Analysis Of Processing Technology Of Titanium Alloy Structural Parts

Since its rise in the 1950s, titanium and its alloys have stood out among many metal structural materials due to their unique performance advantages. It has significant advantages such as high specific strength, good medium temperature performance and corrosion resistance, which makes titanium alloy one of the main structural materials in key fields such as contemporary advanced aircraft and engines. However, the initial cost of titanium products is relatively high. In order to ensure its performance while minimizing processing costs, it is particularly important to carefully select the processing route and develop a suitable titanium alloy processing technology. Among the many processing processes, the titanium aluminum alloy water jet cutting (AWJ) process has gradually attracted attention for its unique advantages.

1. Challenges And Needs Of Titanium Alloy Processing

Although titanium alloys have excellent performance, they face many challenges in the processing process. Its high strength and low thermal conductivity make the tool wear serious during processing and the processing efficiency is low. At the same time, titanium alloy can easily react with oxygen and nitrogen in the air at high temperatures, forming a hard and brittle oxide layer on the surface of the workpiece, which affects the processing quality and the performance of the workpiece. In addition, the elastic modulus of titanium alloy is low, and it is prone to elastic deformation during processing, making it difficult to guarantee the machining accuracy.

Based on these challenges, titanium alloy processing technology needs to meet the following needs: first, to reduce the mechanical and thermal damage to the surface of the workpiece during processing and ensure the surface quality of the workpiece; second, to improve the machining accuracy and ensure that the geometry of the workpiece meets the design requirements; third, to improve processing efficiency, reduce processing costs, and improve economic benefits.

2. Principles And Advantages Of AWJ Process

The AWJ process is a processing method that uses a high-pressure water jet to carry abrasives to cut materials. During the processing process, a high-pressure water pump pressurizes the water to extremely high pressure, and then jets the water jet out at an extremely high speed through the nozzle, while adding abrasives (such as garnet, silica sand, etc.) to the water jet. Under the acceleration of the water jet, the abrasive strikes the surface of the workpiece with extremely high kinetic energy to achieve the cutting of the material.

The AWJ process has significant advantages in titanium alloy processing. First of all, since a large amount of heat is not generated during the water jet cutting process, the mechanical and thermal damage to the surface of the workpiece is small, which can effectively ensure the surface quality of the workpiece. This is particularly important for heat-sensitive materials such as titanium alloys, which can avoid the performance degradation of the workpiece caused by heat. Secondly, the cutting force of the AWJ process is evenly distributed, which can reduce vibration and deformation during processing and improve machining accuracy. In addition, the AWJ process can also process various complex shapes of workpieces, which has high flexibility.

3. Factors Affecting The Processing Quality of AWJ Process

1) Geometric Accuracy (Straightness Of Cutting Joints)

The straightness of the cutting seam is one of the important indicators to measure the processing quality of the AWJ process. Operating parameters such as pump pressure, material movement speed, abrasive flow speed, and projection distance will all have an impact on the straightness of the seam. If the pump pressure is too high or too low, the cutting seam may not be straight. If the pressure is too high, the water jet will diverge, and if the pressure is too low, it will not be able to provide sufficient cutting energy. The material moves too fast, and the water jet is too late to fully cut the material, which will cause the cutting seam to bend; if the speed is too slow, it will increase the processing time and reduce the processing efficiency. The abrasive flow speed and projection distance will also affect the stability of the cutting and the straightness of the cutting seam. The appropriate combination of parameters can ensure that the straightness of the cutting seam meets the requirements.

2) Uniformity Of Surface Roughness

The uniformity of surface roughness reflects the smoothness of the workpiece surface and the formation of stripes. In the AWJ process, stripe forming can be studied by measuring the surface roughness of the cutting surface along the cutting direction. Factors such as pump pressure, material movement speed, and abrasive particle size affect the uniformity of surface roughness. Fluctuations in pump pressure can cause instability of cutting energy, resulting in uneven surface roughness. Changes in the speed of material movement will also affect the frequency and strength of abrasive impact on the surface of the workpiece, which in turn affects the surface roughness. The size of the abrasive particle size will also have an impact on the surface roughness. If the particle size is too large or too small, the surface roughness may be uneven.

3) Workpiece Surface Integrity

The surface integrity of the workpiece includes issues such as sand grain embedding after cutting and possible recasting micro-layers or material drawing/micro-cracks after cutting. During the cutting process, abrasive particles may be embedded on the surface of the workpiece, affecting the surface quality and performance of the workpiece. In addition, the impact of the high-pressure water jet may cause the surface of the workpiece to recast the microscopic layer and change the organizational structure of the material. At the same time, the stress concentration during the cutting process may also cause the material to be drawn or microcracks may occur, reducing the strength and reliability of the workpiece. Factors such as pump pressure, material movement speed, and abrasive type all affect the surface integrity of the workpiece. Higher pump pressure and excessive material movement speed may increase the risk of sand embedding and microcracks, and different types of abrasives have different effects on the surface of the workpiece.

4. Strategies To Optimize The AWJ Process

In order to improve the quality of titanium alloy structural parts processed by the AWJ process, it is necessary to optimize the above influencing factors. First of all, a large number of experimental studies must be carried out to determine the best combination of operating parameters of titanium alloys of different thicknesses and materials under the AWJ process. By adjusting the parameters of pump pressure, material movement speed, abrasive flow speed and projection distance, the best process conditions can be found to ensure geometric accuracy, surface roughness uniformity and workpiece surface integrity.

Secondly, choose the right abrasive. Factors such as the hardness, particle size and shape of the abrasive will affect the cutting effect and the surface quality of the workpiece. For titanium alloy processing, abrasives with moderate hardness, uniform particle size and regular shape should be selected to reduce sand embedding and the generation of microcracks.

In addition, auxiliary measures can be used to improve the processing quality. For example, the use of coolant in the cutting process can reduce the temperature of the cutting area and reduce the thermal impact; the use of suitable fixtures can fix the workpiece and reduce vibration and deformation during processing.

The processing of titanium alloy structural parts is a challenging task, and the AWJ process provides an effective solution for titanium alloy processing. Through in-depth research on the principle and influencing factors of the AWJ process, and adopting corresponding optimization strategies, the processing quality of titanium alloy structural parts can be improved, processing costs can be reduced, and the high-performance requirements of titanium alloy structural parts in aerospace and other fields can be met. In the future, with the continuous development and innovation of technology, the application prospects of AWJ technology in the field of titanium alloy processing will be broader.