The main type of stainless steel

Stainless steel is often divided into: martensitic steel, ferritic steel, austenitic steel, austenitic ferritic (two-phase) stainless steel and precipitation hardening stainless steel, etc. In addition, according to the composition can be divided into: chromium stainless steel, chromium nickel stainless steel and chromium manganese nitrogen stainless steel. There are special stainless steel for pressure vessels "GB24511_2009_ pressure equipment with stainless steel plate and steel belt".

Ferrite stainless steel

Contains 15% ~ 30% chromium. Its corrosion resistance, toughness and weldability are improved with the increase of chromium content. The resistance to chloride stress corrosion is better than other kinds of stainless steel. Crl7, Cr17Mo2Ti, Cr25, Cr25Mo3Ti, Cr28 and so on belong to this category. Because of its high chromium content, ferritic stainless steel has good corrosion resistance and oxidation resistance, but its mechanical and technological properties are poor. It is mostly used for acid-resistant structures with little force and as anti-oxidation steel. This kind of steel can resist the corrosion of atmosphere, nitric acid and brine solution, and has the characteristics of high temperature oxidation resistance, low thermal expansion coefficient and so on. It is used for nitric acid and food factory equipment, and can also make parts working at high temperature, such as gas turbine parts.

Austenitic stainless steel

Chromium content is more than 18%, but also contains about 8% nickel and a small amount of molybdenum, titanium, nitrogen and other elements. Good comprehensive performance, can withstand the corrosion of a variety of media. Austenitic stainless steel commonly used brands are 1Cr18Ni9, 0Cr19Ni9 and so on. Wc&lt of 0Cr19Ni9 steel; 0.08%, marked with "0" in steel number. Such steels contain large amounts of Ni and Cr, giving the steel an austenitic state at room temperature. This kind of steel has good plasticity, toughness, weldability, corrosion resistance and no magnetic or weak magnetic, in oxidation and reducing medium corrosion resistance are good, used to make acid resistant equipment, such as corrosion resistant vessels and equipment lining, pipeline, nitric acid resistant equipment parts, but also can be used as the main material of stainless steel watch jewelry. Austenitic stainless steel is generally treated with solid solution, that is, the steel is heated to 1050 ~ 1150℃, and then cooled by water or air to obtain single-phase austenitic structure.

Austenitic ferritic stainless steel

It has the advantages of austenitic and ferritic stainless steel and has superplasticity. Austenitic and ferritic structures each comprise about half of stainless steel. At low carbon levels, chromium (Cr) content ranges from 18% to 28% and nickel (Ni) content from 3% to 10%. Some steels also contain Mo, Cu, Si, Nb, Ti, N and other alloying elements. This kind of steel has the characteristics of austenitic and ferritic stainless steel, compared with ferritic, plasticity, toughness is higher, no room temperature brittleness, intercrystalline corrosion resistance and welding performance are significantly improved, but also maintain the ferritic stainless steel 475℃ brittleness and high thermal conductivity, with the characteristics of superplasticity. Compared with austenitic stainless steel, it has higher strength and better resistance to intergranular corrosion and chloride stress corrosion. Duplex stainless steel has excellent corrosion resistance, is also a nickel stainless steel.

Precipitation hardened stainless steel

Matrix for austenitic or martensite structure, precipitator-hardened stainless steel commonly used brand 04Cr13Ni8Mo2Al, etc. Stainless steel that can be hardened by precipitation hardening (also known as age hardening).

Martensite stainless steel

High strength, but poor plasticity and weldability. The commonly used brands of martensitic stainless steel are 1Cr13, 3Cr13, etc., because of the higher carbon content, it has higher strength, hardness and wear resistance, but the corrosion resistance is slightly poor, used for some parts with higher mechanical properties and general corrosion resistance requirements, such as springs, turbine blades, hydraulic press valves. This kind of steel is used after quenching and tempering treatment. Annealing is required after forging and stamping.

Stainless steel plates and strips for pressure equipment

Special stainless steel for pressure vessels, its classification and code, size, shape and allowable deviation, technical requirements, test methods, inspection rules, packaging, marking and product quality certificate have clear requirements. The commonly used brands are 06Cr19Ni10 and 022Cr17Ni12Mo2. The number code is S30408 and S31603. Mainly used for food machinery, pharmaceutical machinery and other sanitary equipment.