[TheForge] Heat treat for Titanium

Tue Sep 5 15:30:36 EDT 2006

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.

Michael wrote:
> Hi Dave; welcome back.
> I'm afraid you are about to be contradicted. Titanium is infamous for
> hydrogen embrittlement at elevated temperatures, unless it is heat treated
> either in solution or within a special inert gas filled furnace. Hydrogen
> embrittlement is one of the reasons Titanium is so tricky to weld (argon or
> helium purge on the backside for TIG work. Electroplating recommended before
> soldering or brazing if the part is structural.
> Mikey
> 
> -----Original Message-----
> From: theforge-bounces at mailman.qth.net
> [mailto:theforge-bounces at mailman.qth.net] On Behalf Of David E. Smucker
> Sent: Monday, September 04, 2006 1:49 PM
> To: Sponsored by ABANA
> Subject: Re: [TheForge] Heat treat for Titanium
> 
> Titanium alloys are solution heat treated just as aerospace aluminum alloys 
> are solution heat treated.  Since almost all Titanium you will come across 
> was intended for aerospace or medical applications most titanium alloys can 
> be and are solution heat treated. (Some of the medical ones may not be.)
> 
> I have never myself heat treated titanium alloys so what follows is 
> "handbook" information.  I have been around tons of aluminum aerospace heat 
> treating.
> 
> First I assume that you have no clue to what alloy content your titanium 
> happens to have -- so what follow is rather general.  There are a whole 
> range of titanium alloys from alpha, to alpha-beta, to beta alloys.  These 
> types deal with the alloy contend and the type of structures these alloys 
> have at various temperatures.
> 
> Those titanium alloys that are solution heat treatable are generally heated 
> to 1700 to 1800 F and then water quenched.  They are then followed by a 
> aging at temperature in the range of 1000 F for 4 to 8 hours.  What happen 
> in solution heat treating is the alloying elements go into solution at the 
> heat treating temperature and are then kept in solution by quenching.  The 
> aging at the elevated temperature completes the cycle giving the high 
> strength and hardness you might be looking for.
> 
> This said, if solution heat treating of titanium is anything like the 
> solution heat treating of aluminum then very bad things happen if you over 
> heat  (for aluminum airplanes fall out of the sky).  What happens is that 
> you get local melting of the alloy and this results in soft or weak spots in
> 
> the product.
> 
> But since you are making a sticker, and it is unlikely that if they "fail" 
> they will kill someone, give it a try.
> 
> Heat your item to 1700 F, this is what I would call an orange heat.  Then 
> quench, then reheat to a dull red in very low light.  Let air cool.
> 
> Dave Smucker
> (Hey, I been gone a long time.)
> 
> 
> ----- Original Message ----- 
> From: "Bruce Freeman" <freemab222 at yahoo.com>
> To: "Bob Ehrenberger" <eforge at centurytel.net>; "Sponsored by ABANA" 
> <theforge at mailman.qth.net>
> Sent: Monday, September 04, 2006 12:48 AM
> Subject: Re: [TheForge] Heat treat for Titanium
> 
> 
>> Well...I'm no expert on titanium, but I wouldn't think
>> that heat treating would have any bearing on the
>> matter.  Steel is kinda unique, in that it is an
>> iron-carbon alloy.  It is because of the properties of
>> the various iron-carbon species that hardening and
>> tempering work the way they do.
>>
>> For example, you anneal steel by heating it to red
>> (above critical) an cooling REAL slowly, and you
>> harden it by heating it likewise and quenching it in
>> water.  In contrast, most metals are annealed by
>> bringing them up to a red heat (or at least till soft
>> - as red heat melts aluminum, for example) and
>> quenching in water.
>>
>> So, I don't know what the procedure would be for
>> titanium, if indeed there is any, to harden it.  Seems
>> to me it's just "nacherly" hard.
>>
>> You might try work-hardening it.  That works on most
>> metals.
>>
>> Bruce
>> OR/NJ
>>
>>
>> --- Bob Ehrenberger <eforge at centurytel.net> wrote:
>>
>>> A while back Pat McCarty brought a flint striker
>>> made form titanium to a BAM
>>> meeting.  It was real impressive  and put out a
>>> shower of white sparks.
>>> Well I got a piece of titanium and made a striker
>>> this last week. Not
>>> knowing how to heat treat it I just normalized it.
>>> Something isn't right,
>>> I get an occational white spark but only about one
>>> out of every 6-10 hits.
>>>
>>> I called Pat and he couldn't remember what he did to
>>> get the nice sparks.
>>>
>>> Does anyone have any idea on how to heat treat it to
>>> get good sparks.  I
>>> thought I'd ask before I experimented and runed it.
>>>
>>> Robert Ehrenberger
>>> Shelbyville, Mo.
>>> eforge at centurytel.net
>>>
>>>
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-- 
                 Cameron Stoker
                 cameron at stoker.net
                 "May you run like a vicuña!"