What is the super stainless steel, what are the purposes?
There are many kinds of stainless steel, common, 304.
316, etc. , for the stainless steel do you know, in what place?
Super stainless steel, nickel base alloy is a kind of special stainless steel, first in terms of chemical composition, unlike ordinary stainless steel, is refers to the high nickel, high chromium and high molybdenum a high alloy stainless steel.
According to the microstructure characteristics of stainless steel material, the stainless steel is divided into super ferritic stainless steel, super austenitic stainless steel, super martensitic stainless steel and super duplex stainless steel type.
A, super ferritic stainless steel inherited the common ferritic stainless steel with high intensity, good oxidation resistance, good resistance to stress corrosion, etc, at the same time improve the ductility of ferritic stainless steel & ndash;
Brittle transition, are sensitive to intergranular corrosion and low toughness of weld states such as limitations.
Refining technology, are adopted to decrease the content of C and N, add the stabilization and weld annealed metal elements, can obtain high Cr, Mo and ultra low C, N super ferritic stainless steel, ferritic stainless steel in corrosion resistance, resistance to chloride pitting and crevice corrosion and so on applications has entered a new stage.
Second, super austenitic stainless steel on the basis of common austenitic stainless steel, by increasing the purity of alloy, increase the number of beneficial elements, reduce the content of C, to prevent the precipitation Cr23C6 intercrystalline corrosion, good mechanical properties, process performance and local corrosion resistance, and replace the Ti stabilization of stainless steel.
Three, super martensitic stainless steel can be hardened stainless steel, high hardness, strength and wear resistance, but poor toughness and weldability.
Ordinary martensitic stainless steel without sufficient ductility, is sensitive to stress in the deformation process, cold forming more difficult.
By reducing carbon content, increase the nickel content, super martensitic stainless steel can be obtained.
In recent years, countries in the development of low carbon and low nitrogen super martensitic steel invests a lot, developed a number of different USES of super martensitic steel.
Super martensitic steel has been in the oil and gas production, storage and transportation equipment, hydraulic power generation, chemical industry and is widely used on high temperature pulp production equipment.
Four, nitrogen alloying N as alloying element in stainless steel, stainless steel can improve the stability of austenite, the proportion of the balance of dual phase steel, without affecting the plasticity and toughness of steel increase strength and corrosion resistance of steel, and can part instead of Ni in stainless steel.
In the dual phase steel, N delay dispersion intermetallic compounds precipitate;
In martensitic steel, N distribution on the grain boundary, and other elements to form nitrides can improve the hardening ability, prevent the high temperature tempering austenite and ferrite grain growing up.
In recent years the development of high N content of austenitic stainless steel, namely austenitic stainless steel, high strength non-magnetic has the high temperature strength, it will be widely as a low temperature superconducting materials, high corrosion resistance and non-magnetic materials applications.
Five, super duplex stainless steel of this kind of steel is developed in the late 1980 s, the brand is mainly SAF2507, UR52N, Zeron100, characterized by low C content, contains high Mo and N, steel ferrite phase content was 40% ~ 45%, and has excellent corrosion resistance.
Six, noble and pure purification stainless steel at present domestic stainless steel plant caused by the inclusion of product scrap rate is as high as 20% above.
Therefore, stainless steel smelting process of the nobleness of purification for the center with inclusion control more and more cause the attention of people.
In the process of stainless steel smelting, endogenous inclusions in deoxidization, alloying, and steel liquid crystal.
Finished product foreign inclusions in molten steel smelting, casting and transport.
In order to obtain high cleanliness of stainless steel, must pay attention to the charging material, deoxidizer and deoxidation system, refining and continuous casting system.
Which is the famous steel containing 6% Mo (
, this kind of steel has good resistance to local corrosion performance, in the sea water, air, there is gap, low speed under the condition of scour, good resistance to pitting corrosion performance (
Stress corrosion resistance and good performance, is the substitute material Ni base alloy and titanium alloy.
Secondly in high temperature or corrosion resistance on the performance of a more excellent high temperature or corrosion resistance, is 304 stainless steel can not be replaced.
In addition, from the classification of stainless steel, special stainless steel microstructure is a stable austenitic microstructure.
Because of this special stainless steel is a kind of high alloy material, so in the manufacturing process is very complex, general people can only rely on the traditional process to make this kind of special stainless steel, such as perfusion, forging, rolling, and so on.
Seven, functional stainless steel along with the change of market demand, all kinds of stainless steel with special USES and special features appear constantly.
No Ni austenitic stainless steel such as biomedical materials mainly for Cr -
Ni austenitic stainless steel, has a good biocompatibility, Ni containing 13% ~ 15%.
Ni is a sensitization factor and has teratogenic, carcinogenic harm to organisms.
Containing Ni stainless steel implanted in the body use for a long time, will gradually be destroyed and release the Ni ions.
When Ni ion concentration near the implantation in the human body tissue, may induce toxic effect, adverse reactions such as cell damage and inflammation.
The Chinese Academy of Sciences institute of metal Cr - development
N type medical no Ni austenitic stainless steel, through biological compatibility test, the performance is better than that of Cr - the current clinical use
Ni austenitic stainless steel.
Again such as antibacterial stainless steel, with the improvement of people's living standard, people to their environment and their own health more and more attention, which promoted the research and development of antibacterial materials.