Induction heating for annealing of 65mn spring steel

65mn spring steel induction heating is an alternative to conventional gas burner heating method. This kind of heating occurs inside the material, which can achieve high power density, shorten the heating time, and make the furnace body compact. This -JJn thermal method can make the annealing process reach the best condition, and can also process products of different steel grades and different shapes on the same unit. Strip induction heating is divided into longitudinal flux induction heating and transverse flux induction heating. The recrystallization annealing of ferromagnetic steel adopts the combined heating method of longitudinal magnetic flux induction heating and transverse magnetic flux inductor higher than the Curie temperature, which can take advantage of the advantages of these two systems on the same annealing production line.
65mn spring steel induction heating is an alternative to gas heating. Its main technical features are: it occupies a small space and can control the annealing heating temperature and cooling rate within a wide range. For newly developed multi-phase steels, the annealing process is complicated, and it is difficult to completely implement it with current hot-strip processing equipment. It is against this background that the R&D personnel composed of the Department of Iron and Steel Metallurgy, the Department of Electrical Machinery, the Department of Rectification Technology and the Electrical Drive System of the Aachen University of Technology in North Rhine-Westphalia, Germany, and Otto Junker (Otto Junker GmbH) jointly carried out this research project to jointly develop a pilot annealing line for induction heating continuous recrystallization annealing of cold rolled strip steel. The layout of this annealing line is shown in Figure 1. The total length of the annealing line is 21.4m, and the height of the strip annealing furnace is 8.5m. Table 1 shows all the performance data of the pilot annealing line.
65mn spring steel preheating adopts a strong convection furnace method. Due to incomplete gas sealing, the maximum temperature is 750oC, and the operation is limited to non-ferrous metals. The 65mn spring steel enters the air-sealed tunnel upwards through the steering roller under a certain tension and speed. The population lock chamber is isolated from the atmosphere by an air curtain, and a 65mn spring steel centering treatment is performed in a short horizontal section. After further turning, the strip enters the induction furnace end vertically, passes through the furnace zone in a free hanging manner, and enters the cooling zone. There are two inductors in the furnace zone with a total power of 500kW. The spring steel leaves the cooling zone through a mechanical seal roller. However, when non-ferrous metals are annealed, the other one is cheaper, and better heating results can be obtained. For ferromagnetic materials, the longitudinal flux sensor cannot be used above the Curie temperature. But in the pilot annealing line, both types of inductors can be used.