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WHAT IS STAINLESS STEEL?

2021-03-12 10:58:17

Stainless steel (Stainless Steel) is the abbreviation of stainless and acid-resistant steel.


It is called stainless steel that is resistant to weak corrosive media such as air, steam, and water, or is stainless steel; and chemically resistant to chemical corrosion media (acid, alkali, salt, etc.) Corrosion steel is called acid-resistant steel.


Due to the difference in the chemical composition of the two, their corrosion resistance is different. Ordinary stainless steel is generally not resistant to chemical media corrosion, while acid-resistant steel is generally non-corrosive. The term "stainless steel" not only refers to a single type of stainless steel, but also refers to more than one hundred industrial stainless steels. Each stainless steel developed has good performance in its specific application field. The key to success is to understand the purpose first, and then determine the correct steel grade. There are usually only six steel grades related to the application of building construction.

They all contain 17-22% chromium, and better steel grades also contain nickel. The addition of molybdenum can further improve the atmospheric corrosion, especially the corrosion resistance of the chloride-containing atmosphere.


Generally speaking, the hardness of stainless steel is higher than that of aluminum alloy, and the cost of stainless steel is higher than that of aluminum alloy.

According to the composition, it can be divided into Cr series (400 series), Cr-Ni series (300 series), Cr-Mn-Ni (200 series), heat-resistant chromium alloy steel (500 series) and precipitation hardening series (600 series).


200 series: chromium-manganese-nickel

201, 202, etc.: Substituting manganese for nickel, which has poor corrosion resistance and is widely used as a cheap substitute for the 300 series in China


300 series: chromium-nickel austenitic stainless steel

301: Good ductility, used for molded products. It can also be hardened by mechanical processing. Good weldability. Abrasion resistance and fatigue strength are better than 304 stainless steel.

302: The corrosion resistance is the same as that of 304, and the strength is better due to the relatively high carbon content.

303: By adding a small amount of sulfur and phosphorus, it is easier to cut than 304.

304: Universal model; that is, 18/8 stainless steel. Products such as: corrosion-resistant containers, tableware, furniture, railings, medical equipment. The standard composition is 18% chromium plus 8% nickel. It is a non-magnetic stainless steel whose metallographic structure cannot be changed by heat treatment. The GB grade is 06Cr19Ni10.

304 L: Same characteristics as 304, but low carbon so it is more resistant to corrosion and easy to heat treatment, but has poor mechanical properties. Suitable for welding and products that are not easy to heat treatment.


304 N: Same characteristics as 304. It is a nitrogen-containing stainless steel. Nitrogen is added to increase the strength of the steel.

309: It has better temperature resistance than 304, with a temperature resistance of up to 980°C.

309 S: It has a large amount of chromium and nickel, so it has good heat resistance and oxidation resistance. Products such as heat exchangers, boiler components, and jet engines.

310: Excellent high temperature oxidation resistance, the highest operating temperature is 1200℃.

316: After 304, the second most widely used steel grade. It is mainly used in the food industry, watch jewelry, pharmaceutical industry and surgical equipment. The addition of molybdenum makes it a special corrosion-resistant structure. Because it has better resistance to chloride corrosion than 304, it is also used as "ship steel". SS316 is usually used in nuclear fuel recovery devices. 18/10 grade stainless steel usually also meets this application level.

316 L: Low carbon, more corrosion resistant, easy to heat treatment, products such as: chemical processing equipment, nuclear power generators, refrigerant storage tanks.

321: Except that the addition of titanium reduces the risk of corrosion of the material welds, other properties are similar to 304.

347: Add stabilizing element niobium, suitable for welding aviation appliance parts and chemical equipment.


400 series: ferritic and martensitic stainless steel, without manganese, can replace 304 stainless steel to a certain extent

408: Good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni.

409: The cheapest model (British and American), usually used as a car exhaust pipe, is a ferritic stainless steel (chrome steel).

410: Martensite (high-strength chromium steel), good wear resistance, poor corrosion resistance.

416: The addition of sulfur improves the processing performance of the material.

420: "Cutting tool grade" martensitic steel, similar to the earliest stainless steel such as Brinell high chromium steel. It is also used for surgical knives, which can be very bright.

430: Ferritic stainless steel, for decoration, such as car accessories. Good formability, but poor temperature resistance and corrosion resistance.

440: High-strength cutting tool steel with slightly higher carbon content. After proper heat treatment, higher yield strength can be obtained. The hardness can reach 58HRC, which is among the hardest stainless steels. The most common application example is the "razor blade". There are three commonly used models: 440A, 440B, 440C, and 440F (easy processing type).

500 series: heat-resistant chromium alloy steel.

600 series: Martensitic precipitation hardening stainless steel.


Stainless steel mesh

Stainless steel mesh is also known as stainless steel filter mesh because it is mainly used for filtering products.

Material: SUS201, 202, 302, 304, 316, 304L, 316L, 321 stainless steel wire, etc.

Weaving: plain weave, twill weave, dense weave.

Mesh number: The specification of stainless steel wire mesh is 1 mesh-635 mesh. The mat-shaped weaving can reach 2800 meshes.

Uses: stainless steel mesh and other metal wire woven meshes are mainly used for screening and filtering under acid and alkali environmental conditions, mud meshes in the petroleum industry, screen filters in the chemical and chemical fiber industry, pickling meshes in the electroplating industry, gas and liquid filtration and others For media separation.


Mesh belt

Classified by name: stainless steel mesh belt, conveyor belt, metal conveyor belt, stainless steel conveyor belt, metal mesh belt, metal conveyor belt, stainless steel transmission belt, metal transmission mesh belt, etc.

Classified by purpose: Widely used in annealing furnace mesh belts and baking furnace mesh belts in the glass products industry. Food processing industry, dehydrated vegetables, quick-frozen food single-freezer pre-processing mesh belt, chain mesh. Powder metallurgy, metal heat treatment, quenching, sintering, brazing, roasting, bright, blackening, bearing, carburizing high-temperature furnace mesh belt, baffle mesh belt, coating drying line conveyor mesh belt, foam nickel reduction production line mesh belt , Washing machine, hoist, dryer, dryer, curing oven mesh belt. Chain nets and mesh belts for each conveying process.

Classified by material: 1cr13 mesh belt, 201 mesh belt, 304 mesh belt, 316 mesh belt, etc.

Classified by shape: herringbone mesh belt, B-shaped mesh belt, diamond mesh belt, horseshoe mesh belt, chain conveyor belt, glasses-shaped mesh belt, chain plate mesh belt, spherical mesh belt

Expansion of stainless steel products: stainless steel mesh belts, mesh belts, conveyor mesh belts, metal mesh belts, high temperature mesh belts, Great Wall mesh belts, type B mesh belts, stainless steel accessories. All products in the expansion are made of stainless steel steel wires and stainless steel plates.


magnetic

The austenitic type is non-magnetic or weakly magnetic, and martensite and ferrite are magnetic. After austenite is cold-worked, its structure will also be transformed into martensite, and the magnetic properties will become larger. Therefore, the method of distinguishing the quality and the authenticity of stainless steel through magnet adsorption is one-sided and wrong.

Stainless steel surface processing grade

Original surface: NO.1 The surface subjected to heat treatment and pickling treatment after hot rolling. Generally used for cold-rolled materials, industrial tanks, chemical industrial equipment, etc., the thickness is thicker from 2.0MM to 8.0MM.


Blunt surface: NO.2D cold-rolled after heat treatment and pickling, its material is soft, the surface is silver-white luster, used for deep drawing processing, such as automotive components, water pipes, etc.

Matte surface: NO.2B after cold rolling, heat treatment, pickling, and then finishing rolling to make the surface moderately bright. Because the surface is smooth and easy to re-grind, it makes the surface brighter and has a wide range of uses, such as tableware, building materials, etc. After adopting the surface treatment to improve the mechanical properties, it can meet almost all purposes.

Coarse sand NO.3 is a product grinded with No. 100-120 grinding belt. It has better gloss and discontinuous rough lines. Used in building interior and exterior decoration materials, electrical products and kitchen equipment, etc.

Fine sand: NO.4 is a product grinded with grit size 150-180 grinding belt. It has better gloss, discontinuous rough lines and finer stripes than NO.3. Used in baths, decoration materials inside and outside buildings, electrical products, kitchen equipment and food equipment, etc.


#320 The product is polished with 320 abrasive belt. It has better gloss, discontinuous rough lines, and finer stripes than NO.4. Used in baths, interior and exterior decoration materials of buildings, electrical products, kitchen equipment and food equipment, etc.

Hairline surface HAIRLINE: HLNO.4 is a product with a grinding pattern generated by continuous grinding with a polishing belt of appropriate granularity (subdivision 150-320). Mainly used for building decoration, elevators, building doors, panels, etc.

Bright surface: BA is a product obtained by bright annealing after cold rolling and smoothing. The surface gloss is excellent and has a high reflectivity. Like a mirror surface. Used in home appliances, mirrors, kitchen equipment, decoration materials, etc.


Application field

In the field of construction applications, the surface processing of stainless steel is important for many reasons. The corrosive environment requires a smooth surface because the surface is smooth and not easy to accumulate. The deposit of dirt will cause stainless steel to rust and even cause corrosion.

In a spacious hall, stainless steel is the most commonly used material for elevator decorative panels. Although the fingerprints on the surface can be wiped off, it affects the appearance. Therefore, it is best to choose a suitable surface to prevent fingerprints from being left.

Sanitary conditions are very important to many industries, such as food processing, catering, brewing, and chemicals. In these applications, the surface must be easy to clean every day, and chemical cleaning agents are often used.


Stainless steel is the best material in this regard. In public places, the surface of stainless steel is often scribbled. However, an important feature of it is that they can be washed away. This is a significant feature of stainless steel over aluminum. It is easy to leave marks on the surface of aluminum, which is often difficult to remove. When cleaning the surface of stainless steel, you should follow the lines of stainless steel, because some of the lines processed on the surface are unidirectional.

Stainless steel is most suitable for hospitals or other areas where sanitary conditions are critical, such as food processing, catering, brewing and chemical engineering. This is not only because it is easy to clean every day, and sometimes chemical cleaning agents are used, but also because it is not easy to breed bacteria . Tests show that the performance in this respect is the same as that of glass and ceramics.