Control Valve,Flow Control Valve,Pressure Control Valve,Directional Control Valve LIANGGONG VALVE GROUP CO.,LTD , https://www.lgvalvegroup.com
In short, stainless steel is not easy to rust steel, in fact, part of the stainless steel, both stainless steel, but also acid (corrosion resistance). Stainless steel stainless steel and corrosion resistance is due to the surface of the chromium-rich oxide film (passive film) formation. This stainless steel and corrosion resistance is relative. The test shows that the corrosion resistance of steel increases with the increase of chromium content in steel in weak medium such as air and water and in nitric acid and other oxidizing medium. When the chromium content reaches a certain percentage, the corrosion resistance of steel occurs Mutation, that is, from rust to rust, never corrosion to corrosion. Stainless steel classification many ways. According to the organizational structure at room temperature classification, martensite, austenitic, ferritic and duplex stainless steel; according to the main chemical composition, can basically be divided into chromium stainless steel and chrome-nickel stainless steel two systems; There are nitric acid stainless steel, sulfuric acid-resistant stainless steel, seawater resistant stainless steel, etc., according to the type of corrosion resistance can be divided into pitting stainless steel, stainless steel corrosion resistant, resistant to intergranular corrosion of stainless steel; according to functional classification can be divided into no Magnetic stainless steel, free cutting stainless steel, low temperature stainless steel, high strength stainless steel and so on. Due to its excellent corrosion resistance, formability, compatibility and toughness over a wide temperature range, stainless steels have found wide applications in the heavy industry, light industry, household goods and construction and decoration industries . Austenitic stainless steel Austenitic stainless steel at room temperature. Steel containing about 18% Cr, Ni 8% ~ 10%, C about 0.1%, with a stable austenitic structure. Austenitic chrome-nickel stainless steels include the famous 18Cr-8Ni steels and high-Cr-Ni steels that have been developed based on the addition of Cr and Ni and addition of Mo, Cu, Si, Nb and Ti. Austenitic stainless steel is nonmagnetic and has high toughness and plasticity but its strength is low. It can not be strengthened by phase transformation and can only be strengthened by cold working. Such as adding S, Ca, Se, Te and other elements, it has good machinability. In addition to corrosion resistance of such steel acid medium, containing Mo, Cu and other elements are also resistant to sulfuric acid, phosphoric acid and formic acid, acetic acid, urea and other corrosion. If the carbon content of such steel is less than 0.03% or contains Ti, Ni, can significantly improve its resistance to intergranular corrosion. High-silicon austenitic stainless steel nitric acid has good corrosion resistance. Due to its comprehensive and well-integrated properties, austenitic stainless steels have found wide application in all walks of life. Ferritic stainless steel in the use of ferritic-based stainless steel. Chromium content of 11% to 30%, with body-centered cubic crystal structure. Such steel generally does not contain nickel, and sometimes also contains a small amount of Mo, Ti, Nb and other elements, such steel with large thermal conductivity, small expansion coefficient, good oxidation resistance, anti-stress corrosion and other characteristics, and more for the manufacture of atmospheric resistance , Water vapor, water and oxidizing acid corrosion parts. The existence of such poor plasticity, plastic and corrosion resistance after welding significantly reduced the shortcomings, thus limiting its application. The application of furnace refining technology (AOD or VOD) can greatly reduce the gap elements such as carbon and nitrogen, thus making this type of steel widely used. Austenitic-ferritic duplex stainless steel is about half of austenitic and ferritic stainless steel. In the case of lower C, Cr content of 18% to 28%, Ni content of 3% to 10%. Some steel also contains Mo, Cu, Si, Nb, Ti, N and other alloying elements. This type of steel combines the characteristics of austenitic and ferritic stainless steels with higher ductility and toughness than ferrite, no brittleness at room temperature, significant increases in intergranular corrosion resistance and weldability while maintaining Ferritic stainless steel 475 ℃ brittleness and high thermal conductivity, with superplasticity and other characteristics. Compared with the austenitic stainless steel, high strength and resistance to intergranular corrosion and chloride stress corrosion significantly improved. Duplex stainless steel has excellent resistance to pitting corrosion, but also a nickel-saving stainless steel. Martensitic stainless steel stainless steel can be adjusted by mechanical properties of heat treatment, in a nutshell, is a class of hardenable stainless steel. Typical grades for Cr13 type, such as 2Cr13, 3Cr13, 4Cr13 and so on. Pure fire after the higher hardness, different tempering temperature has a combination of different toughness, mainly for steam turbine blades, tableware, surgical instruments. According to the chemical composition of the difference, martensitic stainless steel can be divided into martensitic chromium steel and martensitic chromium nickel steel two types. According to the different organization and strengthening mechanism, can also be divided into martensitic stainless steel, martensite and semi-austenitic (or semi-martensite) precipitation hardening stainless steel and martensitic aging stainless steel. Representative steel, chemical composition, room temperature mechanical properties: Martensitic stainless steel on behalf of the steel No. 1Cr13, 2Cr13, 3Cr13, 4Cr13 and so on, the representative ferritic stainless steel 1Cr17, 1Cr17Ti, 1Cr25, etc., austenitic stainless steel Representative steel No. 1Cr18Ni9Ti, 0Cr18Ni9 (304), 00Cr18Ni9Ti (304L), 0Cr17Ni12Mo2 (316), 00Cr17Ni14Mo2 (316L), 0Cr18Ni11Ti (321), 0Cr18Ni11Nb (347) and so on, the duplex stainless steel is 00Cr26Ni7Mo2Ti and so on. About FRP Phenolic FRP phenolic resin as the substrate, the use of glass fiber reinforced plastic products, it can use all the glass forming process molding, the product has a flame retardant, low smoke, corrosion resistance, low toxicity, temperature High characteristics, widely used in heat-resistant, corrosion-resistant FRP containers, pipes, anti-corrosion lining, air-conditioned train airways, flame retardant cable tray, offshore oil rig grille and petrochemical, light industry, power and other industries thermal insulation Pipeline surface maintenance. Fluoroplastic Introduction Fluoroplastic - the world's best non-metallic corrosion-resistant materials Fluoroplastic (PTFE - F4, FFP - F46) commonly known as "plastic king" by the United States DUPONT CO., LTD then 1938 First developed in the advent of 1949, industrial production, industrial applications from the point of view of 50 years of history, and its real widely used in the pump and valve industry, the time is not long. Fluorine plastic lining corrosion-resistant valve is the FEP F46 or profiles processed by molding or inlaying method placed in steel or iron pump valve pressure parts of the inner wall or the inner and outer surface of the use of its In the anti-corrosive media unique system made into various types of pumps, valves, pipes and other products. In the anti-corrosion materials, fluorine plastic with unparalleled excellent performance, in addition to molten alkali metals, fluorine and aromatic hydrocarbons and concentrated nitric acid corrosion at 170 ℃ above the phenomenon, the remaining concentrations of hydrochloric acid, sulfuric acid, nitric acid , Aqua regia, organic acids, strong oxidants, concentrated, dilute acid alternating, alternating acid and alkali and a variety of organic solvents were inert reaction. Lined in the pump, the valve wall, both to overcome the shortcomings of low strength fluorine plastic materials, but also to solve the pump, valve body material corrosion resistance is poor, high cost. In addition, fluorine plastic addition to excellent chemical stability, its antifouling, anti-sticking, static and dynamic friction coefficient is very small and similar, anti-friction lubrication performance is good, as the valve opening and closing parts of the seal can be Reduce friction between the sealing surface, reduce valve operating torque, improve product life, its use can also be extended to the food, pharmaceutical industry. In addition to PTFE (F4), FEP (F46) and PVDF (F2), the lining material also extends to PE, PP and PVC range of polyolefins to meet the needs of various operating parameters. Our company mainly has two types of fluorine plastic pump products, one for the perfluorinated (fluorine plastic alloy) -type corrosion-resistant pumps, (such as small pumps); one for the full-lining fluorine plastic (F46) corrosion-resistant pumps , (This is a large pump).