Dense layer, microstructure, and mechanical performances of Ti-6Al-4V alloy prepared by metal injection molding

One of the most recent methods for fabricating titanium-based products is metal injection molding (MIM). However, there have been few systematic studies on the definition and generation mechanism of surface porosity of MIM Ti-6Al-4V and its relationship with powder, process, and mechanical performances so far. In this article, MIM was selected to produce Ti-6Al-4V, and the investigation aimed to determine the impact of the sintering and subsequent hot isostatic pressing (HIP) process on its microstructure and mechanical performances. The results indicate that Ti-6Al-4V alloy formed a dense layer after sintering because of the temperature gradient from surface to core. The thickness of dense layer, grain size, grain morphology, and grain orientation are the key factors that determine Ti-6Al-4V alloy's mechanical performances. Under the condition of sintering at 1000 celcius with HIP process, Ti-6Al-4V alloy formed a dense layer with a thickness of 290 mu m, equiaxed grains with an average grain size of 16 mu m, and a significant number of high-angle grain boundaries (88.9%). The optimized microstructure of Ti-6Al-4V led to outstanding mechanical performances, exhibiting tensile strength of 1067 MPa, yield strength of 997 MPa, and elongation of 17.5%. Other MIM materials can also be guided by this approach.

Automated summary

This article investigates the impact of the sintering and hot isostatic pressing process on the microstructure and mechanical performances of Ti-6Al-4V alloy manufactured by MIM. The results indicate that the thickness of the dense layer, grain size, grain morphology, and grain orientation are key factors determining the mechanical performances. Under the optimized condition, Ti-6Al-4V alloy exhibits outstanding mechanical performances with high tensile strength, yield strength, and elongation.