Titanium alloy Forging and cooling process after forging
Titanium alloy forging process: perfect transformation from billet to two-phase alloy
Titanium alloy forging process. As a lightweight, high-strength, and excellent corrosion-resistant material, titanium alloy has a wide range of applications in aviation, medical, chemical, and other fields. The forging process is a key link in the processing of titanium alloys, and its quality directly affects the performance of the final product.
1、 The titanium alloy billet must be carefully prepared before forging. The surface of the billet should be roughly machined or ground to ensure a smooth surface without obvious defects and impurities. Rod materials are usually processed through turning or center grinding. When cutting the billet, it is recommended to use a band saw to avoid the heat affected zone and oxidation that may occur during gas cutting.
2、 During the heating process, the first step is to remove the slag and oxide scale from the furnace bottom to ensure a clean environment inside the furnace. When heating titanium alloys, an oxidizing atmosphere should be used to slow down the saturation process of hydrogen and reduce the oxidation and gas pollution of titanium alloys. Meanwhile, it is necessary to strictly control the heating temperature and time to minimize grain growth. The mold should also be preheated to 250-350 ℃ in advance and kept warm for more than 12 hours to reduce the temperature difference between the mold and the titanium alloy.
3、 The forging deformation of titanium alloy is generally controlled between 40% and 80%. After the last heating, the entire metal should have uniform deformation, and the temperature distribution during the deformation process should be uniform to prevent cracking caused by deformation at too low a temperature. For two-phase titanium alloys, sufficient deformation is particularly important because grain refinement cannot be achieved through heat treatment methods, but can only be achieved through deformation.
4、 The design of titanium alloy forging molds is different from that of steel forging molds. The shrinkage rate of titanium alloy forging molds is relatively small, usually with a ratio of 1:1.87 to that of steel forging molds. When using equally deep and complex molds, the mold for forging titanium alloy is 50% thicker than the mold for forging steel. In addition, the fillet radius of the mold should be large, and the surface smoothness of the mold chamber is required to be high.
5、 The forging of two-phase titanium alloys in the full phase region can improve the forging performance of titanium alloys at high temperatures or enhance the notch toughness of forgings. In order to obtain forgings with high comprehensive performance, the microstructure of the forged alloy should be controlled within a certain range. The content of this phase should be controlled between 15% -30%. Excessive content can lead to a decrease in notch toughness, while insufficient content can result in a decrease in elongation. If the phase content in the forging is too high, its properties can be restored through heat treatment.
In summary, the titanium alloy forging process is a complex and intricate process that involves