In the thermal processing of titanium alloys, the heating temperature is very important. When the temperature is lower, the deformation resistance is greater, and defects such as cracks are easy to occur. At the same time, the deformation speed is also greatly dependent during the hot working process. During the titanium alloy precision hot die processing, the temperature of the forging die is heated to the same level as the forging. It is equal to or higher, which can suppress the temperature drop of the forging during forging.
1. Forging technology of engine discs
Forging technology of engine discs. Discs for aircraft engines require high fatigue strength and fracture toughness. Ti-6Al-2Sn-4Zr-6Mo alloy plated parts are used in the 700K medium temperature area. The traditional processing method is forging in the α-β zone. The structure is β phase, equiaxed α grains and fine needle-like α two-phase structure, and the fracture toughness value is low. To improve this point, a beta forging method with heating in the beta zone was developed.
The beta forging method is heating forging above the beta phase transition temperature, which will produce recrystallization, so the forging temperature and processing deformation have a great influence on the material properties, and it is not allowed to reheat during forging to stop deformation. Therefore, the forging temperature and the amount of deformation must be strictly controlled in β forging. For Ti-6Al-2Sn-4Zr-Mo alloy, the processing temperature is in the range of 1073~1323K, and there must be sufficient processing deformation, the forging structure is all needle-shaped, and the fracture toughness value is improved.
2. Turbine blade forging technology
Turbine blades are very thin, and the temperature drops quickly during the forging process. Therefore, the die needs to be accurately designed. A process for effectively using the upper and lower blow energy to form the blade surface is currently being developed. Plane forging is performed, then bend forming, and then precision forging.
3. Ring manufacturing technology
The engine fan housing and compressor housing all use Ti-6Al-4V alloy rolling process. For titanium alloy products with relatively high material costs, reducing the amount of material input is very effective in reducing costs. Generally, near-net technology (yes Means that after the parts are formed, they can be used as a forming technology for mechanical components with only a small amount of processing or no longer processing). Using this technology, the amount of material will be reduced by more than 55%.
When processing thick rings, in order to avoid cracks, it is necessary to give as much pressure as possible, and attention should be paid to the control of the structure and the temperature drop of the ring during processing. In short, the production of titanium alloy forgings requires proper processing temperature and proper deformation to obtain high-quality forgings.
For this reason, it is necessary to give full play to the characteristics of titanium alloys in the manufacturing process of titanium forgings. In order to obtain high-quality forgings, the forging temperature and plastic deformation must be properly controlled during production.