Microstructural adjustment of hot-rolled Ti-6Al-4V based on a CCT diagram

The effects of post-processing heat treatments on hot-rolled Ti-6Al-4V with extra low interstitial concentration were investigated. The 2 mm sheets were rolled in the single beta phase field region and subsequently cooled in air. A continuous cooling transformation (CCT) diagram was generated, revealing the strong influence of the cooling rate on both microstructure and hardness. Cooling rates between 0.01 and 200 degrees C s(-1) were selected. While rapid cooling resulted in a martensitic transformation beta -> alpha', decrease in the cooling rate led to a progressive spheroidization of the lamellar (alpha + beta) microstructure. With a focus on the established CCT continuous cooling transformation diagram, this study contains insight on the microstructure evolution of the Ti-6Al-4V ELI alloy during cooling from the single beta phase field region.