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Types of stainless steel

Jun 10, 2020

Ferritic stainless steel

Contain chromium 15%~30%. Its corrosion resistance, toughness and weldability increase with the increase of chromium content, chloride stress corrosion resistance is better than other types of stainless steel, this category includes Crl7, Cr17Mo2Ti, Cr25, Cr25Mo3Ti, Cr28 and so on. Ferritic stainless steel has high chromium content, good corrosion resistance and oxidation resistance, but poor mechanical properties and process performance. It is mostly used in acid-resistant structures with little stress and as anti-oxidation steel. This type of steel can resist the corrosion of the atmosphere, nitric acid and saline solution, and has the characteristics of high temperature oxidation resistance and small thermal expansion coefficient. It is used in nitric acid and food factory equipment, and can also be used to manufacture parts that work at high temperatures, such as gas turbine parts. .

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Austenitic stainless steel

It contains more than 18% chromium and about 8% nickel and a small amount of molybdenum, titanium, nitrogen and other elements. It has good comprehensive performance and is resistant to various media. Common grades of austenitic stainless steel are 1Cr18Ni9, 0Cr19Ni9 and so on. The Wc of 0Cr19Ni9 steel is less than 0.08%, and the steel number is marked as "0". This type of steel contains a large amount of Ni and Cr, making the steel austenite at room temperature. This type of steel has good plasticity, toughness, weldability, corrosion resistance and non-magnetic or weak magnetic properties. It has good corrosion resistance in oxidizing and reducing media. It is used to make acid-resistant equipment, such as corrosion-resistant containers and equipment. Lining, pipelines, nitric acid-resistant equipment parts, etc., can also be used as the main material of stainless steel watch accessories. Austenitic stainless steel generally adopts solution treatment, that is, the steel is heated to 1050~1150℃, and then water-cooled or air-cooled to obtain a single-phase austenite structure.


Austenitic-ferritic duplex stainless steel

It has the advantages of austenitic and ferritic stainless steel and has superplasticity. Austenitic and ferritic structures each account for about half of stainless steel. When the carbon content is low, the chromium (Cr) content is 18%~28%, and the nickel (Ni) content is 3%~10%. Some steels also contain alloying elements such as Mo, Cu, Si, Nb, Ti, and N. This type of steel has the characteristics of austenitic and ferritic stainless steel. Compared with ferrite, it has higher plasticity and toughness, no room temperature brittleness, and has significantly improved intergranular corrosion resistance and welding performance, while maintaining iron. The 475°C brittleness and high thermal conductivity of plain stainless steel are characterized by superplasticity. Compared with austenitic stainless steel, the strength is high and the resistance to intergranular corrosion and chloride stress corrosion is significantly improved. Duplex stainless steel has excellent pitting corrosion resistance and is also a nickel-saving stainless steel.


Precipitation hardening stainless steel

The matrix is austenite or martensite, and the common grades of precipitation hardening stainless steel are 04Cr13Ni8Mo2Al and so on. It can be hardened (strengthened) by precipitation hardening (also called age hardening).


Martensitic stainless steel

High strength, but poor plasticity and weldability. The commonly used grades of martensitic stainless steel are 1Cr13, 3Cr13, etc. Because of the higher carbon content, they have higher strength, hardness and wear resistance, but the corrosion resistance is slightly poorer. It is used for higher mechanical properties and corrosion resistance. Requires some general parts, such as springs, steam turbine blades, hydraulic valves, etc. This type of steel is used after quenching and tempering. Annealing is required after forging and stamping.


Stainless steel plate and steel belt for pressure equipment

The special stainless steel for pressure vessels has clear requirements for classification and code, size, shape and tolerance, technical requirements, test methods, inspection rules, packaging, signs and product quality certificates. Commonly used brands are 06Cr19Ni10, 022Cr17Ni12Mo2 digital code: S30408, S31603 and so on. Mainly used in sanitary equipment such as food machinery and pharmaceutical machinery.