In order to solve this difficulty, scientific and technological personnel have developed a superplastic titanium alloy, which is heated between 6 80℃ and 79 0℃, the molding pressure is 1.4 mpa to 2.10 mpa, and the processing time is within 8 minutes. If the ordinary forging method is used, the blank of 158.8 kg needs to be forged, and then the shape is made by mechanical processing. When 500 aircraft are produced, this part alone can save $1.2 million to $1.5 million. Another example is the use of titanium alloy superplastic molding process to manufacture B-1 jet aircraft door, tail cabin, skeleton, the original process requires 100 parts, through a variety of methods connected and assembled. If the superplastic alloy is used, it can be made in one molding, so that the weight of the tail cabin is reduced by 3% and the cost is reduced by 55%.
The superplastic forming technology of titanium alloy is a new technology developed by using the excellent deformation properties of the material in the superplastic state. Titanium alloys have superplasticity, among which Ti-6Al-4V is considered to be a structural titanium alloy with good application prospects because of its excellent superplastic properties. Rapid development and good economic benefits have been achieved in the research and application of structural titanium alloy superplastic forming process. Compared with other titan-based alloys, Ti-6Al-4V is widely used and mature in superplasticity.
TC4 is a very widely used titanium alloy with good superplastic properties, so it is of practical significance to study the mechanical properties of this material after superplastic forming. The ductility of titanium alloy Ti-6Al-4V is relatively low at room temperature, but it has high ductility at high temperatures. High-temperature oxidation is a major factor affecting the superplasticity of Ti-6Al-4V. Although the oxidation resistance of Ti-6Al-4V is good, the high-temperature oxidation on the surface of titanium alloy Ti-6Al-4V forms an oxide film when the temperature is between 800℃ and 900℃, which will cause cracks and thus reduce the ductility of titanium alloy. In order to prevent the oxidation of titanium alloys during high temperature forming, in many cases, it is carried out under Ar protection. Although this method can protect titanium alloys from oxidation during the superplastic process, it requires complex equipment and greatly increases the process cost.