How much do you know about stainless steel?

【Summary Description】 Stainless steel is a high-alloy steel that resists corrosion. Has a beautiful surface, do not have to go through the plating color or paint and other surface treatment, so many machinery factory to show their own is stainless steel, often do not do any paint treatment, and the black material (the so-called black material is the general steel name) must be rust-proof treatment. Simple classification of stainless steel Stainless steel can be roughly divided into three categories: 200 series, 300 series and 400 series, of which 300 series is the most commonly used. 200 series and 400 series are substitutes for 300 series in a certain way. Strictly speaking, 400 series is not called stainless steel, but stainless iron. Because it does not contain nickel, it can be attracted by magnets. However, the 200 series and the 300 series are made of nickel, so they are not magnetic and cannot absorb iron. 304 is the most common variety in the 300 series, so the price trend of the whole stainless steel can be judged from the price change of the 304. 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. 300 series can be simply divided into 304, 304L, 316, 316L, 321, 309S, 310S, etc. The distinction is based on the different contents of various metal elements and the different characteristics of stainless steel with different contents. The difference between 304 and 304L lies in the different carbon (C) content. The one with L means low carbon, 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 coil, plate, profile, steel pipe and parts five categories, the most important is the coil and plate. Profile is a variety of different types of materials made of plate, angle steel, flat steel, I-beam, channel steel. Steel pipe mainly refers to seamless steel pipe, and seamless steel pipe is the opposite of welded pipe, the difference is whether a forming. Parts mainly refers to elbows and flanges and other small things. Coils and plates are actually the same, but the factory forms are different. Coils are rolled one by one, and plates are rolled one by one. If they are manufactured as plates, they are also called original plates, which are usually thick plates, because if they are very thick, they cannot be rolled, and generally they cannot be rolled over 16mm. If there are rolls and plates, the prices of rolls and plates are often different. If the rolls are purchased, they are calculated according to the actual weighing. Therefore, if the prices are high and the plates are calculated according to the theory, the prices are low. The reason is that there is a difference. For example, the actual price of 10mm thick may 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 different rolling processes of the rolling mill (the rolling mill is the machine name of the rolling plate). Hot rolling is usually marked as NO. 1 Cold rolling is marked as 2B or BA(BA has a better surface than 2B, is brighter, and is close to the mirror. The best one is the mirror surface. The mirror surface has no in stock and needs to be processed). For example, 304 often purchases plates, which means that the rolls must be leveled into plates by a machine. This machine is a leveler. Kaiping can be opened into different lengths by Kaiping machine. If it is not regular length, it is called fixed opening, which means fixed opening size, because customers often put forward different length requirements according to actual needs. At this time, the roll is important, and the regular board cannot meet the requirements. Domestic cold rolling is generally below 3mm, hot rolling is generally above 3mm, and the thickness of 3mm is both hot rolling and cold rolling, but the thickness of imported cold rolled plate can reach below 4mm or even below 6mm. Hot-rolled plates of 3mm to 12mm are called medium plates, and plates above 12mm are called thick plates, which can be as thick as 120mm or more. They are also called hot-rolled medium plates, while cold-rolled plates are cold-rolled thin plates. Characteristics and uses of the main types of stainless steel 304: As a widely used steel, it has good corrosion resistance, heat resistance, low temperature strength and mechanical properties, stamping, bending and other hot workability, no heat treatment hardening phenomenon, non-magnetic, the use of temperature minus 193 degrees to 800 degrees. Uses: tableware, kitchenware, water heaters, boilers, auto parts, medical equipment, food machinery, storage wine, pressure vessels (chemical machinery, chemical equipment). 304L as a low-carbon 304 steel, in the general state, the corrosion resistance and 304 almost, but after welding and after the elimination of stress, it anti-intergranular corrosion is good, in the absence of heat treatment, can also maintain good corrosion resistance, generally used at 400 degrees, Uses: petrochemical industry, building materials. 321 adding Ti element in 304 steel to prevent intergranular corrosion, suitable for positive 430 to below 900 degrees, non-magnetic; Uses: Products that are not heat-treated after welding, such as automobile exhaust, heat exchangers, containers, etc., are not suitable for food processing equipment due to the addition of Ti. 316 low carbon, add MO elements, so his corrosion resistance and atmospheric corrosion resistance and high temperature strength performance is particularly good, can be used under harsh conditions, suitable for use below 900 degrees, non-magnetic. Uses: equipment used in sea water, chemical, dye, paper, acetic acid, fertilizer and other production equipment, food industry and coastal facilities, products with special requirements against intercrystalline corrosion. 309S/310S these two materials, the content of nickel and chromium is relatively high, while increasing the content of Si, so that it has high temperature resistance and corrosion resistance, of which 309S can withstand repeated heating below 980, 310S use temperature reaches 1200 degrees, continuous use temperature can be 1150 degrees, non-magnetic. Uses: suitable for high temperature electric furnace equipment, drying equipment and other key parts, furnace materials, aviation, petrochemical, electric power, etc. 200 series is similar to the 304 cheap economy. Uses: food processing utensils, kitchen equipment, food processing equipment, filters, milk cans, durable consumer goods, washing machine accessories, water heaters, steel furniture, building decoration, decoration. In terms of fatigue resistance, 201 the hardness is larger, the toughness is not as good as the 304, or the fatigue resistance of the 304 is better.

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