Ordinary annealing is also called industrial annealing. The retarding temperature is equivalent to the recrystallization starting temperature of similar deformed titanium alloy rods. The recrystallization temperature of some domestic brands of cast titanium rods and titanium alloy rods. At this time, the structure of the alloy has a certain diffusion activation energy. In order to promote the complete decomposition of some meta-stable b phases, the residual stresses are completely eliminated inside the castings, and at the same time, the alloy is maintained with appropriate strength and plasticity to obtain a uniform structure and energy.
The heat treatment specifications specified in the domestic technical conditions for casting titanium alloys, the selection of the heating and cooling speeds of titanium alloy bar castings during ordinary annealing, should be based on preventing the castings from generating deformation and warpage beyond the allowable range. The annealing temperature should be calculated from the lower limit of the given recrystallization temperature range. The time of heat preservation should be determined according to the wall thickness of the casting and the amount of furnace installed, and the relationship between the wall thickness of the titanium alloy rod casting and the delay-fire holding time. For castings with complex structure that have been welded or repaired many times over a large area, the annealing temperature should be selected to the upper limit of the given temperature range. The internal residual stress of the titanium alloy rod casting after this kind of retarding can be basically completely eliminated. However, for most industrial casting effective alloys, the cooling rate during annealing does not have a great influence on the structure and performance. Therefore, after the casting is annealed, one ship adopts air cooling, which also allows for furnace cooling.
