Valve cryogenic treatment principle and its application in industry (two) valve model preparation method detailed diagram

Valve cryogenic treatment principle and its application in industry (two) valve model preparation method detailed diagram

The mechanism of cryogenic treatment is still in the early stage of research. Relatively speaking, the cryogenic mechanism of ferrous metals (iron and steel) has been studied more clearly, while the cryogenic mechanism of non-ferrous metals and other materials is less studied, and is not very clear, the existing mechanism analysis is basically based on iron and steel materials. The microstructure refinement results in the strengthening and toughening of the workpiece. This mainly refers to the fragmentation of the originally thick martensite slats. Some scholars think that the martensite lattice constant has changed. Some scholars believe that the microstructure refinement is caused by the decomposition of martensite and the precipitation of fine carbides.
Upper connection: Valve cryogenic treatment principle and its industrial application (1)
2. Cryogenic treatment mechanism
The mechanism of cryogenic treatment is still in the early stage of research. Relatively speaking, the cryogenic mechanism of ferrous metals (iron and steel) has been studied more clearly, while the cryogenic mechanism of non-ferrous metals and other materials is less studied, and is not very clear, the existing mechanism analysis is basically based on iron and steel materials.
2.1 Cryogenic mechanism of ferrous alloy (steel)
On the mechanism of cryogenic treatment of iron and steel materials, domestic and foreign research has been relatively advanced and in-depth, and everyone has basically reached a consensus, the main views are as follows.
2.1.1 Precipitation of superfine carbides from martensite, resulting in dispersion intensification, has been confirmed by almost all studies. The main reason is that martensite is cryogenic at -196¡æ and due to volume shrinkage, the lattice of Fe
The constant has a tendency to decrease, thus strengthening the driving force of carbon atom precipitation. However, because the diffusion is more difficult and the diffusion distance is shorter at low temperature, a large number of dispersed ultrafine carbides are precipitated on the matrix of martensite.
2.1.2 Change of residual austenite
At low temperature (below Mf point), the residual austenite decompositions and transforms into martensite, which improves the hardness and strength of the workpiece. Some scholars believe that cryogenic cooling can completely eliminate residual austenite. Some scholars found that cryogenic cooling could only reduce the amount of residual austenite, but could not completely eliminate it. It is also believed that cryogenic cooling changes the shape, distribution and substructure of residual austenite, which is beneficial to improve the strength and toughness of steel.
2.1.3 Organization Refinement
The microstructure refinement results in the strengthening and toughening of the workpiece. This mainly refers to the fragmentation of the originally thick martensite slats. Some scholars think that the martensite lattice constant has changed. Some scholars believe that the microstructure refinement is caused by the decomposition of martensite and the precipitation of fine carbides.
2.1.4 Residual compressive stress on the surface
The cooling process may cause plastic flow in defects (micropores, internal stress concentration). During the reheating process, residual stress is generated on the surface of the void, which can reduce the damage of the defect to the local strength of the material. The ultimate performance is the improvement of abrasive wear resistance.
2.1.5 Cryogenic treatment partially transfers the kinetic energy of metal atoms
There are both binding forces that keep atoms close together and kinetic energies that keep them apart. The cryogenic treatment partially transfers the kinetic energy between the atoms, thus making the atoms bond more closely and improving the sexual content of the metal.
2.2 Cryogenic treatment mechanism of non-ferrous alloys
2.2.1 Action mechanism of cryogenic treatment on cemented carbide
It has been reported that cryogenic treatment can improve hardness, flexural strength, impact toughness and magnetic coercivity of cemented carbides. But it makes its permeability go down. According to the analysis, the mechanism of cryogenic treatment is as follows: partial A — Co is changed to ¦Î — Co by cryogenic treatment, and certain residual compressive stress is generated in the surface layer
2.2.2 Action mechanism of cryogenic treatment on copper and copper-based alloys
Li Zhicao et al. studied the effect of cryogenic treatment on the microstructure and properties of H62 brass. The results showed that cryogenic treatment could increase the relative content of ¦Â-phase in the microstructure, which made the microstructure tend to be stable, and could significantly improve the hardness and strength of H62 brass. It is also beneficial to reduce deformation, stabilize size and improve cutting performance. In addition, Cong Jilin and Wang Xiumin et al. of Dalian University of Technology studied the cryogenic treatment of Cu-based materials, mainly CuCr50 vacuum switch contact materials, and the results showed that the cryogenic treatment could make the microstructure significantly refined, and there was mutual dialysis phenomenon at the junction of the two alloys, and a large number of particles precipitated on the surface of the two alloys. It is similar to the phenomenon of carbide precipitated on grain boundary and matrix surface of high-speed steel after cryogenic treatment. In addition, after cryogenic treatment, the resistance to electric corrosion of the vacuum contact material is improved. The research results of cryogenic treatment of copper electrode in foreign countries show that the electric conductivity is improved, the plastic deformation of welding end is reduced, and the service life is increased nearly 9 times. However, there is no clear theory about the mechanism of copper alloy, which may be attributed to the transformation of copper alloy at low temperature, which is similar to the transformation of residual austenite to martensite in steel, and the grain refinement. But the detailed mechanism has not yet been decided.
2.2.3 Effect and mechanism of cryogenic treatment on properties of nickel-based alloys
There are few reports on the cryogenic treatment of nickel-based alloys. It is reported that the cryogenic treatment can improve the plasticity of nickel-based alloys and reduce their sensitivity to alternating stress concentration. The explanation of the authors of the literature is that the stress relaxation of the material is caused by cryogenic treatment, and the microcracks develop in the opposite direction.
2.2.4 Effect and mechanism of cryogenic treatment on the properties of amorphous alloys
As for the effect of cryogenic treatment on the properties of amorphous alloys, Co57Ni10Fe5B17 has been studied in the literature, and it is found that cryogenic treatment can improve the wear resistance and mechanical properties of the amorphous materials. The authors believe that the cryogenic treatment promotes the deposition of non-magnetic elements on the surface, resulting in a structural transition similar to the structural relaxation during crystallization.
2.2.5 Effect and mechanism of cryogenic treatment on aluminum and aluminum-based alloy
Aluminum and aluminum alloy cryogenic processing research is a hotspot in the research of the domestic cryogenic treatment in recent years, Li Huan and chuan-hai jiang et al. The study found that cryogenic treatment can eliminate the residual stress of aluminum silicon carbide composite material and improve its modulus of elasticity, peace Shang Guang fang-wei jin and others found that cryogenic treatment to improve the dimension stability of aluminum alloy, reduce the machining deformation, improve the strength and hardness of the material, However, they did not conduct a systematic study on the related mechanism, but generally believed that the stress generated by temperature increased the dislocation density and caused it. Chen Ding et al. from Central South University of Technology systematically studied the effect of cryogenic treatment on the properties of commonly used aluminum alloys. They found the phenomenon of grain rotation of aluminum alloys caused by cryogenic treatment in their research, and proposed a series of new cryogenic strengthening mechanisms for aluminum alloys.
According to the GB/T1047-2005 standard, the nominal diameter of the valve is only a sign, which is represented by the combination of symbol “DN” and number. The nominal size cannot be the measured valve diameter value, and the actual diameter value of the valve is stipulated by the relevant standards. The general measured value (unit mm) shall not be less than 95% of the nominal size value. The nominal size is divided into metric system (symbol: DN) and British system (symbol: NPS). The national standard valve is metric system, and the American standard valve is British system.
Under the push of industrialization, urbanization, ** and globalization, the prospect of Chinese valve equipment manufacturing industry is broad, the future valve industry **, domestic, modernization, will be the main direction of the future valve industry development. The pursuit of continuous innovation, create a new market for valve enterprises, in order to let enterprises in the increasingly fierce competition in the pump valve industry tide for survival and development.
In the valve production and research and development of technical support, the domestic valve is not backward than the foreign valve, on the contrary, many products in technology and innovation can be comparable to international enterprises, the development of domestic valve industry is moving forward in the direction of modern.
With the continuous development of valve technology, the application of the valve field continues to broaden, and the corresponding valve standard is also more and more indispensable. Valve industry products have entered a period of innovation, not only the product categories need to be updated, the enterprise internal management also needs to be deepened according to the industry standards.
Nominal diameter and nominal pressure of valve
GB/T1047-2005 standard, the nominal diameter of the valve is only a symbol, represented by the combination of symbol “DN” and number, nominal size can not be ** the measured valve diameter value, the actual diameter value of the valve is stipulated by the relevant standards, the general measured value (unit mm) shall not be less than 95% of the nominal size value. The nominal size is divided into metric system (symbol: DN) and British system (symbol: NPS). The national standard valve is metric system, and the American standard valve is British system. The value of metric DN is as follows:
The preferred DN value is as follows:
DN10(nominal diameter 10mm), DN15, DN20, DN25, DN32, DN40, DN50, DN65, DN80, DN100, DN125, DN150, DN200, DN250, DN300, DN350, DN400, DN450, DN500, DN600, DN700, DN800, DN900, DN1000, DN1100, DN1200, DN1400,DN1600, DN1800, DN2000, DN2200, DN2400, DN2600, DN3000, DN3200, DN3500, DN4000
According to the GB/T1048-2005 standard, the nominal pressure of the valve is also an indication, represented by a combination of the symbol “PN” and a number. Nominal pressure (unit: Mpa Mpa) can not be used for calculation purposes, not ** the actual measured value of the valve, the purpose of the establishment of nominal pressure is to simplify the specification of the number of valve pressure, in the selection, design units, manufacturing units and use units are in accordance with the provisions of the data near the principle, the establishment of nominal size is the same purpose. Nominal pressure is divided into European system (PN) and American system (>
PN0.1 (nominal pressure 0.1mpa), PN0.6, PN1.0, PN2.5, PN6, PN10, PN16, PN25, PN40, PN63/64, PN100/110, PN150/160, PN260, PN320, PN420
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Valve model preparation preface
The VALVE model should usually indicate the valve type, drive mode, connection form, structural characteristics, sealing surface material, valve body material and nominal pressure and other elements. The standardization of valve model is convenient for the design, selection and sale of valves. Nowadays, there are more and more types and materials of valves, and the model system of valves is becoming more and more complex. Although China has the unified standard of valve model establishment, but more and more can not meet the needs of valve industry development. Where can not use the standard number of the new valve, each manufacturer can be prepared according to their own needs.
The STANDARD OF Valve Model Preparation Method is applicable to gate valves, throttle valves, ball valves, butterfly valves, diaphragm valves, plunger valves, PLUG valves, check valves, safety valves, pressure reducing valves, traps and so on for industrial pipelines. It includes the valve model and valve designation.
Valve model specific preparation method
The following is the sequence diagram of each code in the standard valve model writing method:
Valve model preparation sequence diagram
Understanding the diagram on the left is the first step to understanding the various valve models. Here is an example to give you a general understanding:
Valve type: “Z961Y-100>
“Z” is unit 1; “9″ is 2 units; “6″ is 3 units; “1″ is 4 units; “Y” is for 5 units; “100″ is 6 units; “I” is for Unit 7
The valve models are: gate valve, electric drive, welded connection, wedge type single gate, carbide seal, 10Mpa pressure, chrome-molybdenum steel body material.
Unit 1: Valve type code
For valves with other functions or with other special mechanisms, add a Chinese word before the valve type code
For alphabetic letters, according to the following table:
Two units: transmission mode
Unit 3: Connection type
Unit Four: Structure type
Gate valve structure form code
Structural form codes for globe, throttle and plunger valves