[TheForge] Heat treat for Titanium

[Bob Ehrenberger]

Cameron,

The chances of me setting up a pot of hot borax is just about 0.  I get
enough burns from scale and borax when doing regular work.  Hot borax
forging would be almost a death wish.

I was wondering about surface scale (oxide) interfering with the flint.  I
may try grinding the surface to get down to clean metal.

I did try heating to orange and quenching today, no apparent difference.

I then heated to dull red and let air cool, still no difference.

I guess tomorrow I'll grind the surface and see if that helps.  So far the
only thing that has helped is using a better flint and hitting it real hard.

Robert Ehrenberger
Shelbyville, Mo.
eforge at centurytel.net


----- Original Message ----- 

Date: Tue, 05 Sep 2006 13:30:36 -0600
From: Cameron Stoker <cameron at stoker.net>
Subject: Re: [TheForge] Heat treat for Titanium

Here's my little bit of Ti related info:

I think the most common forms of Ti encountered are either cp
(chemically pure) or 6al4v (6% aluminium, 4% vanadium). The cp won't
harden at all. The fancier stuff will solution harden as described, but
unlike steel the hardening process doesn't increase it's hardness
properties by an order of magnitude, it's more like a 30% gain. So all
the work of holding at temp. in a controlled atmosphere probably won't
make much difference in it's behavior with the flint.
The blacksmitherly approach to keeping hydrogen & oxygen away from the
surface is to drown the thing in molten borax.  I recall that it starts
reacting with the atmosphere anywhere above 700*f. You make up a pot and
fill it with borax to get it nice and melty, then dip you piece after a
little pre heat. Keep it covered all the time it's above 700*f. Be
carefull, it's really slippery. And I'd guess a piece as small as a
striker would only permit a few blows before it lost it's heat. When you
quench it, some of the borax may pop off, but most of it will be there
for a long time. Usually easiest to just grind it all off.
The borax coating keeps the elephant-skin like texture from forming.
This oxide layer is amazingly hard and cracks in it's surface will start
stress risers in the parent metal. I'd also bet that the oxide is strong
enough to keep the flint from scraping any base metal slivers off.