Alloy steel pipe is a kind of seamless steel pipe. Its performance is much higher than that of ordinary seamless steel pipe. Because this steel pipe contains more Cr, its high temperature resistance, low temperature resistance and corrosion resistance are compared with other seamless steel pipes. Upper, so alloy tubes are widely used in petroleum, chemical, electric power, boiler and other industries.
Introduction
Alloy steel pipe is a kind of seamless steel pipe, its performance is much higher than that of ordinary seamless steel pipe, because this steel pipe contains more Cr, its
The high temperature resistance, low temperature resistance and corrosion resistance are not comparable to other seamless steel tubes, so the alloy tubes are widely used in petroleum, chemical, electric power, boiler and other industries.
The principle of purifying hydrogen from 15CrMoG alloy steel pipe is that when the hydrogen to be purified is introduced into one side of the 15CrMoG alloy steel pipe at 300-500 ° C, hydrogen is adsorbed on the wall of the 15CrMoG alloy steel pipe, because the 4d electron layer of palladium lacks two Electron, which can form unstable chemical bonds with hydrogen (the reaction of palladium and hydrogen is reversible). Under the action of palladium, hydrogen is ionized to protons with a radius of 1.5×10 15 m, and the lattice constant of palladium is 3.88. ×10-10m (at 20°C), the 15CrMoG alloy steel tube can be combined with electrons by the action of palladium to re-form hydrogen molecules and escape from the other side of the 15CrMoG alloy steel tube. On the surface of the 15CrMoG alloy steel pipe, the gas that is not dissociated is impermeable, so high purity hydrogen can be obtained by using the 15CrMoG alloy steel pipe.
display method
1 The two digits at the beginning of the steel number indicate the carbon content of the steel, expressed as a few tenths of the average carbon content, such as 40Cr.
2 The main alloying elements in steel, except for individual microalloying elements, are generally expressed in percent. When the average alloy content can be expressed as 2, 3, 4, etc., respectively. For example, 18Cr2Ni4WA.
The alloying elements such as vanadium V, titanium Ti, aluminum AL, boron B, and rare earth RE in steel are all microalloying elements. Although the content is very low, they should be marked in the steel number. For example, in 20MnVB steel. The vanadium is 0.07-0.12% and the boron is 0.001-0.005%.
4 high-quality steel should be added "A" at the end of the steel to distinguish it from ordinary high-quality steel.
15CrMoG high-pressure alloy steel pipe 5 special-purpose alloy structural steel, steel crown (or suffix) represents the symbol of the use of the steel. For example, 30CrMnSi steel for rivet screw, steel grade is expressed as ML30CrMnSi.
Alloy tubes and seamless tubes have both a relationship and a difference, and cannot be confused.
The alloy pipe is defined by the production material (that is, the material). As the name implies, it is the pipe made of alloy; and the seamless pipe is defined by the production process (seamless seamless), which is different from the seamless pipe. There are seam pipes, including straight seam welded pipes and spiral pipes.
Alloy tube material
35CrMo, 16-50Mn, 27SiMn, 40Cr, Cr5Mo, 12Cr1MoV, 12Cr1MovG, 15CrMo, 15CrMoG, 15CrMoV, 13CrMo44, T91, 27SiMn, 25CrMo, 30CrMo, 35CrMoV, 40CrMo, 45CrMo, Cr9Mo, 10CrMo910, 15Mo3, A335P11, P22, P91, T91, steel research 102, ST45.8-111, A106B
3 calculation formula
[(outer diameter - wall thickness) * wall thickness] * 0.02466 = kg / m (weight per meter)
4 performance impact
When the 15CrMoG high-pressure alloy pipe with the same hardenability has the same hardness, the tensile strength is basically the same, and the hardness and the tensile strength are approximately linear.
When the 15CrMoG high-pressure alloy pipe of various compositions is tempered to various hardness values, the hardness value is 400HB (the tensile strength is about 1400MPa), the highest the yield ratio is about 0.9, and the microstructure-to-benchness ratio in the quenched state. have a great impact.
By adjusting the content of the alloying elements which increase the hardenability of the 15CrMoG high-pressure alloy tube, the same hardenability can be obtained, and the same tensile strength and yield strength can be obtained. Therefore, in selecting alloying elements, it is preferred to select elements which have a significant effect on the hardenability and a lower price, such as boron, manganese, chromium, and the like. However, the tempering temperature of the 15CrMoG high-pressure alloy pipe with different alloying elements to be quenched to the same hardness is different, that is, the tempering resistance of various steels is different.
When the 15CrMoG high-pressure alloy tube with the same hardenability has the same hardness, the tensile strength and yield strength are basically the same, but the brittle failure tendency is very different, especially the low temperature impact test. The relationship between hardness and fatigue limit of 15CrMoG high-pressure alloy tubes with different compositions is different. When the hardness is below 35HRC, the fatigue limit and the hardness are linear, and the fatigue limit fluctuation range is 130 MPa. When the hardness exceeds 35 HRC, the fluctuation range of the fatigue limit becomes wider. If the hardness is 55HRC, the fatigue limit fluctuation range is 380MPa.
Three characteristics of 15CrMoG alloy steel pipe structure strengthening Generally, the microstructure of the steel pipe determines the structural properties of the steel pipe, however, the microstructure strengthening determines the microstructure. After the rolling of the cold-rolled alloy steel pipe, the structural structure of various bainite and martensite in the structure changes with the change of the cooling environment, which also causes a great change in the structural properties of the steel pipe. In this way, more steel pipes of varying strength can be obtained to meet different performance requirements.
1. The strengthening of the structure requires the mother phase, that is, the element of the steel pipe should contain the parent phase in which the tissue strengthening occurs.
2. Tissue strengthening is a process, including tissue deformation and tissue diffusion. With the change of cooling environment, the microstructure of alloy steel tube may have two variations, namely diffusion and no diffusion. In low temperature environment, no diffusion determines the organization. The process of deformation; in high temperature environments, diffusion determines the structural changes.
3. There are two important factors in organizational strengthening, namely organizational strain and environmental cooling. For example, in a heating environment or a cooling environment, the microstructure of the alloy steel tube changes gradually as the temperature changes, and the energy state changes from low to high. In addition, looking at the spot of steel pipe, we can know that in alloy steel pipe, a small amount of medium contains extremely fine density. Therefore, when adjusting the structural properties of the steel pipe, it is necessary to pay attention to the structural properties of the alloy steel pipe.
China Hardware Business Network http://news.chinawj.com.cn
Editor: (Hardware Business Network Information Center) http://news.chinawj.com.cn
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