1. Can 45# seamless steel pipe be used to make high-strength bolts?
Answer: Yes. 45# seamless steel pipe has high strength and hardness (tensile strength 600-750MPa after quenching and tempering), and after precision processing (turning, threading), it can be made into high-strength bolts for mechanical equipment, construction and other fields that require high connection strength. However, it needs to be subjected to strict quenching and tempering heat treatment to ensure the toughness and fatigue resistance of the bolts.
2. Which standard does 15CrMoG seamless steel pipe comply with, and what are its chemical composition characteristics?
Answer: 15CrMoG seamless steel pipe complies with GB/T 3087 (medium and low pressure boiler tubes) or GB/T 5310 (high pressure boiler tubes). Its chemical composition characteristics: C (0.12%-0.18%), Si (0.17%-0.37%), Mn (0.40%-0.70%), Cr (0.80%-1.10%), Mo (0.40%-0.55%), P≤0.035%, S≤0.035%. The addition of Cr and Mo elements improves its high-temperature strength and oxidation resistance.
3. What is the maximum pressure that 20# seamless steel pipe can bear?
Answer: The maximum bearing pressure of 20# seamless steel pipe depends on its wall thickness, outer diameter and working temperature. Under normal temperature (20℃), for a 20# seamless steel pipe with outer diameter 57mm and wall thickness 3.5mm, the maximum allowable working pressure is about 4.0-5.0MPa. The thicker the wall thickness, the higher the bearing pressure; the higher the working temperature, the lower the bearing pressure.
4. What is the application scenario of Q345B seamless steel pipe?
Answer: Q345B seamless steel pipe is a low-alloy high-strength steel pipe, with yield strength ≥345MPa, good comprehensive mechanical properties and welding performance. It is widely used in construction, bridge, machinery, petroleum, chemical and other industries, such as building steel structures, bridge supports, mechanical brackets, medium and high pressure fluid transportation pipelines and offshore platform components.
5. How to detect the quality of seamless steel pipes?
Answer: Common quality detection methods include: ① Chemical composition detection (spectrometer) to check whether the chemical composition meets the standard; ② Mechanical performance test (tensile test, impact test, hardness test) to verify the strength, toughness and hardness; ③ Non-destructive testing (ultrasonic testing, radiographic testing) to detect internal defects (such as cracks, inclusions) and surface defects (such as scratches, pits); ④ Dimensional detection (calipers, micrometers) to check the outer diameter, wall thickness and ovality.
