How to anneal the titanium alloy material after cold rolling?
The annealing conditions should be set according to the processing method and application of the product, and the structure after annealing is generally a uniform equiaxed structure. Because titanium is easily oxidized, an oxide film will be formed in a trace oxygen-containing atmosphere at high temperature, and tempering color will appear. Therefore, the annealing of cold-rolled titanium coils should be carried out in a vacuum annealing furnace. According to the application, it is sometimes carried out in an atmospheric annealing furnace, and then pickled with an alkali molten salt to remove the surface scale.
Before vacuum annealing, the cold-rolled coil must be cleaned to completely remove grease such as rolling oil, and the grease is generally washed with alkali. The cleaned cold-rolled coils are heated after vacuum exhaust in the vacuum annealing furnace, and the temperature rise should be carried out in stages to ease the temperature difference between the inside and outside of the coil. After evacuating for a certain period of time, replace it with helium, and stir it with a forced fan to make it produce convection heat conduction and uniform temperature. At 400~500°C, vacuum exhaust should be maintained to obtain a cleaner surface. The annealing temperature is 600~650℃ for 5~10h, plus the heating time and cooling time, the processing time of one furnace is about 10~50h.
The temperature of atmospheric annealing is 700~800℃, and the holding time is short. The catenary type annealing furnace can produce coils with good flatness, and can also reduce the orthopedic load of the finishing process. After atmospheric annealing, use alkali molten salt (about 500°C) to remove phosphorus, and then pickle. After the final annealing, the material should be flattened or corrected according to the needs, and then trimmed, cut into strips, cut into boards, and shipped out after surface quality inspection.