Microstructure Evolution and Strength Mechanism of Metastable Powder Metallurgy Ti-6554 Titanium Alloys Under Different Heat Treatment Conditions

The effects of solution-aging treatment on microstructure and mechanical properties of powder metallurgy (PM) Ti-6554 titanium alloy were investigated. PM Ti-6554 titanium alloy can achieve a good balance between strength and ductility after solution treatment at 810 degrees C/30 min with furnace cooling and aging treatment at 520 degrees C/6 h. Accordingly, the ultimate tensile strength, yield strength and elongation were 1360 MPa, 1323 MPa and 9.0%, respectively. The alloy had smaller alpha phase grain size (similar to 0.69 mu m), and its volume fraction was 73%. When the solution temperature increased from 810 degrees C to 850 degrees C, the ultimate tensile strength increased to 1601 MPa, the yield strength increased to 1543 MPa, and the elongation reduced to 3.5%. Microstructure results showed that the grain size of alpha phase gradually increased, while the volume fraction of alpha phase showed the opposite trend. When the solution temperature remained constant, slower cooling rate was beneficial to increase the alloy strength and maintain the strength-plasticity matching.

Automated summary

The effects of solution-aging treatment on the microstructure and mechanical properties of PM Ti-6554 titanium alloy were investigated. The alloy showed a good balance between strength and ductility after solution treatment at 810 degrees C/30 min with furnace cooling and aging treatment at 520 degrees C/6 h. Increasing the solution temperature from 810 degrees C to 850 degrees C resulted in increased ultimate tensile strength and yield strength, but reduced elongation. The microstructure analysis revealed that the grain size of the alpha phase increased with solution temperature, while the volume fraction showed an opposite trend. Slower cooling rate during solution treatment was beneficial for maintaining the strength-plasticity matching.