Properties and Microstructure of Forged Powder Metallurgy Ti6Al4V Alloy

The powder metallurgy (PM) Ti6Al4V alloy was forged in different ways. The properties and microstructure of the alloy before and after forging were analyzed. The results show that forging is an effective way to improve the density and mechanical properties of PM titanium alloys. Firstly, once forging deformation at different temperatures was performed for the PM Ti6Al4V alloy. The alloy forged at 960 degrees C has better ductility with an elongation of 15.44%. With the increasing of forging temperature, the equiaxial a phase decreases, and gradually changes to the basket weave structure, resulting in the plasticity decreasing. However, due to the inhibition of the original powder particle boundary against grain growth, there is no obvious grain growth in the alloy forged at 1150 degrees C. The grain smaller than 20 gm amounts to about 79%. As fine grain size is beneficial to the plasticity, the elongation still reaches to 14.30%. Therefore, the PM Ti6Al4V alloy has a wider forging temperature window compared to the traditional cast titanium alloy. Besides, twice forging deformation at different temperatures was performed for the PM Ti6Al4V alloy. In such case, the alloy was firstly forged at high temperature to improve the density with small deformation, and then was forged at lower temperature to obtain the required microstructure. The Ti6Al4V alloy with twice forging deformation has an elongation higher than 17%, tensile strength higher than 994 MPa, and yield strength higher than 960 MPa.