In the industrial field, seamless steel tubes serve as important structural materials and conveying pipelines, and their material selection directly affects performance and safety reliability. 20#, 45#, and Q345B are three commonly used materials for seamless steel tubes, each with unique characteristics suitable for different working conditions. This article provides a detailed analysis of the differences between these three materials and offers professional selection advice.

Comparison of Material Properties

20# Steel Seamless Steel Tube

20# steel is a high-quality carbon structural steel with a carbon content of approximately 0.17–0.24%. It offers good plasticity and toughness, as well as excellent cold deformation performance. Seamless steel tubes made of this material are typically produced using hot-rolling or cold-drawing processes, providing high formability and weldability. After normalizing treatment, 20# steel seamless tubes achieve a more uniform structure and performance, making them suitable for manufacturing pipeline systems that withstand medium pressure.

45# Steel Seamless Steel Tube

45# steel is a medium-carbon steel with a carbon content of approximately 0.42–0.50%. It offers high strength and hardness. Seamless steel tubes made of this material usually require quenching and tempering treatment (quenching + high-temperature tempering) to achieve good comprehensive mechanical properties. 45# steel seamless tubes exhibit relatively good wear resistance but have poor weldability, requiring preheating and post-heat treatment.

Q345B Low-Alloy Steel Seamless Steel Tube

Q345B is a low-alloy high-strength structural steel containing alloy elements such as manganese, vanadium, and niobium. It offers excellent comprehensive mechanical properties, with a yield strength of up to 345 MPa or higher. Seamless steel tubes made of this material provide good low-temperature toughness and weldability. They are typically produced using hot-rolling processes and are widely used in critical engineering structures.

Selection Guide

Based on Operating Pressure

For medium and low-pressure pipeline systems (P ≤ 6.4 MPa), 20# steel seamless tubes can be selected. For high-pressure pipeline systems (P > 6.4 MPa), 45# steel or Q345B seamless tubes are recommended.

Based on Operating Temperature

All three materials can be used under normal temperature conditions. For low-temperature environments (below -20°C), Q345B seamless tubes should be prioritized due to their excellent low-temperature impact toughness.

Based on Processing Requirements

If extensive cold processing, such as cold bending or flaring, is required, 20# steel seamless tubes with better plasticity should be selected. If the tubes are primarily used for machined parts, 45# steel seamless tubes are a suitable choice.

Professional Manufacturing Advice

Changzhou Tenjan Steel Tube Co., Ltd., as a professional manufacturer of seamless steel tubes, offers high-quality products in various materials to meet customer needs. The company has a comprehensive quality control system to ensure that the material composition and mechanical properties of every seamless tube meet standard requirements.

The company is equipped with advanced testing equipment, such as spectrum analyzers and tensile testing machines, to conduct rigorous inspections of raw materials and finished products, ensuring accurate material composition. Additionally, the company has a professional technical team that can provide customers with material selection advice and technical support.

The 20#, 45#, and Q345B seamless steel tubes produced by Changzhou Tenjan Steel Tube Co., Ltd. are certified under the ISO9001 Quality Management System. The products are widely used in machinery manufacturing, automotive industries, engineering equipment, and other fields. The company guarantees "return and exchange for quality issues," providing customers with reliable product assurance.

Conclusion

Selecting the right material for seamless steel tubes is crucial to ensuring engineering quality and safety. 20# steel is suitable for general pressure pipelines, 45# steel is ideal for applications requiring higher strength, and Q345B is the preferred choice for critical engineering structures. Customers are advised to select the appropriate material based on actual working conditions and consult professional manufacturers when necessary.For more information on seamless steel tubematerials or product selection advice, please contact Changzhou Tenjan Steel Tube Co., Ltd. at 0519-88789990 or visit their official website at www.tenjan.com for professional technical support.