Stainless steel has what material composition

Austenitic stainless steel: stainless steel with austenitic organization at room temperature. Steel containing Cr about 18%, Ni 8% to 10%, C about 0.1%, with a stable austenitic organization. Austenitic chromium-nickel stainless steel, including the famous 18Cr-8Ni steel and on the basis of the increase in Cr, Ni content and the addition of Mo, Cu, Si, Nb, Ti and other elements of the development of high Cr-Ni series steel. Austenitic stainless steel is non-magnetic and has high toughness and plasticity, but the strength is low, it is not possible to make it strengthened by phase change, only through cold working for strengthening. If the addition of S, Ca, Se, Te and other elements, it has good machinability. Such steel in addition to oxidizing acid medium corrosion resistance, if it contains Mo, Cu and other elements can also be resistant to sulfuric acid, phosphoric acid, as well as formic acid, acetic acid, urea and other corrosion. The carbon content of such steel if less than 0.03% or Ti, Ni, can significantly improve its resistance to intergranular corrosion performance. High silicon austenitic stainless steel has good corrosion resistance to nitric acid. As a result of the austenitic stainless steel has a comprehensive and good overall performance, in all walks of life in a wide range of applications.

Ferrite stainless steel: stainless steel in the use of the state of ferrite organization is dominated. Chromium content of 11% ~ 30%, with a body-centered cubic crystal structure. This type of steel generally does not contain nickel, sometimes also contains a small amount of Mo, Ti, Nb and other elements, this type of steel has a large coefficient of thermal conductivity, coefficient of expansion is small, good oxidation resistance, good resistance to stress corrosion and other characteristics, mostly used in the manufacture of corrosion-resistant atmospheric, water vapor, water, and oxidizing acid corrosion of parts. This type of steel exists in poor plasticity, plasticity and corrosion resistance after welding is significantly reduced and other shortcomings, thus limiting its application. The application of extra-oven refining technology (AOD or VOD) can make carbon, nitrogen and other interstitial elements greatly reduced, so that this type of steel to obtain a wide range of applications.

Austenitic - ferrite duplex stainless steel: is austenitic and ferrite organization each about half of the stainless steel. In the case of low C content, Cr content in 18% ~ 28%, Ni content in 3% ~ 10%. Some steels also contain Mo, Cu, Si, Nb, Ti, N and other alloying elements. This type of steel has both austenitic and ferritic stainless steel features, compared with ferritic, plasticity, toughness is higher, no room temperature brittleness, intergranular corrosion resistance and welding performance are significantly improved, while also maintaining a ferritic stainless steel 475 ℃ brittleness and thermal conductivity is high, with superplasticity and other characteristics. Compared with austenitic stainless steel, high strength and resistance to intergranular corrosion and chloride stress corrosion has improved significantly. Duplex stainless steel has excellent pore corrosion resistance, is also a nickel-saving stainless steel.

Martensitic stainless steel: heat treatment can be adjusted through the mechanical properties of the stainless steel, commonly known as a class of hardening stainless steel. Typical grades for Cr13 type, such as 20Cr13, 30Cr13, 40Cr13 and so on. Higher hardness after quenching, different tempering temperatures with different toughness combinations, mainly used for steam turbine blades, cutlery, surgical instruments. According to the difference in chemical composition, martensitic stainless steel can be divided into two categories of martensitic chromium steel and martensitic chromium-nickel steel. According to the different organization and strengthening mechanism, it can also be divided into martensitic stainless steel, martensitic and semi-austenitic (or semi-martensitic) precipitation hardening stainless steel and martensitic aging stainless steel.

Representative steel number, chemical composition, room temperature mechanical properties: martensitic stainless steel on behalf of the steel number for the 12Cr13, 20Cr13, 30Cr13, etc., ferritic stainless steel on behalf of the steel number for the 10Cr17, 10Cr17Mo, etc., austenitic stainless steel on behalf of the steel number for the 06Cr19Ni10 (304), 022Cr19Ni10 ( 304L), 06Cr17Ni12Mo2 (316), 022Cr17Ni12Mo2 (316L), 06Cr18Ni11Ti (321), 06Cr18Ni11Nb (347), etc., duplex stainless steel on behalf of the steel number for the 00Cr26Ni7Mo2Ti.