Commonly used heat treatment methods for titanium alloys are annealing, solid solution and aging treatment. Annealing is to remove internal stress, increase plasticity and structural stability, so as to obtain better overall performance. Generally, the annealing temperature of α alloy and (α+β) alloy is 120～200℃ below the (α+β)-→β phase transition point; solution aging treatment is to obtain martensite α by faster cooling in the high temperature zone 'Phase and metastable β phase, and then decompose these metastable phases in the middle temperature region to obtain finely dispersed second phase particles such as α phase or compound, thereby strengthening the alloy. The quenching of (α+β) alloy is generally performed at 40-100℃ below the (α+β)-β transformation point, and the quenching of metastable β alloy is generally 40-80℃ above the (α+β)-β transformation point. conduct. The aging treatment temperature is generally 450-550°C.

In summary, the heat treatment process of titanium alloy can be summarized as follows:

(1) Stress removal annealing: the purpose is to remove or reduce the residual stress generated during processing. Prevent chemical corrosion and reduce deformation in corrosive environments.

(2) Full annealing: the purpose is to obtain good toughness, increase processing performance, facilitate reprocessing, and increase the stability of size and structure.

(3) Solution treatment and aging: In order to increase their strength, α-titanium alloy and stable β-titanium alloy cannot be strengthened by heat treatment, and can only be annealed during production. Through solution treatment and aging treatment, α + β titanium alloy and a small amount of α phase metastable β titanium alloy can be further strengthened.

In addition, in order to meet the requirements of the workpiece, the industry also uses metal heat treatment processes such as double annealing, isothermal annealing, β heat treatment, and deformation heat treatment.

Hastelloy is a nickel-based corrosion-resistant alloy, which is mainly divided into two categories: nickel-chromium alloy and nickel-chromium-molybdenum alloy. Hastelloy has good corrosion resistance and thermal stability, and is mostly used in aviation and chemical fields.

Hastelloy is suitable for various chemical industries containing redox media. The high content of molybdenum and chromium makes the alloy resistant to chloride ion corrosion, and tungsten further improves the corrosion resistance of the alloy. At the same time, the C-27 Hastelloy tube is a material that can block the corrosion of chlorine, hypochlorite and chlorine dioxide solutions. It has outstanding corrosion resistance to high-concentration chloride solutions such as ferric chloride and copper chloride.

Application areas: heat exchangers, bellows compensators, chemical equipment, flue gas desulfurization and denitrification, paper industry, aerospace applications, acidic environment.