Superplastic Forming and Superplastic Forming and Diffusion Bonding of Fine Grain Titanium 6Al-4V for Producing Aerospace Hardware

In the past, if you wanted a fine grain alpha-beta titanium material capable of Superplastic Forming (SPF) at temperatures lower than about 900°C, you were limited to the SP700 alloy that had been developed by NKK Corporation, now JFE Steel Corporation, in Japan.  The most widely used standard grain titanium alloy is 6Al-4V, which has a grain size of about 8 µm, and this material is typically formed at around 900°C.  Verknaya Salda Metallurgical Production Association (VSMPO) in Russia has developed a fine grain version of the 6Al-4V alloy, with a grain size of about 1 µm, which is able to be superplastically formed at around 775°C.   Since this material diffusion bonds to itself as well as standard grain size alpha-beta titanium alloys at this temperature, Superplastically Formed and Diffusion Bonded (SPF/DB) hardware can be produced.  There are several advantages to using this lower forming temperature including a smaller amount of alpha case is developed on parts so there is less to remove, longer press platen and heater life, and less oxidation of the tool surface.  In order to take advantage of these improvements, this material is currently being used in the production of SPF and SPF/DB aerospace components.