Stainless steel knowledge 30 1 stainless steel

Stainless steel refers to steel resistant to weak corrosive media such as air, steam and water and chemical corrosive media such as acid, alkali and salt, also known as stainless acid-resistant steel. In practical application, steel resistant to weak corrosive medium is usually called stainless steel, while steel resistant to chemical medium is called acid-resistant steel. Because of the different chemical composition, the former is not necessarily resistant to the corrosion of chemical media, while the latter is generally stainless. The corrosion resistance of stainless steel depends on the alloying elements contained in the steel. Stainless steel is often divided into martensitic steel, ferritic steel and austenitic steel according to its microstructure. In addition, it can also be divided into chromium stainless steel, chromium nickel stainless steel and chromium manganese nitrogen stainless steel.

1, ferritic stainless steel: containing 12% ~ 30% chromium. Its corrosion resistance, toughness and weldability increase with the increase of chromium content, and its chloride stress corrosion resistance is better than other kinds of stainless steel.

There are Crl7, Cr 17Mo2Ti, Cr25, Cr25Mo3Ti, Cr28, etc. Ferritic stainless steel has good corrosion resistance and oxidation resistance because of its high chromium content, but its mechanical properties and technological properties are poor, so it is mostly used in acid-resistant structures with less stress and as oxidation-resistant steel. This kind of steel can resist the corrosion of atmosphere, nitric acid and brine solution, and has the characteristics of good oxidation resistance at high temperature and small thermal expansion coefficient. It can be used in nitric acid and food factory equipment, and can also be used to manufacture parts that work at high temperature, such as gas turbine parts.

2. Austenitic stainless steel: containing more than 18% of chromium, about 8% of nickel and a small amount of elements such as molybdenum, titanium and nitrogen. Good comprehensive performance, corrosion resistance to various media. Commonly used brands of austenitic stainless steel are 1Cr 18Ni9, 0Cr 19Ni9, etc. lavatory

3. Austenite-ferrite duplex stainless steel: It has the advantages of both austenitic and ferritic stainless steel and is superplastic.

About half austenite and half ferrite stainless steel. In the case of low C content, Cr content is 18%~28%, and Ni content is 3%~ 10%. Some steels also contain alloying elements, such as molybdenum, copper, silicon, niobium, titanium and nitrogen. This steel has the characteristics of both austenitic and ferritic stainless steel. Compared with ferritic steel, it has higher plasticity and toughness, no brittleness at room temperature, significantly improved intergranular corrosion resistance and weldability, and maintained the brittleness, high thermal conductivity and superplasticity of ferritic stainless steel at 475℃. Compared with austenitic stainless steel, it has high strength and obviously improved intergranular corrosion resistance and chloride stress corrosion resistance. Duplex stainless steel has excellent pitting corrosion resistance and is also a nickel-saving stainless steel.

4. Martensite stainless steel: high strength, but poor plasticity and weldability.

Commonly used brands of martensitic stainless steel are 1Cr 13, 3Cr 13, etc. Martensite stainless steel has high strength, hardness and wear resistance due to its high carbon content, but its corrosion resistance is slightly poor. Used for some parts with high mechanical performance and general corrosion resistance requirements, such as springs, steam turbine blades, hydraulic machine valves, etc. This kind of steel is used after quenching and tempering. Stainless steel will not cause corrosion, pitting, rust or wear. Stainless steel is also one of the strongest building metal materials. Because stainless steel has good corrosion resistance, it can permanently maintain the integrity of engineering design. Chromium-containing stainless steel also has both mechanical strength and high ductility, which is easy to manufacture and meets the needs of architects and structural designers.

. Most of the use requirements are to keep the original appearance of the building for a long time. When determining the type of stainless steel to be selected, the main considerations are the required aesthetic standards, the corrosiveness of the local atmosphere and the cleaning system to be adopted.

However, more and more other applications only seek structural integrity or impermeability. Such as roofs and side walls of industrial buildings. In these applications, the owner's construction cost may be more important than beauty, and the surface is not very clean.

The effect of using 304 stainless steel in dry indoor environment is quite good. However, in rural and urban areas, if you want to keep its appearance outdoors, you need to clean it frequently. In heavily polluted industrial areas and coastal areas, the surface will be very dirty and even rusty. However, in order to obtain the beautiful effect in outdoor environment, nickel-containing stainless steel must be used. Therefore, 304 stainless steel is widely used in curtain walls, side walls, roofs and other building applications, but in the industrial or marine atmosphere with severe corrosiveness, it is best to use 3 16 stainless steel.

Stainless steel sliding door

Now, people have fully realized the advantages of using stainless steel in structural applications. Some design standards include 304 and 3 16 stainless steel. Duplex stainless steel 2205 has good atmospheric corrosion resistance, high tensile strength and elastic ultimate strength, so it has also been included in European standards.

Product shape

In fact, stainless steel is made according to all standard metal shapes and sizes, and there are many special shapes. The most commonly used products are thin plate and strip steel, and special products are also medium plate, such as hot rolled structural steel and extruded structural steel. There are also round, oval, square, rectangular and hexagonal welded or seamless steel pipes and other forms of products, including profiles, bars, wires and castings. As will be mentioned later, many different commercial surface treatments have been developed to meet the aesthetic requirements of architects. For example, the surface can be highly reflective or dull; Can be smooth, polished or embossed; It can be colored, colored, electroplated or etched on the surface of stainless steel, and can also be drawn to meet various requirements of designers for appearance.

It is easy to keep the surface state. Dust can only be removed by occasional cleaning. Because of its good corrosion resistance, graffiti pollution or similar other surface pollution can also be easily removed. Because stainless steel has many ideal properties required by building materials, it can be said to be unique among metals, and its development continues. In order to improve the performance of stainless steel in traditional applications, the existing types have been improved, and new stainless steel is being developed to meet the strict requirements of advanced building applications. Due to the continuous improvement of production efficiency and quality, stainless steel has become one of the most cost-effective materials chosen by architects. Stainless steel combines performance, appearance and use characteristics, so it will still be one of the best building materials in the world. China Stainless Steel Marketing Network integrates the service platform of stainless steel and stainless steel supply chain information, and provides information and consulting services for members and users around the world by setting up several columns such as stainless steel industry information, industry observation, enterprise management, stainless steel design, stainless steel forum, equipment and materials, exhibition information, stainless steel knowledge and talent recruitment. , through the latest information, database, database, analysis and prediction, communication platform, etc. Provide trade information and seek business opportunities for stainless steel industry and related industries; Spread stainless steel culture and home life art, and provide stainless steel consumption knowledge.