15CrMoG seamless steel pipe is an alloy steel pipe widely used in high-temperature and high-pressure environments. Its excellent performance makes it a key material in industries such as power, petrochemicals, and boiler manufacturing. Based on a chromium-molybdenum alloy, this steel pipe is manufactured into a seamless tubular shape through a specific production process. It possesses excellent high-temperature resistance, high-pressure resistance, and corrosion resistance, meeting the requirements of extreme working conditions.
Chemically, the main alloying elements of 15CrMoG seamless steel pipe include chromium and molybdenum, with chromium content approximately 1.00%-1.50% and molybdenum content approximately 0.45%-0.65%. The addition of these two elements significantly improves the high-temperature strength and oxidation resistance of the steel. Chromium forms a dense oxide film on the steel surface, effectively preventing further oxidation, while molybdenum improves the steel's thermal strength and creep strength, allowing it to maintain good mechanical properties at high temperatures. In addition, the steel also contains appropriate amounts of carbon, silicon, manganese, phosphorus, and sulfur, the contents of which are strictly controlled to ensure the overall performance of the steel. In terms of manufacturing process, 15CrMoG seamless steel pipes are mainly manufactured using hot rolling or cold drawing processes. Hot rolling involves heating the steel billet to a suitable temperature, piercing it through a piercing mill, and rolling it into a pipe. This method has high production efficiency and is suitable for mass production. Cold drawing, on the other hand, involves drawing the hot-rolled billet into shape using dies at room temperature, resulting in pipes with higher precision and better surface quality. Regardless of the process used, strict control of parameters such as temperature and deformation is required during production to ensure that the pipe's microstructure and mechanical properties meet standard requirements. Subsequent heat treatment, such as normalizing and tempering, is also necessary to optimize the material's microstructure and properties.
In terms of physical properties, 15CrMoG seamless steel pipes exhibit excellent performance. Their tensile strength is typically between 440-640 MPa, their yield strength is not less than 295 MPa, and elongation can reach over 21%. These mechanical properties enable them to withstand various stresses under high-pressure environments. In terms of high-temperature performance, 15CrMoG seamless steel pipes maintain good strength below 500℃ and can withstand short-term operating temperatures up to 550℃, demonstrating excellent creep resistance. The coefficient of thermal expansion is approximately 12.5 × 10⁻⁶/℃, and the thermal conductivity is 42.7 W/(m·K). These parameters are crucial for the design calculations of high-temperature equipment.
The applications of 15CrMoG seamless steel pipes are extensive. In the power industry, it is widely used in key components such as superheaters, reheaters, and main steam pipes of supercritical and ultra-supercritical power plant boilers. In the petrochemical industry, it is commonly used in high-temperature and high-pressure equipment such as hydrogenation reactors and catalytic cracking units. In boiler manufacturing, it is the preferred material for manufacturing various high-pressure boiler heating surface tubes. Furthermore, it has important applications in nuclear power, metallurgy, and machinery manufacturing industries. These applications all require materials to operate stably for extended periods under harsh conditions such as high temperature, high pressure, and corrosive media; 15CrMoG seamless steel pipes, with their superior performance, fully meet these stringent requirements.
Compared to ordinary carbon steel, 15CrMoG seamless steel pipes have significant performance advantages. Firstly, they have higher high-temperature strength; at the same temperature, their allowable stress is 2-3 times that of carbon steel. Secondly, they have better oxidation resistance, resulting in a longer service life in high-temperature steam environments. Thirdly, they have better microstructural stability and are less prone to deterioration phenomena such as pearlite spheroidization under long-term high-temperature operation. Compared to other alloy steels such as 12Cr1MoVG, 15CrMoG seamless steel pipes have a lower alloy content, making them more cost-effective, while still meeting the requirements of most medium-temperature and high-pressure operating conditions. Compared to higher-grade P91/P92 steels, although their high-temperature strength is slightly lower, their weldability and machinability are better, making them more suitable for certain specific applications.
In practical use, welding 15CrMoG seamless steel pipes requires special attention. Due to the presence of alloying elements such as chromium and molybdenum, cold cracking is prone to occur during welding; therefore, appropriate preheating and post-weld heat treatment measures are necessary. Generally, the preheating temperature is controlled at 150-200℃, and the interpass temperature should not exceed 300℃. Post-weld tempering at 680-720℃ is required to eliminate residual welding stress. Welding materials should be selected using welding wire or electrodes compatible with the base metal, such as E5515-B2. Furthermore, heat input must be controlled during welding to avoid overheating and subsequent performance degradation in the weld area.
From a market perspective, the demand for 15CrMoG seamless steel pipes has steadily increased with the development of industries such as power and petrochemicals. Especially with the promotion of supercritical and ultra-supercritical power generation technologies, the demand for high-performance boiler tubes continues to rise. Major domestic manufacturers include large steel companies such as Baosteel, Tianjin Pipe, and Valin Henggang. These companies, through continuous improvement of production processes and product quality, are already able to meet most of the domestic demand, and some products are even exported to the international market. In the future, with advancements in materials technology, the performance of 15CrMoG seamless steel pipes will be further improved, and their application areas will be further expanded.
In terms of use and maintenance, 15CrMoG seamless steel pipes require regular inspection, especially fittings that operate under long-term high-temperature and high-pressure conditions. Attention should be paid to wall thinning, surface oxidation, and microstructural degradation, with replacement as necessary. Storage should avoid humid environments to prevent corrosion; appropriate protective measures should be taken during transportation to prevent collision damage. Proper use and maintenance can significantly extend the service life of the pipes and improve the safety and economy of equipment operation.
In summary, 15CrMoG seamless steel pipes, as a high-performance alloy steel pipe, play an irreplaceable role in modern industry. Its rational alloy design, mature production process, and reliable performance make it an ideal choice for high-temperature and high-pressure conditions. With the continuous development of my country's industrial technology and the increasing demands on material performance, 15CrMoG seamless steel pipes will undoubtedly play an important role in more fields, providing strong guarantees for the safe and efficient operation of industrial equipment. In the future, through further optimization of composition design and production processes, the performance of this material has room for improvement, and its application prospects are very broad.
