20G: It is the listed steel number of GB5310-95 (corresponding foreign brands: st45.8 in Germany, STB42 in Japan, and SA106B in the United States). It is the most commonly used steel for boiler steel pipes. The chemical composition and mechanical properties are basically the same as those of 20 steel plates.  The steel has certain strength at normal temperature and medium and high temperature, low carbon content, better plasticity and toughness, and good cold and hot forming and welding properties. It is mainly used to manufacture high-pressure and higher-parameter boiler pipe fittings, superheaters, reheaters, economizers and water walls in the low-temperature section; such as small-diameter pipes for heating surface pipes with a wall temperature of ≤500℃, and water walls Pipes, economizer pipes, etc., large-diameter pipes for steam pipes and headers (economizer, water wall, low-temperature superheater and reheater header) with wall temperature ≤450℃, and pipelines with medium temperature ≤450℃ Accessories etc. Since carbon steel will be graphitized if it is operated for a long time above 450°C, the long-term maximum use temperature of the heating surface tube is best limited to below 450°C. In this temperature range, the strength of the steel can meet the requirements of superheaters and steam pipes, and it has good oxidation resistance, plastic toughness, welding performance and other hot and cold processing properties, and it is widely used. The steel used in the Iranian furnace (referring to a single unit) is the sewage introduction pipe (the quantity is 28 tons), the steam water introduction pipe (20 tons), the steam connection pipe (26 tons), and the economizer header (8 tons). ), desuperheating water system (5 tons), the rest is used as flat steel and boom materials (about 86 tons).

SA-210C (25MnG): It is the steel grade in the ASME SA-210 standard. It is a carbon-manganese steel small-diameter tube for boilers and superheaters, and itis a pearlite heat-strength steel. China transplanted it to GB5310 in 1995 and named it 25MnG. Its chemical composition is simple except for the high content of carbon and manganese, the rest is similar to 20G, so its yield strength is about 20% higher than 20G, and its plasticity and toughness are equivalent to 20G. The steel has a simple production process and good cold and hot workability. Using it instead of 20G can reduce wall thickness and material consumption, Meanwhile improve the heat transfer of the boiler. Its use part and use temperature are basically the same as 20G, mainly used for water wall, economizer, low temperature superheater and other components whose working temperature is lower than 500℃.

SA-106C: It is the steel grade in the ASME SA-106 standard. It is a carbon-manganese steel pipe for large-caliber boilers and superheaters for high temperature. Its chemical composition is simple and similar to 20G carbon steel, but its carbon and manganese content is higher, so its yield strength is about 12% higher than that of 20G, and its plasticity and toughness are not bad. The steel has a simple production process and good cold and hot workability. Using it to replace 20G headers (economizer, water wall, low-temperature superheater and reheater header) can reduce the wall thickness by about 10%, which can save material costs, reduce welding workload, and improve headers The stress difference at start-up.

15Mo3 (15MoG): It is a steel pipe in the DIN17175 standard. It is a small-diameter carbon-molybdenum steel tube for boiler superheater, Meanwhile it is a pearlitic heat-strength steel. China transplanted it to GB5310 in 1995 and named it 15MoG. Its chemical composition is simple, but it contains molybdenum, so while maintaining the same process performance as carbon steel, its thermal strength is better than carbon steel. Because of its good performance and low price, it has been widely adopted by countries all over the world. However, the steel has a tendency of graphitization in long-term operation at high temperature, so its use temperature should be controlled below 510℃, and the amount of Al added during smelting should be limited to control and delay the graphitization process. This steel pipe is mainly used for low-temperature superheaters and low-temperature reheaters, and the wall temperature is below 510℃. Its chemical composition is C0.12-0.20, Si0.10-0.35, Mn0.40-0.80, S≤0.035, P≤0.035, Mo0.25-0.35; normal fire strength level σs≥270-285, σb≥450- 600 MPa; Plasticity δ≥22.

SA-209T1a (20MoG): It is the steel grade in the ASME SA-209 standard. It is a small-diameter carbon-molybdenum steel tube for boilers and superheaters, and it is a pearlite heat-strength steel. China transplanted it to GB5310 in 1995 and named it 20MoG. Its chemical composition is simple, but it contains molybdenum, so while maintaining the same process performance as carbon steel, its thermal strength is better than carbon steel. However, the steel has a tendency to graphitize in long-term operation at high temperature, so its use temperature should be controlled below 510℃ and prevent over-temperature. During smelting, the amount of Al added should be limited to control and delay the graphitization process. This steel pipe is mainly used for parts such as water-cooled walls, superheaters and reheaters, and the wall temperature is below 510℃. Its chemical composition is C0.15-0.25, Si0.10-0.50, Mn0.30-0.80, S≤0.025, P≤0.025, Mo0.44-0.65; normalized strength level σs≥220, σb≥415 MPa; plasticity δ≥30.

15CrMoG: is GB5310-95 steel grade (corresponding to 1Cr-1/2Mo and 11/4Cr-1/2Mo-Si steels widely used in various countries around the world). Its chromium content is higher than that of 12CrMo steel, so it has Higher thermal strength. When the temperature exceeds 550℃, its thermal strength is significantly reduced. When it is operated for a long time at 500-550℃, graphitization will not occur, but carbide spheroidization and redistribution of alloying elements will occur, which all lead to the heat of steel. The strength is reduced, and the steel has good relaxation resistance at 450°C. Its pipe-making and welding process performance is good. Mainly used as high and medium pressure steam pipes and headers with steam parameters below 550℃, superheater tubes with tube wall temperature below 560℃, etc. Its chemical composition is C0.12-0.18, Si0.17-0.37, Mn0.40-0.70, S≤0.030, P≤0.030, Cr0.80-1.10, Mo0.40-0.55; strength level σs≥ in the normal tempered state 235, σb≥440-640 MPa; Plasticity δ≥21.

T22 (P22), 12Cr2MoG: T22 (P22) are ASME SA213 (SA335) standard materials, which are listed in China GB5310-95. In the Cr-Mo steel series, its thermal strength is relatively high, and its endurance strength and allowable stress at the same temperature are even higher than that of 9Cr-1Mo steel. Therefore, it is used in foreign thermal power, nuclear power and pressure vessels. Wide range of applications. But its technical economy is not as good as my country’s 12Cr1MoV, so it is less used in domestic thermal power boiler manufacturing. It is only adopted when the user requests it (especially when it is designed and manufactured according to ASME specifications). The steel is not sensitive to heat treatment, has high durable plasticity and good welding performance. T22 small-diameter tubes are mainly used as heating surface tubes for superheaters and reheaters whose metal wall temperature is below 580℃, while P22 large-diameter tubes are mainly used for superheater/reheater joints whose metal wall temperature does not exceed 565℃. Box and main steam pipe. Its chemical composition is C≤0.15, Si≤0.50, Mn0.30-0.60, S≤0.025, P≤0.025, Cr1.90-2.60, Mo0.87-1.13; strength level σs≥280, σb≥ under positive tempering 450-600 MPa; Plasticity δ≥20.

12Cr1MoVG: It is GB5310-95 listed steel, which is widely used in domestic high-pressure, ultra-high pressure, and subcritical power station boiler superheaters, headers and main steam pipes. The chemical composition and mechanical properties are basically the same as those of 12Cr1MoV sheet. Its chemical composition is simple, the total alloy content is less than 2%, and it is a low-carbon, low-alloy pearlite hot-strength steel. Among them, vanadium can form a stable carbide VC with carbon, which can make the chromium and molybdenum in the steel preferentially exist in the ferrite, and slow down the transfer speed of chromium and molybdenum from ferrite to carbide, making the steel It is more stable at high temperatures. The total amount of alloying elements in this steel is only half of the 2.25Cr-1Mo steel widely used abroad, but its endurance strength at 580℃ and 100,000 h is 40% higher than the latter; and its production process is simple, and its welding performance is good. As long as the heat treatment process is strict, satisfactory overall performance and thermal strength can be obtained. The actual operation of the power station shows that the 12Cr1MoV main steam pipeline can continue to be used after 100,000 hours of safe operation at 540°C. The large-diameter pipes are mainly used as headers and main steam pipes with steam parameters below 565℃, and the small-diameter pipes are used for boiler heating surface pipes with metal wall temperatures below 580℃.

12Cr2MoWVTiB (G102): It is a steel grade in GB5310-95. It is a low-carbon, low-alloy (small amount of multiple) bainite hot-strength steel developed and developed by my country in the 1960s. It has been included in the Ministry of Metallurgy Standard YB529 since the 1970s -70 and the current national standard. At the end of 1980, the steel passed the joint appraisal of the Ministry of Metallurgy, the Ministry of Machinery and Electric Power. The steel has good comprehensive mechanical properties, and its thermal strength and service temperature exceed that of similar foreign steels, reaching the level of some chromium-nickel austenitic steels at 620℃. This is because there are many types of alloying elements contained in steel, and elements such as Cr, Si, etc. that improve oxidation resistance are also added, so the maximum service temperature can reach 620°C. The actual operation of the power station showed that the organization and performance of the steel pipe did not change much after long-term operation. Mainly used as superheater tube and reheater tube of super high parameter boiler with metal temperature ≤620℃. Its chemical composition is C0.08-0.15, Si0.45-0.75, Mn0.45-0.65, S≤0.030, P≤0.030, Cr1.60-2.10, Mo0.50-0.65, V0.28-0.42, Ti0.08 -0.18, W0.30-0.55, B0.002-0.008; strength level σs≥345, σb≥540-735 MPa in positive tempering state; plasticity δ≥18.

SA-213T91 (335P91): It is the steel grade in the ASME SA-213 (335) standard. It is a material for high-temperature pressure parts of nuclear power (also used in other areas) developed by the Rubber Ridge National Laboratory of the United States. The steel is based on T9 (9Cr-1Mo) steel, and is limited to the upper and lower limits of carbon content. , While more strictly controlling the content of residual elements such as P and S, a trace of 0.030-0.070% of N, a trace of strong carbide forming elements of 0.18-0.25% of V and 0.06-0.10% of Nb are added to achieve refinement The new type of ferritic heat-resistant alloy steel is formed by the grain requirements; it is the ASME SA-213 listed steel grade, and China transplanted the steel to the GB5310 standard in 1995, and the grade is set as 10Cr9Mo1VNb; and the international standard ISO/ DIS9329-2 is listed as X10 CrMoVNb9-1. Because of its high chromium content (9%), its oxidation resistance, corrosion resistance, high temperature strength and non-graphitization tendencies are better than low alloy steels. The element molybdenum (1%) mainly improves high temperature strength and inhibits chromium steel. Hot brittleness tendency; Compared with T9, it has improved welding performance and thermal fatigue performance, its durability at 600°C is three times that of the latter, and maintains the excellent high temperature corrosion resistance of T9 (9Cr-1Mo) steel; Compared with austenitic stainless steel, it has small expansion coefficient, good thermal conductivity, and higher endurance strength (for example, compared with TP304 austenitic steel, wait until the strong temperature is 625°C, and the equal stress temperature is 607°C). Therefore, it has good comprehensive mechanical properties, stable structure and performance before and after aging, good welding performance and process performance, high durability and oxidation resistance. Mainly used for superheaters and reheaters with metal temperature ≤650℃ in boilers. Its chemical composition is C0.08-0.12, Si0.20-0.50, Mn0.30-0.60, S≤0.010, P≤0.020, Cr8.00-9.50, Mo0.85-1.05, V0.18-0.25, Al≤0.04 , Nb0.06-0.10, N0.03-0.07; strength level σs≥415, σb≥585 MPa in the positive tempering state; plasticity δ≥20.