45# seamless steel tube (No. 45 seamless steel tube), here the 45# refers to the steel tube material is 45#. 45# steel is Chinese GB standard high quality carbon steel, which is called S45C in the Japanese standard. American standard is 1045, German standard is C45.

45# seamless steel tube is a high-quality carbon structural steel. The difference between 45# seamless steel tube and 20# seamless steel tube is that its hardness is obviously higher than that of 20# seamless steel tube. The tempering brittleness of 45# seamless steel tube is high. After quenching and tempering, 45# seamless steel tube has good mechanical properties.

Chemical composition of 45# seamless steel tube:
Carbon (C) 0.42 - 0.50%
The content of Si is 0.17 - 0.37%
Mn content: 0.50 - 0.80%
Cr content ≤ 0.25%

45# seamless steel tube is widely used in mechanical parts processing. It can be processed into connecting rod, gear, shaft, bolt, etc. If the wear resistance is considered, heat treatment is required.