1. Simple classification of stainless steel
Stainless steel can be roughly divided into three categories: 200 series, 300 series and 400 series, among which 300 series is the most commonly used, 200 series and 400 series are substitutes for 300 series to a certain extent, and 400 series is not called stainless steel strictly speaking called stainless iron, because it does not contain nickel, it can be attracted by a magnet. The 200 series and 300 series have nickel, so they are not 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 does not contain nickel, and the 300 series contains the most nickel. Therefore, the 300 series is most affected by the nickel price.
The 300 series can be simply divided into 304, 304L, 316, 316L, 321, 309S, 310S, etc. The distinction is based on the content of various metal elements, and the characteristics of stainless steel with different content are different. The difference between 304 and 304L is The carbon (C) content is different. The one with L means low carbon content, which is also called low carbon. The difference between 316 and 316L is the same.
2. The shape 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.
Pipe mainly refers to seamless steel pipe, and the opposite of seamless steel pipe is welded pipe. The difference is whether it is formed at one time. Parts mainly refer to elbows and flanges and other small things.
The coil and the plate are actually the same, and the factory form is different. The coil is rolled one by one, and the plate is one by one. If the plate is shipped from the factory, it is also called the original plate. It is generally a thick plate because it is very thick. If it is, it cannot be rolled, generally it cannot be rolled if it is more than 16 mm.
Stainless steel plate is divided into hot rolling and cold rolling according to the different rolling process of the rolling mill (the rolling mill is the machine name of the rolling plate). To be bright, close to the mirror, the best is the mirror surface. The mirror surface is not in stock and needs to be processed). For example, 304 is often a purchased board, which means that the roll must be flattened by a machine. This kind of machine is a flattening machine.
3. Main types of stainless steel and its characteristics and uses
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, non-magnetic, and the use temperature is minus 193 degrees It is 800 degrees. Uses: tableware, kitchenware, 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 the same corrosion resistance as 304 under normal conditions, but after welding and stress relief, it has good intergranular corrosion resistance and can maintain good intergranular corrosion 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. It is suitable for 430 to 900 degrees below, non-magnetic; use: automobile exhaust, heat exchanger, container and other products that do not undergo heat treatment after welding, due to the addition of Ti Element is not suitable for making food processing equipment.
316 has low carbon and added MO elements, so its corrosion resistance, atmospheric corrosion resistance and high temperature strength performance are particularly good. It can be used under harsh conditions and is suitable for use below 900 degrees. It is non-magnetic. Uses: equipment used in seawater, chemical, dye, paper, acetic acid, fertilizer and other production equipment, food industry and coastal facilities, products with special requirements for resisting intercrystalline corrosion.
The two materials of 309S/310S have relatively high content of nickel and chromium. At the same time, the content of Si is increased to make it have high temperature resistance and corrosion resistance. Among them, 309S can withstand repeated heating below 980, and 310S can be used at a temperature of 1200 degrees, continuous use The 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 304, which is cheap and economical. Uses: food processing utensils, kitchen equipment, food processing equipment, filters, milk tanks, durable consumer goods, washing machine parts, water heaters, steel furniture, building decoration, decoration. In terms of fatigue resistance, the hardness of 201 is greater, but the toughness is not as good as that of 304, but the fatigue resistance of 304 is better.
