steel products:
Stainless steel pipe: (outer diameter—wall thickness)×wall thickness×0.02491=Kg/m
Round steel: (diameter×diameter) 0.00623=Kg/M
Specific gravity of stainless steel (KG)
Different stainless steels have different specific gravity, also called stainless steel coefficient:
A, the specific gravity of the 400 series is 7.75
B, 304.321.304N.201.202.304L..301. The proportion is 7.93
C, the specific gravity of 310S.309S.316.316L is 7.98.
Different countries in the world have different names for stainless steel. The stainless steel of China and the United States is usually contacted in the market, that is, the national standard and the American standard. The 200, 300 and 400 series mentioned earlier are American standards. The comparison between the national standard and the American standard is as follows:
National Standard ============ American Standard
1cr17mn6ni5n========201
1cr18mn8ni5n========202
0cr18ni9============304
00cr19ni10==========304L
0cr18ni12mo2t=======316Ti
00cr17ni14mo2=======316L
0cr17ni12mo2========316
1cr18ni9ti==========321
0cr18ni10ti=========321
0cr23ni13===========309S
1cr20ni14===========309S
0cr25ni20===========310S
1cr25ni20===========310s
0cr13===============405
1cr13===============410
2cr13===============420
3cr13===============420
4cr3================430
The element content in the national standard generally refers to the intermediate value of the content, which is a theoretical value, which can be large or small.