Some summary knowledge of Stainless steel
The definition of stainless steel
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 any black material. The so-called black material is the name of ordinary steel. It must be rust-proofed.
Summary classify 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, it can be attracted by a magnet. The 200 series and the 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 entire 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 the 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.
Characteristics and uses of the 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, no magnetism, and the temperature is minus 193 degrees. It is 800 degrees.
Uses: tableware, kitchen utensils, water heaters, boilers, auto parts, medical equipment, food machinery, storage wine, pressure vessels (chemical machinery, chemical equipment).
304L: As a low-carbon 304 steel, under normal conditions, the corrosion resistance is similar to that of 304, but after welding and after stress relief, it is resistant to intergranular corrosion and can be maintained well without heat treatment. Corrosion resistance is generally used at 400 degrees.
Uses: petrochemical industry, building materials.
321 added Ti element in 304 steel to prevent intergranular corrosion, suitable for positive 430 to 900 degrees, non-magnetic;
Uses: Automotive exhaust, heat exchangers, containers, etc., which are not heat treated after welding, are not suitable for making food processing equipment due to the addition of Ti.
316 low carbon, adding MO element, 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 seawater, chemical, dye, paper, acetic acid, fertilizer and other production equipment, food industry and coastal facilities, products with special requirements against intergranular corrosion.
309S/310S two materials, nickel and chromium content is relatively high, while increasing the Si content, making it resistant to high temperature and corrosion, which 309S can withstand repeated heating below 980, 310S use temperature reached 1200 degrees, continuous use The temperature can be 1150 degrees and is non-magnetic.
Uses: Suitable for high temperature electric furnace equipment, drying equipment and other key parts, furnace materials, aviation, petrochemical, electricity and so on.
The 200 series is similar to the 304 cheap economy.
Uses: food processing utensils, kitchen equipment, food processing equipment, filters, milk cans, consumer durables, washing machine parts, water heaters, steel furniture, architectural decoration, decoration. In terms of fatigue resistance, 201 has a high hardness, and the toughness is not as good as 304, or the fatigue resistance of 304 is better.