1. Stainless steel definition
Stainless steel is a high alloy steel that can resist corrosion. Has a beautiful surface, do not have to go through plating or paint surface treatment, so many machinery plants to show their own is stainless steel, often do not make any paint treatment, and the black material (the so-called black material is the name of the general iron and steel) must be rust treatment. Moreover, stainless steel is the most commonly used one, including stainless steel coil, stainless steel sheet plate, seamless stainless steel round tube for decoration, stainless steel square pipe for construction, stainless steel flat bar rod, stainless steel H beam, stainless structural steel I beam for building, etc.
2. Simple classification of stainless steel
Stainless steel can be roughly divided into 200 series, 300 series and 400 series of three categories.
Among them 300 series is the most commonly used, 200 series and 400 series is a certain range of 300 series of substitutes, and strictly speaking, 400 series is not called stainless steel, called stainless iron, because there is no nickel element, so the magnet can be attracted.
And 200 series and 300 series are nickel, so there is no magnetic, iron can not absorb.
304 is the most common variety in the 300 series, so generally from the price change of 304 can be judged the price trend of the whole stainless steel.
The 200 series contains less nickel, the 400 series contains no nickel, and the 300 series contains the most nickel, so the 300 series is the most affected by nickel price.
300 series can be simply divided into 304, 304L, 316, 316L, 321, 309S, 310S and so on, the basis of the distinction is different content of various metal elements, different content of stainless steel characteristics are not the same, is the carbon (C) content of different, with L is said to contain low carbon, also called low carbon, is the same.
3. Classification of stainless steel morphology
Stainless steel can be divided into stainless steel coil, stainless steel plate, stainless steel profile, stainless steel steel pipe and pipe fittings and parts of the five major categories, the most important is stainless steel coil and stainless steel sheet plate.
Stainless steel profile is the material of all sorts of different shapes that make it by board, have Angle bars, flat bars, I-beam, U channel steel.
Stainless steel pipe mainly refers to seamless steel pipe, and seamless steel pipe precision pipe is the opposite of welded pipe, the difference is whether a molding.
Stainless steel fittings parts mainly refers to elbow and flange and other small things.
Stainless steel coil and plate are actually the same, the factory form is not the same, coil is a roll of rolled stainless steel sheet plate, plate is a piece of plate cut from stainless steel coils, if the factory is plate, also called the original plate, is generally thick plate, because it is very thick, can not be rolled, generally 16 mm above can not be rolled.
Stainless steel coils and plate, usually customers purchase the plate, coli and plate price is not the same, if it is the purchase of volume, is calculated according to the actual weighing, so the price is high, plate is calculated in accordance with the theory, the price is low, the reason is that there is a difference, such as 10mm thick may actually be 9.6mm, there will be a price difference.
Stainless steel plate according to the mill (mill is the machine name of rolling plate) rolling process is different, into hot rolled stainless srteel sheet and cold rolled stainless steel sheet plat. Hot rolling is usually marked as NO.1 cold rolling is marked as 2B or BA(BA is better than 2B surface, bright, close to the mirror, the best is mirror, mirror is not in stock, all need to be processed), such as 304 many times is the purchase of plates, which means that the volume must be opened into the form of plate through the machine, this machine is the opening machine.
Through the opening machine can be opened into different lengths, if not the conventional length is called fixed, which means fixed size, because the customer according to the actual needs, often put forward different length requirements, at this time the volume is important, the conventional plate can not meet the requirements.
Domestic cold rolling is generally below 3 mm, hot rolling is generally above 3 mm, 3 mm thickness of both hot rolling, cold rolling, but the thickness of imported cold rolled plate can reach 4 mm or even 6 mm below.
Hot ROLLING 3 MM TO 12 mm PLATE CALLED plate, 12 MM above called thick plate, can be thick to 120 mm above, and hot rolling in thick plate, and cold rolling is cold rolling sheet.
Of course, for the MIM process, we actually use stainless steel powder.
4. Simple calculation method of theoretical weight of stainless steel plate
Board weight = specific gravity × thickness (mm)× width (m)× length (m)(mm is the unit of millimeters, m is the unit of meters)
In the field of construction machinery due to pay attention to precision size, the world uses millimeter as the unit 1000 mm =1 meter, 1 mm =100 wire.
According to this formula, the weight is kilograms (KG), to be accurate to two decimal places, because stainless steel is expensive, trading volume, the number after the decimal point is very important, so the money should also be accurate to two decimal places.
5 stainless steel specific weight proportion gravity (KG)
Different stainless steel has different specific gravity:
A, the specific gravity of the 400 series is 7.75
B, 304.321.304 n. 201.202.304 L.. 301. The specific gravity is 7.93
C, 310S.309S.316.316L specific gravity is 7.98.
6. Use steel cross reference table
All countries in the world have different names for stainless steel, the market is often in contact with China and the United States, called GB and American standard, said above 200 series 300 series 400 series is the American standard, the American standard because it is easy to understand, so usually called the American standard.
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 name generally refers to the intermediate value of the content, which is the theoretical value and can be large or small.
7. What is tolerance (this is for the stainless steel sheet plate)
This is an important term. Tolerance is the accepted allowable deviation in length or thickness. Because in the production process of plates, it's difficult for a variety of reasons. The actual thickness is often not up to the theoretical thickness, such as 6 mm plate, only 5.6 mm, this is the tolerance, in the domestic tolerance is often negative tolerance, of course, there are also positive tolerance, but very few. When buying and selling the board, it is usually calculated according to the theoretical thickness, which is also the reason why the theoretical price is lower than the weighing price. There are differences in the size of the tolerance, and the price is different. The price of large tolerance is cheaper. For example, for 6mm, if it is below 5.5, it is a large tolerance.
8. Characteristics and uses of the main stainless steel types
304: As a kind of widely used steel, has good corrosion resistance, heat resistance, low temperature strength and mechanical property, stamping, bending and other thermal processing, no heat treatment hardening phenomenon, no magnetic, the use of temperature -193 degrees to positive 800 degrees.
Uses: TABLEware, kitchenware, water heater, boiler, auto parts, medical equipment, food machinery, storage wine, pressure vessel (chemical machinery, chemical equipment).
304L: as a low carbon 304 steel, in the general state, corrosion resistance and 304 is almost the same, but after welding and stress elimination, it has good resistance to intergranular corrosion, in the case of no heat treatment, can also maintain good corrosion resistance, generally used at 400 degrees
Application: Petrochemical industry, building materials.
321: Add Ti element in 304 steel, to prevent mesocrystalline corrosion, suitable for positive 430 to 900 degrees below, non-magnetic;
Use: Automobile exhaust, heat exchangers, containers and other products without heat treatment after welding, due to the addition of Ti element, it is not suitable to make food processing equipment.
316:316 low carbon, add MO element, so its 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.
Applications: Equipment used in seawater, chemical, dye, paper, acetic acid, fertilizer and other production equipment, food industry and coastal area facilities, anti-intergranular corrosion products with special requirements.
309S/310S: These 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, of which 309S can withstand repeated heating below 980, 310S use temperature up to 1200 degrees, continuous use temperature can be 1150 degrees, no magnetic.
Application: Suitable for high temperature furnace equipment, drying equipment and other key parts, furnace materials, aviation, petrochemical, electric power, etc.
The 200:200 series is similar to the 304 at a cheap and economical price.
Applications: Food processing utensils, kitchen equipment, food processing equipment, filters, milk cans, consumer durables, washing machine accessories, water heaters, steel furniture, architectural decoration, decoration. Fatigue resistance, 201 hardness is greater, toughness is not as good as 304, or 304 fatigue resistance is better.
