Anti_Candescent
Enlightened
- Joined
- Mar 20, 2004
- Messages
- 240
When heating titanium to shape it, should you let it cool down slowly or submerge it in water? I'm asking which method to keep the most stregnth. Thanks anyone that knows.
Titanium question
- Thread starter Anti_Candescent
- Start date
Help Support Candle Power Flashlight Forum
Shape it? As in forging? Or shape it as in casting, or powder metal sintering, or whatever? Machining titanium doesn't generally require heating it as part of the machining operation.
It highly depends on the alloy and the service temperature and the desired properties.
Remember that titanium must be protected from the atmosphere during heat treatment via vacuum or inert gas blanket (vacuum is usually better).
IMHO, shape the parts in a soft condition and heat treat to the desired properties at the end. Intermediate stress relieving and/or annealing steps may be needed during the forming/shaping process depending on part size and shape complexity.
It highly depends on the alloy and the service temperature and the desired properties.
Remember that titanium must be protected from the atmosphere during heat treatment via vacuum or inert gas blanket (vacuum is usually better).
IMHO, shape the parts in a soft condition and heat treat to the desired properties at the end. Intermediate stress relieving and/or annealing steps may be needed during the forming/shaping process depending on part size and shape complexity.
Anti_Candescent
Enlightened
- Joined
- Mar 20, 2004
- Messages
- 240
I didn't know about needing a vacuum....Its a titanium bar that has been drawn in a machine to bend it, I want to straighten it in places and don't think I would be able to unless I heat it up first, but now that looks like it wouldn't work either......thanks for the info Moonrise.
Titanium crow bar? I'd guess that the manufacturer bent it while in the soft annealed condition and then heat treated it to harden it.
Heat treating titanium properly is not the sort of thing you can really do at home with the kitchen oven or a gas torch. Not enough temperature or control on the temperature or both. And that doesn't even include the inert gas or vacuum requirement. You'd probably just make a mess of the bar's mechanical properties.
Like I said originally, a lot depends on the specific titanium alloy and the current condition and the desired end result.
Heat treating titanium properly is not the sort of thing you can really do at home with the kitchen oven or a gas torch. Not enough temperature or control on the temperature or both. And that doesn't even include the inert gas or vacuum requirement. You'd probably just make a mess of the bar's mechanical properties.
Like I said originally, a lot depends on the specific titanium alloy and the current condition and the desired end result.
mrsinbad
Enlightened
I used to be quite into knifemaking and all the knives made out of titanium 6AL4V test out at about 45 on the Rockwell C scale. I don't recall anything about forging it to a higher hardness, but most of the makers were using the stock removal method anyway.
When you say strength, that means different things when you have different uses for it. If you want it for a cutting instrument, it's better off if you harden the tool, but if you will be prying with it, it may be better if it was more flexible. If you really want to spend a few more bucks, you can send it to a heat treater like Paul Bos out on the west coast. I use him for heat treating my knives, but be fore warned that he charges by the inch and may not be tempering titanium at all. Look him up on the web and see what info you can get. I can't because of the firewall at work and that is a restricted site for me. Let us know what you learn.
When you say strength, that means different things when you have different uses for it. If you want it for a cutting instrument, it's better off if you harden the tool, but if you will be prying with it, it may be better if it was more flexible. If you really want to spend a few more bucks, you can send it to a heat treater like Paul Bos out on the west coast. I use him for heat treating my knives, but be fore warned that he charges by the inch and may not be tempering titanium at all. Look him up on the web and see what info you can get. I can't because of the firewall at work and that is a restricted site for me. Let us know what you learn.
ErickThakrar
Enlightened
Only beta titanium alloys can be hardened. The alpha alloys like 6AL4V are not hardenable.
6AL4v can however be bent easier if it's heated to a dull red glow. You heat it like that, even with just a torch, you can bend it at angles that would make it break otherwise.
6AL4v can however be bent easier if it's heated to a dull red glow. You heat it like that, even with just a torch, you can bend it at angles that would make it break otherwise.
elcaminoreal
Newly Enlightened
anybody know where to find info on welding Ti? somebody told me only the russians knew how to do it. somebody else said it just requires a lot of gas.
I think it has to be done in an inert atmosphere. Search through old Google Groups postings. Lots of discussion. If you want to ask a new question point your newsreader to sci.engr.joining.welding.
I believe you can get an alpha surface, even on 6-4 and its brittlness can cause problems. I seem to recall that 6-4 can be heat treated but I suppose I am wrong. /ubbthreads/images/graemlins/blush.gif I have welded Ti for fun for many years and seen some great looking welds that shattered like glass! As stated, you need to flood not only the weld but the rest of the metal that reaches a reactive temperature or you will get contamination from the atmosphere. You can also get contamination from surface impurities if the metal is not cleaned properly. Even the welding rod needs to be properly stored and addressed as a source of contamination. /ubbthreads/images/graemlins/icon15.gif
There was some story about some heavy forged Ti parts that were aerospace and many failed. Upon investigation, the cause was attributed to parts made in the summer when the clorine content in the municipal water was increased due to evaporation or something like that. The water was used for cooling and ended up contaminating these landing struts (if I recall correctly)
The only thing I *am* certain of is that Ti must be handled properly and not in the typical garage if you plan to take advantage of its real potential or plan to depend on it for anything important!
For some real interesting fun, play with some nitinol!
There was some story about some heavy forged Ti parts that were aerospace and many failed. Upon investigation, the cause was attributed to parts made in the summer when the clorine content in the municipal water was increased due to evaporation or something like that. The water was used for cooling and ended up contaminating these landing struts (if I recall correctly)
The only thing I *am* certain of is that Ti must be handled properly and not in the typical garage if you plan to take advantage of its real potential or plan to depend on it for anything important!
For some real interesting fun, play with some nitinol!
ErickThakrar
Enlightened
Bending it with heating does not have to be done in an inert atmosphere. I've made pocket clips out of titanium and my first attempts were complete failures as the metal simply wouldn't bend the way I wanted it to, without fracturing fatally. Heating it til it glowed red, enabled me to bend it quite nicely into the required shapes and the bends have not shown any significant loss of strength.
Expect the surface to take on several different colors as the titanium reacts with atmosphere. Other than that, you should be fine.
Expect the surface to take on several different colors as the titanium reacts with atmosphere. Other than that, you should be fine.
I have had similar experence and success in heating Ti to glowing and then bending it. Whether there is any contamination or change in its physicals, I can't say but it has not failed in the applications I have used it in. Its melting point is pretty high up there and I would guess you would have to get it really hot to get it to react with other elements.
ErickThakrar
Enlightened
Yeah, pretty much. The reason why you have to flood it with an inert atmosphere while welding it, is simply to stop the surface from oxidizing which messes up the welds. You can't get a solid join with the surface covered in Ti oxide. This is simply not an issue with heating for bending.
Erick,
There may be more to the contamination and not just Ti oxide as issues in the weld. I seem to recall nitrogen embrittlement mentioned. The chlorine in the hot forged part was also a problem. I mentioned my weld failures once to a friend and former neighbor and boss who headded the R&D for an aerospace fastener manufacturer in So. Cal. He suggested that part of my problem was likely alpha case on the surface and suggested that I grind down .004" or .005" from the surface of the weld to remove the alpha. The material was 6-4 and I do recall that the weld bead was like ceramic compared to the rest of the material. Even when I ground some of the weld off, when anodizing, the weld would not oxidize with a resulting color as would the rest of the material. There was some change to the grain or alloy beyond just the weld itself and I attribute this to a change or possible contamination of the Ti itself due to the high heat generated. /ubbthreads/images/graemlins/icon3.gif
Again, I may have the facts confused but I believe I was told by a mechanic that the guys working on exotic aircraft parts did not use chrome sockets and wrenches due to possible contamination from the chrome or nickle as particles might be imparted to the Ti components.
Since we'aren't engaged in rocket science here it is likely all moot. /ubbthreads/images/graemlins/smile.gif
Further, my confidence in recall is so poor that at best I may give proper call for caution and at worst am totaly off base and a source of disinformation. With the possibility of the latter being the case. I'll shut up now! /ubbthreads/images/graemlins/blush.gif
There may be more to the contamination and not just Ti oxide as issues in the weld. I seem to recall nitrogen embrittlement mentioned. The chlorine in the hot forged part was also a problem. I mentioned my weld failures once to a friend and former neighbor and boss who headded the R&D for an aerospace fastener manufacturer in So. Cal. He suggested that part of my problem was likely alpha case on the surface and suggested that I grind down .004" or .005" from the surface of the weld to remove the alpha. The material was 6-4 and I do recall that the weld bead was like ceramic compared to the rest of the material. Even when I ground some of the weld off, when anodizing, the weld would not oxidize with a resulting color as would the rest of the material. There was some change to the grain or alloy beyond just the weld itself and I attribute this to a change or possible contamination of the Ti itself due to the high heat generated. /ubbthreads/images/graemlins/icon3.gif
Again, I may have the facts confused but I believe I was told by a mechanic that the guys working on exotic aircraft parts did not use chrome sockets and wrenches due to possible contamination from the chrome or nickle as particles might be imparted to the Ti components.
Since we'aren't engaged in rocket science here it is likely all moot. /ubbthreads/images/graemlins/smile.gif
Further, my confidence in recall is so poor that at best I may give proper call for caution and at worst am totaly off base and a source of disinformation. With the possibility of the latter being the case. I'll shut up now! /ubbthreads/images/graemlins/blush.gif
ErickThakrar
Enlightened
No no, I think you're right. Now that you bring it up, the contamination from nitrogen and even from tools rings a distinct bell. It's been ages since I studied up on this stuff.
