Overview of composition design and development of TC4 titanium alloy

Update: 10-10-2020

The composition of the alloy fundamentally determines t […]

The composition of the alloy fundamentally determines the performance of the alloy. With the increasing requirements for material performance and changes in material design concepts, people have carried out different levels of composition optimization and redesign for TC4 alloy in order to meet different needs.
There are many optimization and redesigns for the composition of TC4, such as the early TImetaL 62S (Ti-6Al-2Fe-0.1Si), Ti8LC (Ti-Al-Fe-Mo), Ti12LC (Ti-Al-Fe-Mo) and so on. In recent years, TImetaL CL4 (Ti-5Al-3V-0.6Fe-0.1O), ATI 425 (Ti-4Al-2.5V-1. 5Fe-0.25O), Ti575 (Ti-5.3Al-7.7) have also been developed in succession. V-0.5Si), Ti-54M (Ti-5Al-4V-0.75Mo-0.5Fe), Ti407(Ti-0.85Al-3.7V-0.25Fe-0.25Si) and a series of TC4 modified titanium alloys.
There are two main purposes for TC4 modification. One is for performance considerations, especially its dynamic mechanical properties. For example, Ti575 alloy, compared with TC4, the alloy has reduced Al equivalent, increased Mo equivalent, and added a small amount of Si to improve the strength of the alloy. Its tensile strength and yield strength are both higher than TC4, and when the tensile strength is 1200 MPa, the elongation can reach 10.5%, which is 8% higher than the strength of TC4. And compared to TC4 alloy, this alloy has better fatigue properties and forgeability.
Another purpose of the TC4 modification is to reduce costs. TImetaL CL4 and ATI 425 both reduce the content of Al and V on the basis of TC4 and add a certain amount of Fe and O elements. While ensuring the strength, it improves the cold workability of the TC4 alloy, thereby reducing the cost. Ti407 alloy has a lower Al equivalent and improves its processing performance by sacrificing the strength of the material. The design purpose of this alloy is mainly to partially replace TC4 and reduce the cost of commercial aircraft materials. Compared with TC4, Ti-54M contains a lower Al equivalent, and a small amount of Mo and Fe elements are added to lower the β transformation temperature. Compared with TC4, this alloy has better processability and formability, and its superplastic forming ability is better than that of TC4 material, which can significantly reduce processing costs.