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You have to know the basics of stainless steel
Source: | Author:kanglong | Publish time:2020-08-23 | 410 Views: | Share:
Stainless steel is a high alloy steel that resists corrosion. it has a beautiful surface, not to be plated or painted on the surface, so many mechanical plants to indicate that it is stainless steel, often do not do any paint treatment, and the black wood ( so - called black wood is the name of general steel ) is must be antirust treatment.
Stainless steel definition
Stainless steel is a high alloy steel that resists corrosion. it has a beautiful surface, not to be plated or painted on the surface, so many mechanical plants to indicate that it is stainless steel, often do not do any paint treatment, and the black wood ( so - called black wood is the name of general steel ) is must be antirust treatment. 

Simple classification of stainless steel
Stainless steel can be divided into 200 series, 300 series and 400 series, of which 300 series are the most commonly used, 200 series and 400 series of courses are 300 series of substitutes, and strictly speaking, 400 series is not stainless steel, called stainless steel iron, because there are no nickel elements, so magnets can be attracted. The 200 series and 300 series are nickel, so there is no magnetic, the absorption of iron does not live. 

304 is the most common variety of the 300 series, so generally the price changes from 304 can determine the price trend of the whole stainless steel. The 200 series contains less nickel, 400 series does not contain nickel, 300 series contain the most nickel, so the 300 series is the most affected by nickel price. 

The 300 series can be divided into 304, 304 l, 316, 316l, 321, 309 s, 310 s, etc., the difference is based on the content of various metal elements, the characteristics of stainless steel with different content are also different, the difference between 304 and 304 lies in the difference of carbon ( c ) content, with l the difference is also the difference between the low carbon, 316 and 316l.

Morphological classification of stainless steel
Stainless steel can be divided into coil, plate, profile, steel pipe and parts of five categories, the most important is the volume and plate. Profile is a variety of materials made from the plate, angle steel, flat steel, I - beam, channel steel. Steel pipe is mainly refers to seamless steel pipe, and seamless steel pipe is relative to the welded pipe, the difference is whether it is formed once. The parts are mainly elbow and flange and other small things.

Coil and plate are actually the same, the factory is not the same, the coil is a roll, sheet is a sheet, plate is a sheet, if the factory is a plate, also called original plate, generally thick plate, because very thick, is unable to roll, generally more than 16 mm can not lap.

There is a volume, there are plates, many times are board, the price of the volume and board is different, if the purchase volume, 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 a lower difference, such as the actual 10 mm thick may be 9.6 mm, there will be a price difference in the middle.

The stainless steel plate is divided into hot and cold rolling according to the different rolling process of the mill ( mill is the machine name of the rolling plate ), the hot rolling is usually marked as no 1 cold rolling standard 2b or ba ( the surface is good, bright, close to the mirror, the best is mirror, the mirror is not in stock, all need processing ), such as 304 many times is the purchase board, that means the volume must be through the machine Kaiping form, this kind of machine is Kaiping machine. Kaiping can open into different lengths, if not the regular length is called, the meaning is to open size, because the customer according to the actual needs, often will put forward different length requirements, 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 more than 3 mm, 3 mm thickness of both hot and cold, but imported cold rolled sheet thickness can reach up to 4 mm or even 6 mm below. Hot rolled 3 mm to 12 mm plate is called medium plate, 12 mm or more is called thick plate, can be thicker than 120 mm thick, and said hot rolled plate, and cold rolling is cold rolled sheet.

Simple calculation method of theoretical weight of stainless steel plate
Plate weight = weight × thickness ( mm ) × width ( m ) × length ( m ) ( mm is the unit of mm, m is the unit of meter )

In the field of engineering machinery, due to precision dimensions, the world is in millimeters in units of 1000 mm = 1 m, 1 mm = 100 silk. 

According to this formula the weight is kilogram ( kg ), to be accurate to two decimal places, because the price of stainless steel, the volume of transactions, the number after the decimal point is very important, so the money should be accurate to two decimal places. 

Weight of stainless steel ( kg )

Different kinds of stainless steel have different proportions:
A, the proportion of 400 series is 7.75
B, 304.321.304N.201.202.304L.301 specific gravity is 7.93
C, 310 s 309 s 316.316 l specific gravity is 7.98.


Using the steel grade comparison table
The world's name for stainless steel is different, the market is often in contact with China and the United States, called the national standard and American standard, the 200 series of 300 series is American standard, American standard is generally known as 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 is generally refers to the content of the intermediate value, for the theoretical value, can be small.

What is the tolerance
This is a very important noun, tolerance is generally accepted as allowable length or thickness deviation because in the production process of the plate, for various reasons is difficult. The actual thickness is often less than the thickness of the theory, such as 6 mm plate, only 5.6 mm, this is the tolerance, in the domestic tolerance is often the negative tolerance, of course, there are also positive tolerance, but very few. In the trading plate, usually calculated according to the theoretical thickness, this is why the theoretical price is lower than the weighing price, the tolerance and the size of the point, the price is not the same, the price of the large tolerance is cheap. for example, if it is 5.5, the Grand duke is inferior. 

Characteristics and applications of main types of stainless steel
304: as a widely used steel, it has good corrosion resistance, heat resistance, low temperature strength and mechanical properties, punching, bending and other hot processing, no heat treatment hardening phenomenon, no magnetic, using temperature of minus 193 degrees to 800 degrees. 
Uses: tableware, kitchenware, water heater, boiler, auto parts, medical equipment, food machinery, storage vessels, pressure vessel ( chemical machinery, chemical equipment ). 

304 l as a low carbon 304 steel, in a general state, the corrosion resistance is similar to 304, but after welding and elimination of stress, it is resistant to intergranular corrosion, in the absence of heat treatment, it can also maintain good corrosion resistance, generally under 400 degrees of use,
Uses: petrochemical industry, building materials.


321'S Ti element is added to 304 steel to prevent intergranular corrosion, which is suitable for the less than 430 to 900 degrees and is not magnetic; 
Purpose: automobile exhaust, heat exchanger, container and other products after welding without heat treatment, due to the addition of ti elements, it is not suitable to make food processing equipment. 

316 low - carbon, adding mo elements, so his corrosion resistance and atmospheric corrosion and high temperature strength properties are particularly good, can be used under harsh conditions, suitable for use below 900 degrees, no magnetic. 
Uses: equipment used in seawater, chemical, dyestuff, paper making, acetic acid, fertilizer and other production equipment, food industry and coastal area facilities, anti - crystal corrosion products with special requirements. 

These two kinds of materials, the content of nickel and chromium is relatively high, while adding Si content, make it have high temperature resistance and corrosion resistance, of which 309 can withstand the following repeated heating, 310 uses the temperature to 1200 degrees, the continuous use temperature can be 1150 degrees, no magnetic. 
Application: suitable for high temperature electric furnace equipment, drying equipment and other key parts, furnace materials, aviation, petrochemical, power and so on. 

The 200 series is similar to 304, cheap economy. 
Uses: food processing utensils, kitchen equipment, food processing equipment, filters, milk cans, consumer durables, washing machine accessories, water heaters, steel furniture, architectural decoration, decoration. In the aspect of fatigue resistance, 201 hardness is greater, toughness is less than 304, or 304 is better fatigue resistance.