Ti 6 Al- 4 V is hardened by heat treating by preforming a solution
anneal at 1750F- 1775F for 1 hr followed by water quench followed by
an aging heat treatment at 900F-1100F for 4-8 hours. After heat
treating you will need to remove a few thousandths (.002"-.004") of
oxidized alpha phase titanium or you will be likely to see some
cracking of the material if you stress it as the oxidized case is
very brittle and hard. The only real way to remove it is chemical
etching as this case is harder than most cutting tools including
carbide. For that you need to use HF or Multi Etch. I would highly
advise the use of Multi Etch but even then significant caution is
advised, read and understand the MSDS.
James Binnion
James Binnion Metal Arts