The commonly used materials for GB crane rails are mainly U71Mn, U75V, etc. The following is a comparative analysis of them:
Chemical composition
U71Mn: Carbon (C) content is generally 0.65% - 0.76%, and manganese (Mn) content is 1.10% - 1.50%. A higher manganese content can improve the strength and wear resistance of steel, and the carbon content ensures the basic strength of the rail.
U75V: The carbon content is about 0.70% - 0.80%, the vanadium (V) content is 0.04% - 0.12%, and it also contains appropriate amounts of silicon (Si), manganese and other elements. The addition of vanadium can refine the grains and improve the strength, toughness and wear resistance of steel.
Mechanical properties
U71Mn:
High strength, tensile strength can usually reach more than 900MPa, yield strength is around 550MPa, and can withstand large loads during crane operation.
It has good wear resistance, can maintain good surface finish under frequent wheel rolling, and extend the service life of the rail.
It has relatively good toughness, can withstand a certain degree of impact load, and reduce the risk of rail breakage caused by impact.
U75V:
The tensile strength is generally above 950MPa - 1000MPa, and the yield strength can reach above 600MPa. The strength is better than U71Mn, and it can adapt to cranes with heavier loads.
Due to the effect of vanadium, its wear resistance is better than U71Mn. In long-term use, it can better maintain the shape and dimensional accuracy of the track and reduce maintenance costs.
It has good toughness, which is equivalent to or slightly better than U71Mn. It performs well when subjected to impact loads and can effectively prevent brittle fracture of the rail.
Processing performance
U71Mn:
It has good processing performance. In hot processing such as rolling and forging, it shows good plasticity and is easy to form.
The welding performance is good. With the appropriate welding process and welding materials, good quality welding joints can be obtained, which is convenient for on-site installation and maintenance.
U75V:
The hot processing performance is good. Although its processing difficulty is slightly higher than U71Mn due to the presence of vanadium, it can still meet the requirements of industrial production.
The welding performance is also good, but it is necessary to pay attention to controlling the welding parameters during the welding process to prevent the burning of vanadium elements and defects such as cracks in the welded joints.
Corrosion resistance
U71Mn: The corrosion resistance is general. In corrosive environments such as moisture, acid and alkali, it is easy to rust. Effective anti-corrosion measures such as painting and galvanizing are required.
U75V: The corrosion resistance is similar to that of U71Mn. It can meet the use requirements in ordinary environments, but it also needs anti-corrosion treatment in harsh corrosive environments. However, due to its high strength and wear resistance, the comprehensive performance of U75V rails is better in some environments where corrosion and wear work together.
Application scenarios
U71Mn: Suitable for crane rails under general working conditions, such as ordinary workshop cranes, warehouse cranes, etc. Its performance can meet the operating requirements of most conventional cranes, and the cost is relatively low.
U75V: More suitable for cranes with harsh working conditions and large loads, such as port cranes, large metallurgical cranes, etc. Its high strength, wear resistance and good toughness can better adapt to frequent heavy-load operations and complex working environments.