GB QU crane rails play a key role in industrial lifting operations, and their hardness is an important indicator for measuring performance. QU crane rails are usually made of alloy steel materials such as U71Mn and U75V. Taking U71Mn as an example, with the appropriate alloy ratio, this material has excellent comprehensive performance. After heat treatment, the hardness is significantly improved, and it can effectively resist the frequent rolling of the wheels when the crane is running.
| Chemical Components % | |||||||||||
| Mark | C | S1 | Mn | P | S | ||||||
| U71Mn | 0.65-0.77 | 0.15-0.35 | 1.0-1.5 | ＜0.040 | ＜0.040 | ||||||
| Chemical Components % | |||||||||||||
| Mark | C | S1 | Mn | P | S | V | |||||||
| U75v | 0.71-0.80 | 0.50-0.70 | 0.75-1.05 | ≤0.025 | ≤0.025 | 0.04-0.12 | |||||||
According to relevant standards, different types of QU crane rails have different requirements for hardness due to different application scenarios and load requirements. For example, QU70 rails are mostly used for cranes with relatively small lifting weights. After quenching and other treatments, the Brinell hardness of the rail head can generally reach HB280-HB320. This hardness range can ensure that the rail has a certain toughness while providing good wear resistance for the frequently contacted rail head, reducing wear and extending the service life of the rail.
As the lifting weight of the crane increases, rails such as QU100 and QU120 used for large and heavy cranes have higher requirements for hardness. The QU100 rail has undergone special high-temperature quenching treatment, and the rail head Brinell hardness can reach HB300 - HB350, and some are even higher. The higher hardness allows the rail to withstand greater wheel pressure and impact force. When lifting heavy objects, the rail surface is not easy to be deformed, indented, and damaged, ensuring the smooth and safe operation of the crane.
In actual applications, the rail hardness must be reasonably matched with the hardness of the crane wheel. If the rail hardness is too high, the wheel wear will increase; conversely, the rail wear will accelerate. Therefore, precise control of the GB QU crane rail hardness is not only related to the durability of the rail itself, but also of great significance to the stability and reliability of the entire crane operation system. It is a key factor in ensuring the efficient and safe development of industrial lifting operations.