Overview of the Component Design and Development of TC4 Titanium Alloy

The composition of the alloy fundamentally determines its performance. With the increasing demands for material properties nowadays and the changes in material design concepts, people have carried out various degrees of composition optimization and redesign for TC4 alloy in an attempt to meet different requirements.

There are numerous component optimization and redesigns for TC4, such as the earlier TImetaL 62S (Ti-6Al-2Fe-0.1Si), Ti8LC (Ti-Al-Fe-Mo), and Ti12LC (Ti-Al-Fe-Mo), etc. In recent years, a series of TC4 modified titanium alloys have also been developed, including TImetaL CL4 (Ti-5Al-3V-0.6Fe-0.1O), ATI 425 (Ti-4Al-2.5V-1.5Fe-0.25O), Ti575 (Ti-5.3Al-7.7V-0.5Si), Ti-54M (Ti-5Al-4V-0.75Mo-0.5Fe), and Ti407 (Ti-0.85Al-3.7V-0.25Fe-0.25Si). The main purposes for the TC4 modification are two. One is for performance considerations, especially its dynamic mechanical properties. For example, the Ti575 alloy, compared to TC4, has reduced the Al content, increased the Mo content, and added a small amount of Si to enhance the alloy's strength. Its tensile strength and yield strength are both higher than those of TC4, and at a tensile strength of 1200 MPa, the elongation can reach 10.5%, which is 8% higher than the strength ratio of TC4. Moreover, compared to the TC4 alloy, this alloy has better fatigue performance and forgeability.

Another purpose of the TC4 modification is to reduce costs. TImetaL CL4, ATI 425 all reduce the content of Al and V on the basis of TC4 and add a certain amount of Fe and O elements. While maintaining the strength, they improve the cold workability of the TC4 alloy, thereby reducing costs. The Ti407 alloy has a lower Al equivalent. By sacrificing the material's strength to improve its processing performance, the main design purpose of this alloy is to partially replace TC4 and reduce the cost of commercial aircraft materials. Compared with TC4, Ti-54M has a lower Al equivalent and contains a small amount of Mo and Fe elements to lower the β transformation temperature. Compared with TC4, this alloy has better processing and forming properties, and its superplastic forming ability is superior to TC4 materials, which can significantly reduce processing costs.