[TheForge] Heat treat for Titanium

[schade at acegroup.cc]

On Sep 5, 2006, at 3:31 PM, schade at acegroup.cc wrote:

>
> On Sep 5, 2006, at 2:30 PM, Cameron Stoker wrote:
>
>> Here's my little bit of Ti related info:
>>
>> I think the most common forms of Ti encountered are either cp 
>> (chemically pure)
>
>> The blacksmitherly approach to keeping hydrogen & oxygen away from 
>> the surface is to drown the thing in molten borax.
>
>>  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.
>>
>
>
>
>
>
>
> seems like a lot of bother. I have forged small amounts
> of 3/4" round titainium. I never had a problem with "elephant skin".
> Also I think the "cp" means "commercially pure" but I really don't
> know what that means.
>
> Bob
> _______________________

I did a search after writing the above. At 
http://www.azom.com/details.asp?ArticleID=2626 they do mention a 
coating......

Protective Coatings for Titanium During Forging
Titanium and titanium alloys must be protected from contamination by 
oxygen, nitrogen, hydrogen and carbon during heating for forging. This 
is most effectively done by coating the forging slugs in a liquid glaze 
or glass which is allowed to dry before heating for forging. The 
coating fuses at between 500 and 600°C forming a viscous surface which 
protects the material from contamination. The proprietary liquid glass 
coatings have lubricating properties which assist metal flow during 
forging. Some forgers have found that the addition of a liquid based 
graphite to the die surface further improves die life and metal flow.



They also mention this....



Contamination During Forging
Despite the protection offered by the glass coating, a small amount of 
contamination does occur and must be removed by grinding or chemical 
etching.

When forging titanium, care should be taken to prevent contact with 
steel scale. A thermal type reaction can occur and seriously damage a 
forging die. Apparently the titanium reduces iron oxide in an 
exothermic reaction set off by pressure and high temperature.



I didn't know that! either. I guess wiping off the anvil between steel 
and titanium forging would be a good idea. Guess I'm just lucky.

It is commercially pure. Got that right.

Bob