1. What is the chemical composition range of 35# seamless steel pipe?
Answer: The chemical composition of 35# seamless steel pipe is strictly controlled as follows: C (0.32%-0.40%), Si (0.17%-0.37%), Mn (0.50%-0.80%), P≤0.035%, S≤0.035%. Its carbon content is higher than 10# and 20#, which gives it better strength and hardness, while maintaining a certain degree of toughness.
2. Can 10# seamless steel pipe be used in high-pressure pipeline systems?
Answer: No. 10# seamless steel pipe is low-carbon steel with low tensile strength and yield strength, which cannot bear high pressure. It is only suitable for low-pressure fluid transportation (general pressure ≤1.6MPa), such as domestic water supply pipelines and low-pressure air pipelines. High-pressure pipeline systems should choose high-strength seamless steel pipes such as 20G or 15CrMoG.
3. What heat treatment methods are usually used for 45# seamless steel pipe?
Answer: The common heat treatment methods for 45# seamless steel pipe are quenching and tempering (QT) and normalizing. Quenching and tempering treatment can significantly improve its comprehensive mechanical properties: quenching at 840-860℃, tempering at 550-650℃, which makes the steel pipe have high strength and good toughness. Normalizing treatment (heating to 850-870℃ and cooling in air) is mainly used to refine the grain and improve the uniformity of the structure, which is suitable for general mechanical processing.
4. What is the difference between 20# seamless steel pipe and 20G seamless steel pipe?
Answer: The main difference lies in the standard and application scenario: 20# seamless steel pipe complies with GB/T 8163 standard, which is mainly used for fluid transportation and general structure; 20G seamless steel pipe complies with GB/T 3087 standard, which is a boiler tube special steel with stricter requirements on chemical composition and mechanical properties, and can be used in medium and low pressure boilers (working pressure ≤5.9MPa, working temperature ≤450℃) for steam transportation.
5. What is the application scope of 15CrMoG seamless steel pipe?
Answer: 15CrMoG seamless steel pipe is a low-alloy heat-resistant steel, which contains Cr and Mo elements, so it has good high-temperature strength and oxidation resistance. Its long-term working temperature can reach 550℃, and it is widely used in high-temperature and high-pressure equipment in petroleum, chemical, power and other industries, such as boiler superheater tubes, reheater tubes and high-temperature steam pipelines.
