Research on QU100 Heavy Crane Rail Welding Technology

Research on QU100 Heavy Crane Rail Welding Technology
With the continuous increase of import and export goods in the country, port cranes have become one of the main equipment for hoisting goods in ports. The crane is moving towards large tonnage and high efficiency. The crane rail installation is developed from the traditional rigid fixed rail to the welded joint. In view of the shortcomings of the welding process of the QU100 heavy crane rail, we have explored the QU100 heavy crane rail welding process. The components of QU100 heavy crane rail are sensitive to quenching during the slow cooling process, and the martensite structure is generated in the heat-affected zone to form a brittle hardening zone, which is prone to cracks. At the same time, due to the effect of the tissue stress on the weld metal, it may cause cracks in the overheated zone. During the welding process, part of the base metal is melted into the molten pool, which increases the carbon content of the weld metal and is prone to thermal cracking. The high thermal conductivity of high carbon steel results in a large temperature difference between the weld zone and the base metal zone, and excessive stress concentration occurs during welding, and the tendency of cracking occurs during the slow cooling of the molten pool. When the high carbon steel is welded, the grain growth rate is accelerated due to the excessive temperature, and some of the carbides are distributed at the grain boundaries, which makes the weld brittle and the strength of the welded joint decreases. Since the liquid metal exposed to the air for a long time is easily oxidized by the action of oxygen in the air, strict process measures must be taken to select the appropriate welding parameters to ensure the welding quality.
After the heat treatment of the weld, the scale on both sides of the track weld is removed and PT is detected. After passing the above steps, the pass rate of welds through non-destructive testing is over 97%. Practice has proved that although the QU100 heavy crane rail welding performance is poor and the installation accuracy is high, as long as a reasonable welding process is adopted, the internal structure, performance and installation accuracy of the rail welding can fully meet the design and specification requirements.