Calculating Ti-6Al-4V beta transus through a chemistry based equation derived from combined element phase diagrams

A mathematical model was developed to correlate the relationship between titanium alloying elements (Al, O, N, C, V, and Fe) in Ti-6Al-4V, and the resulting beta transus temperature (βt). The model was produced by analyzing the slope of the alpha+beta (α+β) and beta (β) line on combined element binary phase diagrams generated through the PANDAT modeling software. Experimental results showed a strong agreement between the baseline data, obtained through differential thermal analysis (DTA), and the calculated βt, determined by measuring the chemistry at a location adjacent to the DTA sample. The difference between the calculated βt and the baseline DTA data was approximately +/-10°F. The thermodynamically ideal βt temperature was additionally modeled for each set of chemistries through PANDAT. These results were compared against the βt temperatures determined through the equation and DTA methods.