Effect of Forging Temperature on Microstructure Evolution and Tensile Properties of Ti-17 Alloys

In this study, the microstructure, tensile strength, elongation, and reduction of area of near-beta Ti alloys (Ti-17) were investigated after being subjected to solution and aging treatments. Ti-17 was forged at temperatures between 700 and 850 degrees C followed by air cooling. Then, the forged Ti-17 was subjected to solution treatment at 800 degrees C for 4 h followed by water quenching and aging treatment at 620 degrees C for 8 h followed by air cooling. Tensile tests were performed at room temperature, 450 degrees C, and 600 degrees C. The change in microstructure at different forging temperatures was exhibited by only the volume fraction and morphology of the grain boundary (GB) alpha phase. That is, a granular GB alpha phase was formed in the samples forged at 700 and 750 degrees C. Moreover, a film-like GB alpha phase was formed in the samples forged at 800 and 850 degrees C. The tensile strength was the same for all the tested samples, indicating that the microstructure has little effect on the tensile strength. The elongation and reduction of area increased with decreasing volume fraction in the GB alpha phase. It is considered that the film-like morphology slightly improves ductility.