News

Analysis of Chemical Composition and Heat Treatment Properties of TA18 Titanium Alloy

1、 Chemical composition of TA18 titanium alloy
1. Basic components
TA18 titanium alloy is an alpha beta type titanium alloy, mainly composed of titanium (Ti), aluminum (Al), vanadium (V), and iron (Fe). The typical chemical composition is as follows:
Titanium (Ti): matrix component, content between 89% and 90%
Aluminum (Al): 5.5% to 6.5%
Vanadium (V): 3.5% to 4.5%
Iron (Fe): ≤ 0.3%
2. Trace elements
In addition to the main components mentioned above, TA18 titanium alloy also contains small amounts of impurities such as oxygen (O), nitrogen (N), and hydrogen (H). The content of these elements is controlled at a very low level to ensure the mechanical properties and corrosion resistance of the alloy.
Oxygen (O): ≤ 0.15%
Nitrogen (N): ≤ 0.05%
Hydrogen (H): ≤ 0.015%
3. Impurities influence
The effects of oxygen, nitrogen, and hydrogen in trace elements on the properties of alloys are significant. For example, an increase in oxygen content will enhance the strength of the alloy, but at the same time reduce its plasticity; Excessive hydrogen can lead to hydrogen embrittlement, causing the alloy to become brittle.
2、 Heat treatment process of TA18 titanium alloy
1. Solid solution treatment
Solution treatment is a key step in improving the properties of TA18 titanium alloy. It is usually carried out within the temperature range of 900 ℃ to 950 ℃ to fully dissolve the β phase in the alloy. The specific steps are as follows:
Heating: Slowly heat the alloy to 930 ℃ and hold for 30 minutes to 1 hour.
Quick cooling: Rapid water or air cooling, this step helps maintain the uniform microstructure of the alloy.
This processing method can improve the strength of the alloy while maintaining good plasticity and toughness.
2. Timeliness processing
Aging treatment is used to stabilize and strengthen the microstructure of alloys. Generally, it is carried out within the temperature range of 500 ℃ to 600 ℃, and the time is controlled within 6 to 8 hours. Specific process:
Heating: Heat the solution treated alloy to 550 ℃ and maintain for 6 hours.
Cooling: Slowly cool to room temperature to stabilize the tissue structure.
Aging treatment enables the alloy to achieve excellent creep resistance and high fatigue strength.
3. Quenching treatment
When TA18 titanium alloy is quenched, water quenching or oil quenching is usually used to improve the hardness and wear resistance of the alloy. The standard steps include:
Preheating: Preheat to 800 ℃ to 850 ℃ to reduce temperature gradients.
Quenching: Quickly quench the preheated alloy into a cooling medium at 20 ℃ to 30 ℃.
Through quenching treatment, the β phase in the alloy transforms into more stable α and β phases at high temperatures, thereby improving hardness and strength.
3、 Performance characteristics of TA18 titanium alloy
1. Mechanical properties
After appropriate heat treatment, TA18 titanium alloy exhibits the following mechanical properties:
Tensile strength: 900 MPa to 1100 MPa
Yield strength: 830 MPa to 950 MPa
Elongation rate: ≥ 8%
Sectional shrinkage rate: ≥ 25%
These characteristics make TA18 titanium alloy widely used in applications that require high strength and toughness.
2. Corrosion resistance performance
The corrosion resistance of TA18 titanium alloy is mainly attributed to the oxide film in the titanium matrix, which has high chemical stability in various environments. Especially in seawater and industrial atmospheres, TA18 exhibits excellent corrosion resistance and is commonly used in marine engineering and chemical equipment.
3. Thermal stability
TA18 titanium alloy can maintain good mechanical properties at high temperatures, which makes it particularly important in the aerospace industry. Its high temperature oxidation resistance enables the alloy to maintain good structural stability and strength even at temperatures up to 500 ℃.
Factors affecting heat treatment
4. Temperature control
Temperature control is a key factor in the heat treatment process. The temperature and time of solution treatment and aging treatment need to be strictly controlled to avoid grain growth and performance degradation. The typical temperature error is controlled within ± 5 ℃ to ensure the consistency of alloy properties.
4. Cooling rate
The cooling rate directly affects the phase transformation and final microstructure of the alloy. The different cooling rates of water cooling and air cooling can lead to different microstructures, thereby affecting the mechanical properties of the alloy. It is usually recommended to avoid internal stress concentration during rapid cooling.
5. Alloy thickness
The thickness of TA18 titanium alloy has a significant impact on the heat treatment effect. Thicker workpieces may require longer insulation time and slower cooling rate to ensure uniform internal structure. Workpieces with typical thicknesses between 5mm and 50mm can achieve uniform microstructure and properties under standard heat treatment processes.

[ 上一页 ] Heat treatment pro...[ 下一页 ] Analysis of Chemic...