Effect of Cooling Rates during a Double Stage Solution Treatment on the Massive Phase Formation in Ti-6Al-4V Alloy

Abstract:

The effect of cooling rates during a double stage solution treatment (DSST) on the volume fraction of the massive phase (α_m) in Ti-6Al-4V alloy was successfully confirmed in the present study. The morphology of Ti-6Al-4V alloy depends on the cooling rates during the cooling from the β region. The α_m, which has a transformation characteristic between martensite (α′) and α diffusion, is reported to be a potential method for obtaining a fine lamellar α/β by thermal decomposition. The different fraction of α_m was found after DSST with the first stage was conducted above the β-transus temperature at 1050 °C, followed by second annealing at different temperatures in the α+β region. It was found that the formation of α_m exists in a specific temperature region. A longer period in this region, which was calculated based on different cooling rates during DSST, will increase the fraction of α_m in the specimen. All specimens after DSST contain α_m with the α width of approximately 1μm and white-dot particles, which is predicted to be V-enriched precipitates. The DSST can be a potential method for producing a high fraction of α_m, which can be thermally decomposed into a fine lamellar α/β, introducing a Ti-6Al-4V alloy with superior mechanical properties.

• Periodical: Materials Science Forum (Volume 1000)
• Pages: 398-403
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.1000.398
• Online since: July 2020
• Authors: Ghozali Suprobo, Faris Arief Mawardi, Nokeun Park*, Eung Ryul Baek
• Keywords: Cooling Rate, Massive Phase, Phase Transformation, Titanium Alloy

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