Stainless steel knowledge summary, see this one is enough! - Shandong Jiugang Tisco Steel Co., Ltd.

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Stainless steel knowledge summary, see this one is enough!

  1、Definition of stainless steel

Stainless steel is a high alloy steel that can resist corrosion. With a beautiful surface, do not have to go through color plating or paint and other surface treatment, so many mechanical plants to show that theirs is stainless steel, often without any paint treatment, while the black material (so-called black material is the name of the general steel) is necessary for the anti-rust treatment.

  2、Simple classification of stainless steel

Stainless steel can be roughly divided into 200 series, 300 series and 400 series three categories, of which 300 series is commonly used, 200 series and 400 series is a certain course of 300 series of alternatives, and strictly speaking 400 series is not called stainless steel, called stainless steel, because it does not contain nickel elements, so the magnet can be attracted. And 200 series and 300 series are nickel, so there is no magnetic, suction iron can not be absorbed.

304 is a common species in the 300 series, so generally from the price change of 304 can determine the price trend of the entire stainless steel. 200 series contains less nickel, 400 series does not contain nickel, 300 series contains more nickel, so the nickel price is affected by the 300 series.

300 series can be briefly divided into 304, 304L, 316, 316L, 321, 309S, 310S and so on, the basis of distinction is the content of various metal elements are different, the content of different stainless steel characteristics are not the same, 304 and 304L difference is the difference in carbon (C) content, with L is said to contain low carbon, also known as low carbon, 316 and 316L difference is also The same.

  3、the form of stainless steel classification

Stainless steel can be divided into five categories: coils, plates, profiles, steel pipes and parts, the important volume and plate. Profiles are a variety of different shaped materials made of plate, there are angles, 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 refer to elbows and flanges and other small things.

Coil and plate is actually the same, the factory form is not the same, coil is a roll of a roll, plate is a sheet, if the factory is a plate, also called the original plate, generally thick plate, because very thick, it is impossible to become a volume, generally more than 16 mm can not be a volume.

There are volumes, there are plates, many times the plate, volume and plate prices are not the same, if the purchase of volumes, is calculated according to the actual weighing, so the price is high, the plate is calculated according to the theory, the price is low, the reason is that there is under the difference, such as 10mm thick may actually be 9.6mm, which will have a price difference in the middle.

Stainless steel plate according to the rolling mill (mill is the name of the machine that rolls the plate) rolling process is different, divided into hot-rolled and cold-rolled, hot-rolled is usually marked as NO.1 cold-rolled marked as 2B or BA (BA than 2B surface is good, to bright, close to the mirror, good is the mirror, mirror surface is not in stock, are required to process), such as 304 many times is the purchase of the plate, that means the volume must be flattened by machine into the form of the plate. This machine is the flattening machine. Through the flattening machine flattening can be opened into different lengths, if not the conventional length is called fixed open, meaning fixed open size, because customers according to the actual needs, often put forward different length requirements, this time the volume becomes important, the conventional plate will not meet the requirements.

  Domestic cold-rolled generally below 3 mm, hot-rolled generally above 3 mm, 3 mm thickness of both hot-rolled and cold-rolled, but imported cold-rolled plate thickness can reach below 4 mm or even below 6 mm. Hot-rolled 3 mm to 12 mm plate called medium plate, 12 mm or more called thick plate, can be thicker than 120 mm, and called hot-rolled plate, and cold-rolled is cold-rolled thin plate.
   4 、 What is called tolerance

This is a very important term, tolerance is recognized as the allowable length or thickness deviation. Because in the production process of the plate, for various reasons it is difficult. Out of the actual thickness is often not up to the theoretical thickness, such as 6 mm plate, only 5.6 mm, which is the tolerance, in the domestic tolerance is often negative tolerance, of course, there are positive tolerances, but rarely. In the sale of the board, usually according to the theoretical thickness to calculate, which is why the theoretical price is lower than the price of weighing, tolerance and the size of the difference, the price is not the same, the price of large tolerance is cheaper. For example, 6 mm, if it is 5.5 or less is a large tolerance.

   5、The characteristics and uses of the main stainless steel types

304: As a widely used steel, 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 the temperature of minus 193 degrees to positive 800 degrees.

Uses: tableware, kitchenware, water heaters, boilers, auto parts, medical equipment, food machinery, storage wine ware, pressure vessels (chemical machinery, chemical equipment).

304L: As low-carbon 304 steel, in general state, corrosion resistance is similar to 304, but after welding and stress relief, it resists intergranular corrosion well and maintains good corrosion resistance without heat treatment, generally used at 400 degrees.

Uses: petrochemical industry, building materials.

321 in 304 steel added Ti elements to prevent intergranular corrosion, suitable for positive 430 to 900 degrees below, non-magnetic;

Uses: automotive exhaust, heat exchangers, containers and other products that are not heat-treated after welding, due to the addition of Ti elements, it is not suitable for making food processing equipment.

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 in 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 area facilities, products with special requirements against intergranular corrosion.

309S/310S two materials, nickel and chromium content is relatively high, while increasing the content of Si, so that it has high temperature resistance and corrosion resistance, which 309S can withstand repeated heating below 980, 310S use temperature up to 1200 degrees, continuous use temperature can be 1150 degrees, non-magnetic.

Uses: Applicable high-temperature electric furnace equipment, drying equipment and other key parts, furnace materials, aviation, petrochemical, electric power, etc.

200 series similar to 304 cheap price economy.

Uses: food processing utensils, kitchen equipment, food processing equipment, filters, milk cans, durable consumer goods, washing machine parts, water heaters, steel furniture, architectural decoration, decoration. Fatigue resistance, 201 hardness is greater, toughness is not as 304, or 304 fatigue resistance is better.



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