TC4 alloy is a medium-strength α-β type two-phase titanium alloy containing 6% of α-stable element Al and 4% of β-stable element V. In the aerospace industry, the alloy has excellent comprehensive properties and has been widely used. The alloy can work at a temperature of 400°C for a long time, and is mainly used to manufacture fans and compressor discs and blades of engines, as well as important load-bearing components such as beams, joints and bulkheads in aircraft structures.
The main semi-finished products of TC4 titanium alloy include bars, forgings, thick plates, thin plates, profiles and wires. The alloy is usually in the annealed state, and can also be strengthened by solution aging treatment, but the hardened cross section generally does not exceed 25mm.
The alloy has good technological plasticity and superplasticity, and is suitable for various pressure forming. In addition, welding and machining of this alloy can be performed in various ways.
Chemical composition of TC4 titanium alloy (%)
material | TC4 | |||||||||
chemical composition | Fe | ハ | N | V | Al | H | O | other single | Total other | ティ |
≦0.3 | ≦0.08 | ≦0.05 | 3.5-4.5 | 5.5-6.75 | ≦0.015 | ≦0.2 | ≦0.1 | ≦0.4 | margin | |
Mechanical Properties of TC4 Titanium Alloy
material | TC4 | |||
mechanical properties | 抗張力 | 降伏強さ | rate of reduction in area % | hardness |
895 MPa | 825 MPa | 10 | 330-390 HV | |
Physical Properties of TC4 Titanium Alloy
TC4 | |
密度 | 4.428g/cm3(0.160lb/in3) |
弾性係数 | 105-116Gpa (15.2-16.8 psi x 106) |
β commutation point | 955+/-15℃(1825+/-25℉) |
Liquid point | 1655+/-20℃(3011+/-35℉) |
Solid phase point | 1605+/-10℃(2920+/-20℉) |
Resistivity | ~1.5μΩ*m(-250℃) |
Melting and Casting Process of TC4 Titanium Alloy
The smelting process of the ingot should be smelted in a vacuum consumable electrode electric arc furnace at least twice. Raw materials for engine rotor parts should be melted three times. Alloying element V should be added in the form of A1-V master alloy. It is forbidden to use argon tungsten arc welding to weld consumable electrodes, but argon shielded plasma welding method should be used.
Oxidation Resistance of TC4 Titanium Alloy
As the heating temperature increases, the oxide film formed by TC4 titanium alloy will become thicker, but its protection will become worse. When the alloy was heated at 700 °C for 2 hours, the thickness of the oxide film reached 25 μm. When heated at a temperature above 800°C, the formed oxide layer will be denser. When the alloy was heated at 1000°C for 1 hour, the thickness of the oxide layer reached 0.65mm.
TC4 welding performance
1) TC4 alloy can be welded by argon arc welding, spot welding, brazing, electron beam welding and plasma welding, and the strength of the welded joint is basically similar to that of the base metal.
2) For the stress relief annealing of TC4 alloy after welding, it is carried out at 550-650°C, which can eliminate 70%-80% of welding stress. For the welding of plate parts, it is best to carry out stress relief annealing in a vacuum furnace or a protective atmosphere furnace.
3) TC4 alloy has excellent diffusion bonding characteristics, and the diffusion bonding process must be carried out in a vacuum environment. The typical diffusion bonding process parameters are: heating temperature 820-1040°C, pressurization pressure 35-70MPa, holding time 0.5-6 hours.
TC4 Titanium Alloy Heat Treatment Process
TC4 titanium alloy is a widely used titanium alloy, which is often used in aerospace, shipbuilding, automobile and other fields. Heat treatment is an indispensable part in the processing of titanium alloys. It can improve the mechanical properties of titanium alloys, improve their strength, hardness and corrosion resistance.
The heat treatment process of TC4 titanium alloy usually includes the following steps:
1) Annealing
Plates: annealing at a temperature of 700-850°C for 0.5-2 hours, followed by natural cooling. Bars and forgings: Annealing at a temperature of 700-800°C for 1-2 hours, followed by natural cooling.
2) Vacuum annealing
Vacuum annealing is carried out at a temperature of 700-800°C for 0.5-2 hours, and then the temperature in the furnace is cooled to below 200°C, allowing natural cooling after being released from the furnace. The absolute pressure in the furnace should not exceed 0.09Pa.
3) Solution treatment
Solution treatment is carried out at a temperature of 910-940° C. for 0.5-2 hours, and then water quenching.
4) Aging
Aging treatment is carried out at a temperature of 520-550°C for 2-4 hours, followed by natural cooling.
5) Stress relief annealing
Complete stress relief annealing: Annealing at 600-650°C for 1-4 hours, followed by natural cooling. Incomplete stress relief annealing: annealing at a temperature of 500-600°C for 0.5-3 hours, followed by natural cooling. Stress relief annealing can be performed in an air or vacuum furnace.
TC4 titanium alloy surface treatment process
1) In order to enhance the fatigue resistance of titanium alloy parts, shot peening can be carried out. Generally, steel shot with a diameter of 2-5mm can generate a compressive stress of about 785MPa on the surface and reach a surface strengthening depth of about 200μm. Shot peening can significantly improve the fatigue resistance of TC4 alloy.
2) In order to improve the wear resistance of TC4 titanium alloy, refractory point coatings, such as tungsten carbide and chromium carbide, can be coated with plasma or explosive spraying on the parts that are easy to wear, such as the side of the damper table of the fan blade. This method can also be used to repair worn parts of titanium alloy parts.
3) In order to avoid scratching and bonding of titanium alloy parts during work, anodizing, chrome plating, electroless nickel plating or nitriding treatment can be carried out on parts with friction contact and thread combination.
Application overview of TC4 titanium alloy
TC4 titanium alloy is a commonly used titanium alloy material, which is composed of elements such as titanium, aluminum, zinc and iron. It has the characteristics of high strength, low density, excellent corrosion resistance and good toughness, so it has a wide range of applications in many fields.
Aerospace: TC4 titanium alloy is widely used in the field of aerospace, for the manufacture of aircraft, missiles, rockets and other components. Its high strength and low density make the aircraft lighter, improve fuel efficiency, and have good corrosion resistance, which can adapt to harsh air environments.
Medical equipment: TC4 titanium alloy is used to make artificial joints, dental restoration materials, implants and other medical equipment. It has good biocompatibility, can reduce the rejection reaction to the human body, and has good corrosion resistance and mechanical properties, which can meet the requirements of medical devices.
Chemical industry: TC4 titanium alloy is widely used in reactors, heat exchangers, storage tanks and other equipment in the chemical industry. Its corrosion resistance can adapt to the erosion of various acids, alkalis and other chemical substances to ensure the safe operation of equipment.
Automobile manufacturing: TC4 titanium alloy is used in engine parts and chassis components in automobile manufacturing. The high strength and low density of titanium alloy can reduce the weight of the car body and improve the performance of the car. At the same time, it has the characteristics of heat resistance and wear resistance, which can meet the requirements of the car under complex working conditions.
Sporting goods: TC4 titanium alloy is widely used in the field of sporting goods, such as golf clubs, bicycle frames, etc. Its high strength and excellent elastic performance can provide better hitting power and shock absorption effect, and at the same time, it has corrosion resistance and is suitable for use in outdoor environments.
In short, due to its excellent performance, TC4 titanium alloy has wide application potential in aerospace, medical equipment, chemical industry, automobile manufacturing, sporting goods and other fields.
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