Material for boiler tube
Material for boiler tube
Materials suitable for boilers: 20G, SA-210c, SA-106C, 15Mo3, 15CrMoG, T22 (P22), 12Cr1MoVG,12Cr2MoWVTiB,T91, T23, T92, T122, TP304H, TP347H, SUPER304H, HR3C, and so on.
1) 20G: It is a GB5310-2008 steel No. (corresponding foreign brands: St45.8 in Germany, STB42 in Japan, SA106B in the United States). It is the most commonly used steel for boiler pipe, chemical composition and mechanical properties and 20 plates. basically the same. The steel has certain normal temperature and medium and high temperature strength, low carbon content, better plasticity and toughness, and good cold and hot forming and welding performance. It is mainly used to manufacture high-pressure and higher-parameter boiler tubes, superheaters, reheaters, economizers, and water-cooled walls in low temperature sections; for small-diameter tubes, heating surface tubes with wall temperature ≤ 500°C, and water-cooled walls. Pipes, economizer pipes, etc., large-diameter pipes for steam pipes with a wall temperature ≤450°C, headers (economizers, water-cooled walls, low-temperature superheaters, and reheater headers), pipelines with a medium temperature of ≤450°C Attachments, etc.
2) SA-210c (25MnG): It is the steel grade in the ASME SA-210 standard. It is a carbon-manganese steel small-diameter tube and a pearlitic type heat-strength steel for boilers and superheaters. China transplanted it to GB5310 in 1995 and named it 25MnG. Its chemical composition is simple, except carbon and manganese content is higher, the rest is similar to 20G, so its yield strength is about 20% higher than that of 20G, while plasticity and toughness are equivalent to 20G. The production process of the steel is simple and the hot and cold processing performance is good. Using it instead of 20G can reduce the thickness of the wall, reduce the amount of material, and also improve the heat transfer of the boiler. Its use location and use temperature are basically the same as 20G. It is mainly used for water cooling walls, economizers, cryogenic superheaters and other components whose working temperature is lower than 500°C.
3) SA-106C: It is the steel grade in the ASME SA-106 standard and is a carbon-manganese steel pipe used for high-temperature boilers and superheaters. Its chemical composition is simple, similar to 20G carbon steel, but its carbon and manganese content is relatively high, so its yield strength is about 12% higher than that of 20G, and its plasticity and toughness are not bad. The production process of the steel is simple and the hot and cold processing performance is good. Use it instead of 20G to manufacture headers (economizers, waterwalls, cryogenic superheaters, and reheater headers) to reduce wall thickness by approximately 10%. This saves material costs, reduces welding work, and improves the number of headers. Difference in stress at startup.
4) 15Mo3 (15MoG): It is a steel pipe in the DIN17175 standard. It is a small-diameter carbon-molybdenum steel tube for boilers and superheaters, and a pearlitic type heat-strength steel. China transplanted it to GB5310 in 1995 and named it 15MoG. Its chemical composition is simple, but it contains molybdenum, so its thermal strength performance is superior to that of carbon steel while maintaining the same process performance as carbon steel. Because of its good performance and low price, it has been widely adopted by various countries in the world. However, the long-term operation of the steel at high temperatures tends to be graphitized, so its use temperature should be controlled below 510 °C. During the smelting, the amount of Al added should be limited to control and retard the graphitization process. This steel tube is mainly used in low temperature superheater and low temperature reheater, and the wall temperature is below 510°C.
5) SA-209T1a (20MoG): It is the steel grade in the ASME SA-209 standard. It is a carbon-molybdenum steel small-diameter tube and a pearlitic type heat-strength steel for boilers and superheaters. China transplanted it to GB5310 in 1995 and named it 20MoG. Its chemical composition is simple, but it contains molybdenum, so its thermal strength performance is superior to that of carbon steel while maintaining the same process performance as carbon steel. However, the long-term operation of the steel at high temperatures tends to be graphitized, so its use temperature should be controlled below 510 °C and to prevent over-temperature, during the smelting should limit the amount of Al added to control and delay the graphitization process. This steel pipe is mainly used for parts such as water-cooled wall, superheater and reheater, etc. The wall temperature is below 510°C.
6) 15CrMoG: It is a GB5310-95 steel number (corresponding to the 1Cr-1/2Mo and 11/4Cr-1/2Mo-Si steel widely used in various countries in the world), and its chromium content is higher than 12CrMo steel, so it is 500-550. °C has a high thermal strength. When the temperature exceeds 550 °C, its thermal strength is significantly reduced. When it is operated at 500-550 °C for a long period of time, no graphitization occurs, but carbide spheroidization and redistribution of alloying elements are generated, which all lead to the heat of the steel. Reduced strength, good resistance to relaxation at 450°C. Its pipe production and welding process performance is good. Mainly used as high and medium pressure steam pipes and headers with steam parameters below 550°C and superheater pipes with pipe wall temperatures below 560°C. Its chemical composition
The use of this small-diameter steel tube is mainly used for low temperature superheater/reheater, wall superheater and other components.
7) T22 (P22) and 12Cr2MoG: T22 (P22) are ASME SA213 (SA335) specification materials, which are listed in Chinese GB5310-95. In the Cr-Mo steel series, its thermal strength performance is relatively high, and the permanent strength and allowable stress at the same temperature are even higher than 9Cr-1Mo steel, so it is widely used in thermal power, nuclear power and pressure vessels. Applications. The steel tube is not sensitive to heat treatment, has a high permanent plasticity and good welding performance. The T22 small-diameter pipe is mainly used as a superheater and reheater and other heat receiving pipes under the metal wall temperature of 580°C. The P22 large-diameter pipe is mainly used for the superheater/reheater of the metal wall temperature not exceeding 565°C. Box and main steam pipe.
8) 12Cr1MoVG: It is a GB5310-95 nano-standard steel. It is a widely used steel in domestic high-pressure, ultra-high-pressure, subcritical power station boiler superheaters, headers, and main steam conduits. The chemical composition and mechanical properties are basically the same as those of the 12Cr1MoV sheet. Its chemical composition is simple, the total alloy content is below 2%, and it is a low-carbon, low-alloy pearlitic heat-strength steel. Among them, vanadium can form a stable carbide VC with carbon, and preferentially solid solution of chromium and molybdenum in steel exists in ferrite, and slows the transfer rate of chromium and molybdenum from ferrite to carbide, making steel It is more stable at high temperatures. The total amount of alloying elements in this steel is only half that of 2.25Cr-1Mo steel widely used in foreign countries, but at 580°C and 100,000 hours, the permanent strength is 40% higher than that of the latter, and the production process is simple and the welding performance is good. As long as the strict heat treatment process, you can get satisfactory comprehensive performance and thermal performance. The actual operation of the power station shows that the 12Cr1MoV main steam pipe can continue to be used after it has been safely operated for 100,000 hours at 540°C. Its large-diameter pipes are mainly used as headers and main steam conduits with steam parameters below 565°C, and small-diameter pipes are used for boiler heating surface pipes with metal wall temperatures below 580°C.
The use of this steel has good economic benefits. It is the largest steel grade for low-alloy hot-used steel in our plant.
9) 12Cr2MoWVTiB (G102): It is the steel grade in GB5310-95. It is a low-carbon, low-alloy (multiple-element), bainite-type hot-strength steel developed and developed by China in the 1960s. It was incorporated into the Ministry of Metallurgy from the 1970s. The standard YB529-70 and the current national standard, the end of 1980 the steel passed the joint identification of the Ministry of Metallurgy, a machine department and the Ministry of Electric Power. The steel has good comprehensive mechanical properties, its thermal strength and service temperature exceed that of foreign steels of the same type, and it reaches the level of certain chromium-nickel austenitic steels at 620°C. This is because there are many types of alloying elements contained in the steel, and elements such as Cr, Si, etc., which increase the anti-oxidation performance, are also added, so the maximum operating temperature can reach 620°C. The actual operation of the power station shows that the structure and performance of the steel pipe have not changed much after long-term operation. Mainly used as a super high temperature boiler superheater tube and reheater tube with metal temperature ≤ 620 °C.
The power plant is widely used in 200MW and 300MW units, and the main components manufactured are screen superheater, high temperature superheater and high temperature reheater.
10) SA-213 T91 (335P 91): Steel grade in ASME SA-213 (335) standard. It is a material developed by the American Rubber Ridge National Laboratory for use in nuclear power (and other aspects) high-temperature compression parts. The steel is based on the T9 (9Cr-1Mo) steel, in the upper and lower limit carbon limit , more strictly control the content of residual elements such as P and S, while adding a trace amount of 0.030-0.070% of N, and trace amounts of strong carbide forming elements 0.18-0.25% of V and 0.06-0.10% of Nb to achieve refinement Crystal requirements, resulting in a new type of ferritic heat-resistant alloy steel; it is ASME SA-213 listed steel number, China in 1995 the steel was transplanted to the GB5310 standard, the designation as 10Cr9Mo1VNb; and the international standard ISO/ DIS9329-2 is listed as X10 CrMoVNb9-1.
Because of its high chromium content (9%), its anti-oxidation, anti-corrosion properties, high temperature strength and non-graphitization tend to be superior to low alloy steels, elemental molybdenum (1%) mainly improve the high temperature strength, and inhibit the chromium steel Hot brittle tendency; Compared with T9, the welding performance and thermal fatigue performance are improved, its durable strength at 600°C is three times that of the latter, and the excellent high temperature corrosion resistance of T9 (9Cr-1Mo) steel pipe is maintained; Compared with austenitic stainless steels, the coefficient of expansion is small, the thermal conductivity is good, and there is a higher endurance strength (for example, compared with TP304 austenitic steel, wait until the strong temperature is 625°C, and the isothermal stress temperature is 607°C). Therefore, it has good comprehensive mechanical properties, and stable organization and performance before and after aging, with good welding performance and process performance, high durability and oxidation resistance. Mainly used in superheaters and reheaters with metal temperatures ≤ 650°C in boilers.
The power plant introduced this steel pipe from the beginning of the year 90, made a large number of performance tests and process tests, and conducted localized trial production.
11) T23 (HCM2S): it is Japan's Sumitomo Metal Co., Ltd. on the basis of China G102 (12Cr2MoWVTiB), the carbon content is reduced from 0.08-0.15% to 0.04-0.10%, Mo content is reduced from 0.50-0.65% to 0.05-0.30% , increase the amount of W from 0.30-0.55% to 1.45-1.75%, and form a W-Mo based compound solid solution strengthening, add trace Nb and N to form carbonitrides (mainly VC, VN, M23C6 and M7C3 Diffuse precipitation strengthening, and the successful development of low-carbon low-alloy bainite heat-resistant steel, approved by ASME Code Case 2199-1 in recent years, trade name T23. China's G102 has been widely used in domestic large-scale utility boilers.
T23 (HCM2S) steel before and after the aging of the mechanical properties and microstructure difference is small; welding performance is better than China's G102 [9]; corrosion resistance is better; room temperature strength and impact toughness better than G102, the allowable stress It is basically the same. At least equivalent to G102, but better than SA213-T22 and 12Cr1MoV. Generally speaking, HCM2S has many advantages. Since G012 has been successfully used in boilers in China for many years, it is entirely feasible for HCM2S steel to replace G102 in China.
The T23 (HCM2S) steel pipe has good performance. The maximum service temperature is 600°C, and the best use temperature is 550°C. It can be used to manufacture superheaters and reheaters whose metal wall temperatures do not exceed 600°C in large power station boilers.
12) T92 (NF616): On the basis of T91, Japan's Nippon Steel has further refined and improved its components, and adopted a compound-multivariate strengthening method, appropriately reducing the Mo content to 0.30-0.60% and adding 1.50-2.00% of W. And form a W-Mo compound solid solution strengthening of W, adding N to form a solid solution between the gap strengthening, adding V, Nb and N to form carbonitride diffusion precipitation strengthening and adding trace B (0.001-0.006%) to form B The grain boundary strengthens and develops a new type of ferrite heat-resistant alloy steel. This steel is called NF616 in Japan; it is now included in the ASME SA-213 standard.
T92, like T91, has better thermal expansion coefficient and thermal conductivity than austenitic steels. It has excellent long-term strength, high allowable stress, good toughness, and weldability. Its durability strength {permissible stress} is higher than that of T91, and its durable strength {allowable stress} at 650°C is 1.6 times that of T91; it also has good resistance to steam oxidation and welding performance, and is basically the same as T91.
T92 steel pipe performance is excellent, the use of temperature up to 650 °C. It can partially replace the TP304H and TP347H austenitic stainless steel pipes to produce high-temperature superheater and reheater pipes and other pressure components of subcritical, supercritical and even ultra-supercritical power station boilers whose metal wall temperature does not exceed 650°C, avoiding or reducing them. Dissimilar steel joints improve the running performance of the steel pipe. It can also be used as a pressure vessel and steel for nuclear power high pressure parts. The steel will be widely used as the future, the highest temperature zone of existing boilers, and supercritical pressure boiler pipe steel.
13) T122 (HCM12A):it is HCM12 developed by Japan Sumitomo Metal Corporation based on German X20CrMoV121 (in HCM12, the carbon content of X20CrMoV121 is reduced, 1% W and a small amount of Nb are added to the steel to form W-Mo Based on solid solution strengthening and more stable dispersion of fine carbonized niobium, improved precipitation stability, and improved high temperature strength, the composition is further adjusted by increasing the W content to about 2% and decreasing the Mo content to 0.25-0.60%. About 1% of Cu and trace amounts of N and B form a W-Mo composite solid solution strengthening mainly consisting of W, interstitial solid solution strengthening of nitrogen, and diffusion strengthening of copper and carbonitrides. Made of 12% Cr low carbon alloy heat resistant steel. In the tempered state, the main precipitates in the steel are VC, VN, M23C6. In recent years, it has been approved by ASME Code Case 2180-2 and its designation is T122.
The mechanical properties of T122 (HCM12A) steel before and after aging have very little difference; the metallographic structure is similar to the original structure of the base metal; aging has a certain impact on impact toughness, but it still has a certain impact toughness after long-term aging; welding performance is good; Has high tissue stability and high temperature strength, oxidation resistance and corrosion resistance.
Compared with T91, its durability strength {permissible stress} at high temperature of 650°C, oxidation resistance and corrosion resistance are better. Compared with austenitic stainless steels, the durability of austenitic stainless steels at high temperatures Although stress and oxidation resistance are better than HCM12A, the stress corrosion or intergranular corrosion of austenitic steel is a problem. There is no such problem with HCM12A.
T122 (HCM12A) steel pipe has excellent performance. The maximum service temperature of this steel is 650 °C. It can be used to manufacture materials for advanced supercritical boiler units. It can be used to manufacture superheaters and reheaters whose metal wall temperatures do not exceed 650°C in large power station boilers. The steel can partially replace TP304H and TP347H at 600-650°C boiler superheater and reheater, which has good economic value.
14) TP304H: It is a mature steel grade in the ASME SA-213 standard. It contains a lot of Cr and Ni austenitic stainless steels, and 1Cr18Ni9 in China GB5310-95 is similar to this steel. The steel has good tissue stability, high durability, oxidation resistance, and good processing properties such as bending and welding process performance. However, it is sensitive to intergranular corrosion and stress corrosion, and due to the large number of alloying elements, work hardening is easy to occur, which makes the cutting process more difficult; it has a high thermal expansion coefficient and poor thermal conductivity.
Mainly used in the manufacture of subcritical and supercritical pressure parameters of large-scale power generation boilers such as high-temperature superheater, high-temperature reheater, high temperature section of the screen superheater, and a variety of high temperature and high pressure resistant parts; for the pressure parts, the highest work Temperature up to 650 °C; for antioxidant parts, the highest anti-oxidation temperature up to 850 °C. In addition, the steel can also be used to manufacture containers, valves, pipes, etc., and non-magnetic parts requiring corrosion resistance that work in low temperature etching media. However, due to the disadvantages of austenitic steels, TP304H steel may be partially replaced by T92 and HCM12A when used on pressure parts.
15) TP347H: It is also the steel grade in ASME SA-213. It is a Cr-Ni niobium austenitic stainless steel. China GB5310-95 includes this steel under the trade mark 1Cr19Ni11Nb. This steel is also a mature steel grade. Because the steel is austenitic steel stabilized with yttrium, it has good resistance to intergranular corrosion, high durability, good tissue stability and oxidation resistance, in addition to good bending and welding. Performance; its overall performance is better than TP304H. However, due to the large number of alloying elements, like TP304H, work hardening is likely to occur, making the cutting process more difficult; the thermal expansion coefficient is high and the thermal conductivity is poor; therefore when welding with dissimilar steels and using them at high temperatures, two materials must be considered. Expansion coefficient and high temperature strength matching problem.
TP347H steel pipe has excellent performance. Mainly used in the manufacture of subcritical and supercritical pressure parameters of large-scale power generation boilers such as high-temperature superheater, high-temperature reheater, high temperature section of the screen superheater, and a variety of high temperature and high pressure resistant parts; for the pressure parts, the highest work Temperature up to 650 °C; for antioxidant parts, the highest anti-oxidation temperature up to 850 °C. However, due to the disadvantages of austenitic steels, when such heat-resistant steels are used in pressure-retaining parts, it is also possible to partially replace them with T92 and HCM12A.
16) SUPER304H: Based on TP304H by Sumitomo Metal Corporation of Japan and Mitsubishi Heavy Industries Ltd., by lowering the upper limit of Mn content, approximately 3% of Cu, approximately 0.45% of niobium, and trace amounts of N are added to allow the steel to run during service period. A new type of austenitic stainless steel with very high allowable stress is produced by the precipitation of a very fine and diffuse copper-rich phase precipitated in the austenite matrix and the strengthening of NbC, NbN, NbCrN and M23C6. The boiler tube, which has been included in the Japan MITI standard, is likely to be approved by the ASME Code in the near future.
SUPER304H steel has good welding performance, high durability strength {allowable stress}, good tissue stability, good steam oxidation resistance, and good corrosion resistance (almost the same as TP347H). At 600-700°C, its 105-hour sustained strength {permissible stress} is more than 1.3 times that of TP347H steel.
SUPER304H steel pipe has a very high allowable stress and excellent overall performance. The maximum service temperature of this steel is 700 °C. This steel is mainly used in Japan's thermal power plants to manufacture superheater and reheater high temperature sections and other components. Because of its excellent performance, it is an important material for superheater and reheater steel pipes in supercritical unit boilers in the future, and it has good economic value.
17) TP347HFG: A chromium-nickel-nickel austenitic stainless steel that has the same composition as TP347H but is manufactured and processed differently. Sumitomo Japan is facing two problems with TP347H. (One is that the steam side of TP347H will produce oxide layer peeling under the effect of thermal cycle, and then cause obstruction at the bend pipe to cause overheating and failure; second, the peeled oxide will be taken Steam turbines, which cause severe erosion of turbines, were improved: the use of fine niobium carbide (NbC) dissolution and precipitation mechanisms, and the adoption of a new, high heat treatment process at the solution treatment temperature has resulted in the formation of large TP347H grains. Refinement. Room temperature, high temperature mechanical properties and TP347H basically the same. Because the steel is austenitic steel stabilized with yttrium, and the grains are refined, the endurance strength is about 20% higher than that specified by ASME specifications. The welding performance and fatigue performance are much better than those of conventional TP347H steel pipes, and they have better performance. The resistance to intergranular corrosion, good organizational stability and better anti-oxidation and peeling performance, in addition also has a good bend performance; its overall performance is significantly better than TP347H. High temperature corrosion resistance is best in 18-8 stainless steel. In recent years, this steel has been listed in ASME SA213 and it is named TP347HFG.
TP347HFG steel pipe, like TP347H, is mainly used for the production of high-temperature superheaters, high-temperature reheaters, high-temperature sections of screen superheaters, and various high-temperature and high-pressure pipe fittings for large-scale power generation boilers with subcritical and supercritical pressure parameters. Pressure parts, the maximum working temperature up to 650 °C; for anti-oxidation parts, the highest oxidation temperature up to 850 °C. Because its comprehensive performance is much better than TP347H, it will be widely used in the future.
18) HR3C (Fire SUS310JITB): Austenitic stainless steel with high Cr and Ni content developed by Japan Sumitomo Metal Co., Ltd., which has been incorporated into Japan's MITI specifications, and its designation is "Fire SUS310JITB", which was approved by ASME Code Case 2115 in recent years ( Not yet named). Due to the addition of a large amount of Cr, Ni, and more Nb and N to the steel, the tensile strength of the steel is higher than that of conventional 18-8 stainless steel, and the durability strength and allowable stress are much higher than those of the conventional 18-8 stainless steel. And TP310 steel, high temperature corrosion resistance is much better than the steel containing less Cr, and excellent resistance to steam oxidation. This steel is very close to TP310CbN in ASME SA213.
Mainly used for manufacturing high-temperature superheater, high-temperature reheater, screen superheater high temperature section and various high temperature resistant, high pressure or corrosion fittings of large-scale power generation boiler or circulating fluidized bed boiler for producing subcritical and supercritical pressure parameters. . Because its comprehensive performance is much better than 18-8 stainless steel, it will be widely used in the future.
19) NF709 (20Cr-25Ni-Mo-Nb-Ti-NB): Japan's Nippon Steel strictly controls impurities on the basis of conventional austenitic stainless steels, further improving and improving the composition, and adopting compound-multivariate strengthening methods. A new type of austenitic stainless steel specially developed for supercritical unit boilers. In this steel, Ni is increased to about 25%, Cr is increased to about 20%, 1.50% of Mo, 0.30% of Nb, 0.10% of Ti, N (0.006%), and a small amount of B (0.003%) are added. . Formation of austenite stability with Cr and Ni, composite solid-solution strengthening with N-Mo, carbonitride diffusion-precipitation strengthening of Nb-Ti, and grain boundary strengthening of B to increase its high temperature durability; and Cr, Ni The increase in the amount increases its resistance to steam oxidation, and Cr improves its resistance to soot corrosion; Cr and Ni prevent the formation of intermetallic compounds and Nb-Ti weakens intergranular precipitation to increase the impact toughness of the material. Due to the effect of these elements, its 105-hour permanent strength at 700 °C reaches 88 MPa; its oxidation resistance and corrosion resistance are three times that of 17-14CuMo steel; its weldability is comparable to that of conventional 18-8 stainless steels such as TP347H and TP310S. The same; the welding head has the same durability as the parent material.
Mainly used in the manufacture of supercritical pressure parameters of large-scale power generation boiler or circulating fluidized bed boiler high-temperature superheater, high-temperature reheater, high temperature section of the screen superheater and a variety of high temperature, high pressure or corrosion fittings. Because its comprehensive performance is much better than 18-8 stainless steel, it will be widely used in the future.
