At present, there are three basic welding methods for crane rail, namely aluminum heat welding, contact welding, and air pressure welding. Among them, aluminum heat welding is recognized as a high-efficiency on-site rapid welding method at home and abroad and it’s the only effective welding method for joints. With the continuous advancement of aluminum heat welding technology, the long crane rail of welding crane has been widely promoted and applied in steelmaking span, continuous casting span, finishing span, and desulfurization span. A series of studies have been carried out on the temperature stress, expansion and contraction, and stability of long crane rail, making this technology more mature. For example, the rapid preheating method with the new preheater and the pre-sealing dry type can complete the welding work of a rail joint in 10 minutes, which greatly improves labor productivity and reduces labor intensity. By properly adjusting the distribution of post-weld heat to control the distribution of welding stress, the fatigue strength of the welded joint is increased by 10%-20%. Aluminium heat welding is to combine aluminum powder, iron oxide powder, iron filings and iron alloy or rare earth elements according to a certain proportion to form an aluminum hot flux. After being ignited by high temperature matches, intense chemical reaction and metallurgical reaction occur, during the reaction. Fe is reduced, because the iron specific gravity is larger than the slag sinking on the bottom of the crucible, the slag floats on the upper part, and a large amount of heat is generated at the same time. The high-temperature molten steel is poured into the sand type on the crane rail joint, and the two rail ends are melted, and the molten steel itself is poured. As a filler metal, the two rails are welded and gas-cut, and the forging process flattens the joint portion with the rail and changes the molecular structure of the joint and eliminates the influence of thermal stress.
Aluminum has a strong chemical affinity with oxygen at a sufficiently high temperature to reduce heavy metals from many heavy metal oxides. In order to obtain high quality joint quality, graphite powder can also be added to the aluminum hot flux to adjust the carbon content and add some alloying elements to achieve different performance requirements.