Grade 7 titanium alloy, also known as Ti-0.2Pd alloy, is a grade of titanium alloy. It is another class of titanium alloys besides pure titanium (Grade 1-4) and α+β titanium alloys (Grade 5 and 6).
The chemical composition of Grade 7 titanium alloys contains about 0.12-0.25% oxygen (O), up to 0.08% carbon (C), about 0.3% iron (Fe), up to 0.03% nitrogen (N), and about 0.015% of hydrogen (H). In addition, it also contains about 0.12-0.25% palladium (Pd), which is a key ingredient different from other titanium alloys.
Grade 7 titanium alloy has good corrosion resistance and can maintain high corrosion resistance in many strong acid environments. Its strength is relatively low, but it has good weldability and machinability. This alloy is commonly used in the fields of chemical industry, marine, aerospace and medical equipment, and is especially suitable for some applications that require high corrosion resistance.
In general, Grade 7 titanium alloy is a titanium alloy with good corrosion resistance and certain strength, which is suitable for various specific applications.
Titanium alloy Grade 7 chemical composition (%)
Grade 7 Titanium Alloy Physical Properties
Elongation at 50 mm (A5)
Performance characteristics of Grade 7 titanium alloy
Performance characteristics of Grade 7 titanium alloys include:
1 Excellent corrosion resistance: Grade 7 titanium alloy (titanium-palladium alloy) has excellent corrosion resistance in oxidizing media. It also exhibits considerable corrosion resistance in reducing media and is particularly suitable for improving crevice corrosion resistance in media with high chloride ion concentrations. Grade 7 titanium alloy contains 0.2% palladium. In 5% boiling sulfuric acid, the use of Grade 7 titanium-palladium alloy can reduce the corrosion rate from 48.26mm/a (industrial pure titanium) to 0.508mm/a, and the corrosion resistance has increased by about 95 times.
2 Improved crevice corrosion resistance: especially suitable for high chloride ion concentration media, which can improve crevice corrosion resistance.
3 Good high temperature performance: It can maintain stable performance in high temperature environment and has certain heat resistance.
4 Superior strength: It has high strength and good mechanical properties, and is suitable for applications requiring high strength.
5 Lightweight: Titanium alloys have a lower density than other metals, making them ideal for lightweight designs.
6 Good biocompatibility: Al and V elements contained in Grade 7 titanium alloy make Grade 7 titanium alloy a high-quality material for plant biomedicine. Grade 7 titanium alloy has excellent biocompatibility and is widely used in medical fields, such as prosthetic implants and dental implants.
7 Good welding performance: Grade 7 titanium alloy has good processing, forming and welding performance. Since Grade 7 titanium alloy is added a small amount of noble metal Pd to pure titanium, the alloy has excellent corrosion resistance to acidic media. But because of the precious metal palladium, the cost of Grade 7 titanium alloy is relatively high.
Welding of Grade 7 titanium alloys
For the welding of Grade 7 titanium alloys, it is best to use argon arc welding. During the welding process, it is necessary to protect the weld pool and the heat-affected zone with a temperature exceeding 400°C to prevent contamination by gases in the air. If welding cylindrical workpieces, upper and lower protective boxes can be used to provide argon protection. Before welding, it is also necessary to clean the surface of the welding groove.
Heat Treatment of Grade 7 Titanium Alloys
Heat treatment methods for Grade 7 titanium alloys include stress relief annealing and solution treatment. Stress relief annealing can eliminate the internal stress generated during welding and avoid cracking during hydroforming. Annealing can also reduce the strength of the material and improve the plasticity of the material. In order to reduce the pollution of various gases on the surface of Grade 7 materials during heat treatment, anti-oxidation paint can be painted on the surface of the blank.
Solution treatment involves heating a material to a high temperature, maintaining this temperature for a certain period of time, and then rapidly cooling it. This process allows the alloying elements in the material to dissolve in the matrix, increasing the hardness and strength of the material.
The selection of appropriate heat treatment methods and conditions needs to consider the specific requirements and application scenarios of Grade 7 titanium alloys. Please consult a material expert or follow relevant standards and technical guidance before performing heat treatment.
Grade 7 titanium alloy application
Grade 7 titanium alloy is widely used in production equipment parts in the chemical industry due to its excellent corrosion resistance, high strength and excellent formability. The following are some common application areas:
Chemical processing and storage vessels: Grade 7 titanium alloys are commonly used in the manufacture of chemical reactors, tanks, pipes and vessels because of their resistance to many corrosive media, including acids, salts and chemical solutions.
Heat exchangers: Grade 7 titanium alloys can be used to manufacture heat exchangers for heating or cooling fluids, which are widely used in chemical process and energy fields.
Conduit: Grade 7 titanium alloy conduit has excellent corrosion resistance and high strength, and is used for piping systems conveying acidic or alkaline media.
Pumps and valves: Grade 7 titanium alloys can be used to manufacture pumps and valves in the chemical processing industry, suitable for fluid control and delivery of corrosive media.
Accessories and auxiliary equipment: Grade 7 titanium alloy can also be used to manufacture accessories and auxiliary equipment in chemical plants, such as flanges, flanges, seals, etc.
It should be noted that in specific applications, the performance requirements, process requirements and safety of materials should also be considered during the design and manufacturing process to ensure that Grade 7 titanium alloys can meet specific working environments and requirements.