The transition point is above 40 ~ 80℃. The aging treatment temperature is generally 450 ~ 550℃.
To sum up, the heat treatment process of titanium alloy can be summarized as follows:
(1) Stress relief annealing: The purpose is to eliminate or reduce the residual stress generated during the processing. Prevent chemical corrosion and reduce deformation in certain corrosive environments.
(2) Full annealing: The purpose is to obtain good toughness, improve processing performance, facilitate reprocessing and improve dimensional and structural stability.
(3) Solid solution treatment and aging: The purpose is to improve its strength. α titanium alloy and stable β titanium alloy cannot be strengthened by heat treatment and can only be annealed during production. α+β titanium alloys and metastable β titanium alloys containing a small amount of α phase can be further strengthened through solid solution treatment and aging treatment.
In addition, in order to meet the special requirements of workpieces, the industry also uses metal heat treatment processes such as double annealing, isothermal annealing, beta heat treatment, and deformation heat treatment.
Surface treatment is mainly during and after heat treatment to remove oxide scale and various pollutants on the metal surface, reduce the activity of the bare metal surface, and coat the surface of titanium and its alloys with a halide protective layer and various functions. Before and during coating. Coatings are used to improve the properties of metal surfaces, such as protecting against corrosion, oxidation and wear.
The pickling conditions of titanium and its alloys are determined by the type (characteristics) of the oxide layer and the existing reaction layer, which are subject to high-temperature heating processes and processing processes (such as forging, casting, welding, etc.) Effect of rising temperature. At low processing temperatures or high temperatures below about 600X, only a thin oxide layer is formed. At high temperatures, an oxygen-rich diffusion zone forms near a certain oxide layer, and this oxygen-rich diffusion layer must be removed by pickling. A number of different stripping methods can be used: mechanical methods to strip away thick and hard surface layers, stripping methods in molten salt baths and pickling methods in acid solutions.
