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Chemical Properties and Processing Technology Analysis of TA18 Titanium Alloy

1、 Chemical composition of TA18 titanium alloy
TA18 titanium alloy is an alpha beta type alloy with excellent comprehensive properties, widely used in aerospace, automotive, shipbuilding and other fields. Its chemical composition affects the strength, ductility, and corrosion resistance of materials. The main element of TA18 is titanium (Ti), and aluminum (Al), vanadium (V), iron (Fe) and other elements are appropriately added. Its typical chemical composition (by mass percentage) is as follows:
Titanium (Ti): Excess
Aluminum (Al): 2.0% -3.0%
Vanadium (V): 2.0% -3.0%
Iron (Fe): ≤ 0.30%
Oxygen (O): ≤ 0.15%
Nitrogen (N): ≤ 0.05%
Hydrogen (H): ≤ 0.015%
Carbon (C): ≤ 0.08%
The proportion of these elements plays an important role in the performance of TA18 titanium alloy. For example, the presence of aluminum increases the strength of the alloy and enhances its antioxidant capacity; The addition of vanadium improves the plasticity and ductility of titanium alloys; And iron helps to further improve the strength of the material.
2、 Chemical Performance Analysis of TA18 Titanium Alloy
TA18 titanium alloy has excellent corrosion resistance, especially exhibiting good corrosion resistance in chloride environments. In the chemical industry and marine fields, titanium alloys are widely used in the manufacture of heat exchangers, chemical equipment, and marine engineering structural components due to their corrosion resistance. Experiments have shown that the corrosion rate of TA18 in a 3.5% NaCl solution is only 0.005mm/year, which is significantly better than stainless steel and other commonly used metal materials.
TA18 titanium alloy exhibits excellent oxidation resistance at high temperatures and can withstand oxidation environments up to 600 ℃. This makes it widely used in high-temperature conditions such as aerospace engines and heat exchangers. The presence of aluminum further enhances the oxidation resistance of the alloy and effectively reduces the thickness of the oxide layer generated in high-temperature environments.
Hydrogen embrittlement resistance is an important issue faced in the use of titanium alloys. Due to its unique chemical composition, TA18 exhibits excellent resistance to hydrogen embrittlement in hydrogen environments. Under a hydrogen pressure of 6 MPa, the ductility of TA18 titanium alloy decreased by less than 10% during testing, significantly better than other α - β - type titanium alloys.
3、 Analysis of Processing Technology for TA18 Titanium Alloy
The heat treatment method of TA18 titanium alloy has a significant impact on its final properties. Usually, a combination of solution treatment and aging treatment is used to improve the strength and toughness of materials. The solution treatment temperature is generally 850 ℃ to 900 ℃, with a holding time of 1 hour, followed by air or water cooling. The temperature for aging treatment is usually set between 500 ℃ and 550 ℃, with a duration of 4 hours.
By reasonable heat treatment, the tensile strength and ductility of TA18 can be significantly improved. For example, after reasonable aging treatment, the tensile strength of TA18 titanium alloy can reach 950 MPa, while the elongation rate remains above 10%, ensuring its application under high strength and high toughness requirements.
The forging process of TA18 titanium alloy has a significant impact on its microstructure and mechanical properties. Due to the high deformation resistance of titanium alloys, the forging temperature needs to be controlled between 950 ℃ and 1050 ℃. Excessive temperature can cause grain coarsening and reduce the overall performance of the material. The deformation speed during forging should be kept within a moderate range to avoid rapid deformation that may cause cracks in the material.
In actual production, the forging of TA18 titanium alloy often adopts a multi pass forging process, which ensures uniform refinement of the microstructure by gradually increasing the deformation amount, thereby improving the comprehensive mechanical properties of the material. Experiments have shown that the impact toughness of TA18 titanium alloy can be improved by about 15% after forging.
The welding process TA18 titanium alloy has good welding performance and can be welded using methods such as TIG welding and electron beam welding. Due to the high reactivity of titanium alloys with oxygen and nitrogen at high temperatures, the purity of the shielding gas must be strictly controlled during the welding process, and pure argon gas is usually used as the shielding gas.
The selection of welding current and speed is crucial in TIG welding process. Excessive welding current can easily cause overheating and reduce the strength of the weld seam area; However, low current may lead to insufficient fusion, affecting the integrity of the joint. The recommended welding current is usually 150-200A, and the welding speed is 15-25 cm/min. After appropriate welding, the welding joint strength of TA18 titanium alloy can reach over 90% of the base metal strength.
4、 Cold working performance of TA18 titanium alloy
TA18 titanium alloy exhibits high deformation resistance and low work hardening tendency during cold working, making it suitable for precision machining through methods such as cold rolling and cold drawing. During the cold rolling process, TA18 has good ductility, and even at 50% deformation, the material still maintains an elongation of about 5%.
Reasonable lubrication and mold design are crucial for improving machining accuracy during cold processing. By optimizing the cold working process parameters, the surface quality and dimensional stability of TA18 titanium alloy can be improved.
5、 Application Fields of TA18 Titanium Alloy
Thanks to its excellent chemical and processability properties, TA18 titanium alloy is widely used in high demand fields such as aerospace structural components, marine engineering equipment, petrochemical pipelines, and medical devices. According to different application requirements, the performance of materials can be further improved by adjusting the heat treatment and processing technology.

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