Models of Stainless Steel
Stainless steel is often classified according to the state of the organization: martensitic steel, ferritic steel, austenitic steel, austenitic-ferritic (duplex) stainless steel, and precipitation hardened stainless steel. In addition, it can be divided into: chromium stainless steel, chrome nickel stainless steel and chromium manganese nitrogen stainless steel. There is also a special stainless steel for pressure vessels "GB24511_2009_ stainless steel plate and steel strip for pressure equipment".
Austenitic stainless steel
Containing more than 18% chromium, it also contains about 8% nickel and a small amount of molybdenum, titanium, nitrogen and other elements. Good overall performance, resistant to a variety of media corrosion. Commonly used grades of austenitic stainless steels are 1Cr18Ni9, 0Cr19Ni9 and the like. 0Cr19Ni9 steel has Wc<0.08%, and the steel number is marked as “0”. This type of steel contains a large amount of Ni and Cr, which makes the steel austenitic 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 both oxidizing and reducing media and is used to make acid-resistant equipment.
Such as corrosion-resistant containers and equipment linings, pipelines, equipment parts resistant to nitric acid, etc., can also be used as the main material of stainless steel watches and clocks. Austenitic stainless steels are generally treated by solution treatment, that is, the steel is heated to 1050 to 1150 ° C, and then water-cooled or air-cooled to obtain a single-phase austenite structure.
Austenitic - ferritic duplex stainless steel
It combines the advantages of austenitic and ferritic stainless steels and has superplasticity. Austenitic and ferrite structures each account for about half of the stainless steel. In the case of a lower C content, the Cr content is between 18% and 28%, and the Ni content is between 3% and 10%. Some steels also contain alloying elements such as Mo, Cu, Si, Nb, Ti, and N. This type of steel combines the characteristics of austenite and ferritic stainless steel. Compared with ferrite, it has higher plasticity, toughness, no room temperature brittleness, and improved intergranular corrosion resistance and weldability.
At the same time, it also maintains 475°C brittleness and high thermal conductivity of ferritic stainless steel, which is characterized by superplasticity. Compared with austenitic stainless steel, it has high strength and resistance to intergranular corrosion and chloride stress corrosion resistance. Duplex stainless steel has excellent pitting corrosion resistance and is also a nickel-saving stainless steel.
Precipitation hardening stainless steel
The base body is austenite or martensite structure, and the common grades of precipitation hardening stainless steel are 04Cr13Ni8Mo2Al and the like. It can be treated to hard (strong) stainless steel by precipitation hardening (also known as age hardening).
Martensitic stainless steel
High strength, but poor plasticity and weldability. The commonly used grades of martensitic stainless steels are 1Cr13, 3Cr13, etc., because of the high carbon content, they have high strength, hardness and wear resistance, but the corrosion resistance is slightly poor, which is used for high mechanical properties and corrosion resistance. General parts are required, such as springs, steam turbine blades, hydraulic press valves, etc. This type of steel is used after quenching and tempering. Annealing and annealing are required after stamping.
Stainless steel plate and steel belt for pressure equipment
Stainless steel for pressure vessels has clear requirements for classification and code, size, shape and tolerance, technical requirements, test methods, inspection rules, packaging, marking and product quality certificates. Commonly used brands are 06Cr19Ni10, 022Cr17Ni12Mo2 digital code: S30408, S31603 and so on. Mainly used in food machinery, pharmaceutical machinery and other sanitary equipment.