Discussion and Application of the Production and Processing of Aviation Titanium Alloy Fasteners

Entering the 21st century, aerospace has shown broader development prospects. High-level or ultra-high-level aerospace activities have become more frequent, and their role will go far beyond the field of science and technology itself, and will have an impact on politics, economy, military, and even human social life. Broader and far-reaching impact.

It should be pointed out that the tremendous achievements made in the aerospace industry are inseparable from the development and breakthrough of aerospace material technology, and titanium alloys have an irreplaceable position in the aerospace field due to their high strength and light surface quality.

Titanium alloy fasteners generally require solution aging heat treatment to ensure that they meet the requirements for shear strength of 660MPa and tensile strength of 1100MPa.

Fasteners made of titanium alloys must be inspected in detail. In addition to observing whether there is damage to the appearance, they must also be inspected for mechanical properties and metallurgy. Titanium alloy fasteners have strict material standards, quality, performance standards and requirements. ,

The processing technical conditions of titanium alloy fasteners must comply with the relevant requirements proposed in the AMS4967 standard (wires, annealing, forgings and ring parts, heat-treatable titanium alloy bars). Phase, appearance, defect control, and mechanical properties have clear standard requirements and performance requirements.

1. Problems in the processing of titanium alloy fasteners

Corrosion problem. It is easy to form a certain gap during the installation of titanium alloy fasteners, so that surface paint will flow in between metal air strikes, which makes the fasteners vulnerable to clothing during the production process. In the subsequent use process, the tightness of the connection will be affected. The main reason for the corrosion resistance of titanium alloy materials is that there is a protective oxide film on the surface. This film can effectively protect the titanium alloy inside the material from being oxidized, thereby improving the corrosion resistance of the titanium alloy material.

Problems in turning processing. Titanium alloy materials are difficult to process and have poor thermal conductivity. The heat generated during the machining process will not diffuse through the parts and the machine tool structure, but will be concentrated in the cutting area. There is a strong notch sensitivity, which may cause chipping and deformation; while the blunt blade will generate even higher heat And further reduce the life of the tool. The high temperature generated during the cutting process will also cause the workpiece to continue to harden. This phenomenon will affect the surface integrity of titanium, and may cause the geometric accuracy of the part to be inaccurate, and seriously reduce its fatigue strength. In reasonable machining conditions, the turning process is not difficult. If it is for mass production, continuous cutting, and cutting with a large amount of metal removal, cemented carbide tools are required; and steel tools are required for forming cutting or cutting. Make reasonable adjustments and use cermet knives when necessary.

The precision of machining of titanium alloy fasteners. The precision requirements for machinery will be higher. In mechanical production, because the tools are in a state of working wear during each production process, and are calibrated according to the program, the density of titanium alloy fasteners is higher, and the tools are easily worn during the machining process. In the state, the tool is still processed according to the program, it is easy to cause the precision of the compact part in the processing process to be affected. If the precision of the fastener is not strictly controlled within the error range during the entire processing process, the titanium alloy and other materials cannot be closely connected during the use process, which will have a certain impact on the subsequent use. The precision of titanium alloy fasteners in the machining production process is a major problem that needs to be overcome in the production process. For example, the fastener technology product shown in the figure is a product made in a high-precision production workshop, and the connection performance of this product is better. （To be continued..........)