Annealing aluminium and vice versa
11-20-2008, 12:33 PM
#1
Thread Starter
Annealing aluminium and vice versa
One year back or so, I asked in this forum how I could possibly re-harden the aluminium landing gear of my large Extra 230 that I had accdentally annealed when I soldered a reiforcement on it. After that soldering work the landing gear became so soft that I could not fly anymore.
Then one buddy, whose name I have forgotten, replied me saying that I should have put the aluminium gear in an oven at 180 C for 18 hours. I was a bit skeptical and, beside it, I had to wait for my wife not to be around, so that it took a long while before I could give it a try.
Well, the landing gear is now stiffer than I could ever expect. I am back to the flying field with the Extra 230. I can bounce on the runway asphalt like a kangaroo and the thing does not bend at all.
Amazing. This tecnique can be intentionally used to manufacture wonderful aluminium works.
Then one buddy, whose name I have forgotten, replied me saying that I should have put the aluminium gear in an oven at 180 C for 18 hours. I was a bit skeptical and, beside it, I had to wait for my wife not to be around, so that it took a long while before I could give it a try.
Well, the landing gear is now stiffer than I could ever expect. I am back to the flying field with the Extra 230. I can bounce on the runway asphalt like a kangaroo and the thing does not bend at all.
Amazing. This tecnique can be intentionally used to manufacture wonderful aluminium works.
11-21-2008, 11:46 AM
#2
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RE: Annealing aluminium and vice versa
I believe you would have the same result, from this artificial aging process, after 8 hours.
You may try to explain that the aluminum is clean and will not affect the oven. Unlike used car parts, my wife will allow new, clean, unpainted metal in the oven. She does not like me heating engines so I can pop the bearings out, so that is done in a toaster oven in the garage.
Jack
You may try to explain that the aluminum is clean and will not affect the oven. Unlike used car parts, my wife will allow new, clean, unpainted metal in the oven. She does not like me heating engines so I can pop the bearings out, so that is done in a toaster oven in the garage.
Jack
11-22-2008, 10:01 AM
#3
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RE: Annealing aluminium and vice versa
ORIGINAL: jib
I believe you would have the same result, from this artificial aging process, after 8 hours.
You may try to explain that the aluminum is clean and will not affect the oven. Unlike used car parts, my wife will allow new, clean, unpainted metal in the oven. She does not like me heating engines so I can pop the bearings out, so that is done in a toaster oven in the garage.
Jack
I believe you would have the same result, from this artificial aging process, after 8 hours.
You may try to explain that the aluminum is clean and will not affect the oven. Unlike used car parts, my wife will allow new, clean, unpainted metal in the oven. She does not like me heating engines so I can pop the bearings out, so that is done in a toaster oven in the garage.
Jack
Your correct about the time being too long and 8 hrs being about right. Temperature is usually 350 degrees for 8 hours, if thin you can do 370 for 6 hours.
To anneal raise temp to 800 for 2 hours, then slow cool 50 degrees per hour to 550 then remove from oven and allow to air cool. Tou will then have a 0 temper aluminum.Needless to say your convertional household oven will not be suitable for the annealing process.
I've had a lot of years in the aluminum industry doing this work.
dennis
11-22-2008, 10:51 AM
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RE: Annealing aluminium and vice versa
Hey Dennis,
Just for grins, I'm thinking about that anneal cycle in a home oven. The clean cycle on a home oven is somewhere in the 800-900F range, but it will probably drop in temperature faster than 50F/hour. The lock on the door should open up somewhere above 550F, because that is the highest cooking setting on my oven. I’m thinking that a home oven, while not optimal, might just work for a “ballpark” annealing. Your thoughts?
Also, for PiccoLino, who started this thread, are there any downsides for an 18 hour soak at 350F versus an 8 hour soak or is it just a waste of energy?
Jack - Mechanical Enginerd, with good materials background, but definitely not a metallurgist
Just for grins, I'm thinking about that anneal cycle in a home oven. The clean cycle on a home oven is somewhere in the 800-900F range, but it will probably drop in temperature faster than 50F/hour. The lock on the door should open up somewhere above 550F, because that is the highest cooking setting on my oven. I’m thinking that a home oven, while not optimal, might just work for a “ballpark” annealing. Your thoughts?
Also, for PiccoLino, who started this thread, are there any downsides for an 18 hour soak at 350F versus an 8 hour soak or is it just a waste of energy?
Jack - Mechanical Enginerd, with good materials background, but definitely not a metallurgist
11-22-2008, 12:41 PM
#5
Senior Member
RE: Annealing aluminium and vice versa
GUYS PLEASE!
In my opinion you are taking a big risk with this method!
You are not annealing it, you are AGING the aluminum!
Your landing gear made of aluminum 2xxxTx, look at the “T”!!!
This aluminum is hardened by mechanism of precipitation.
Some basic metallurgy:
Precipitation hardening is like a cake with nuts; you cut it with a knife and when the knife meets a nut it’s hard to pass it so you need to apply more force to cut it.
The knife is your crack or fracture that moves.
In aluminum alloys with “T” you plant these “nuts” so the crack will meet these nuts and will not proceed.
When manufactured, these alloys go a process of tempering to reduce stress.
If you continue with this elevated temperature process all the atoms of the hardening/alloying element will defuse to create these pockets of the alloying elements.
And the strengthening you see after your heat treatment is actually strengthening by grain boundaries which are much weaker. (see my quote: 99.99% of problems are in the interface. )
These Aluminum parts you think you “hardened” are just aged and they are much less predictable and much easier to brake.
I’m a materials engineer = metallurgist and I worked a lot studying these particular processes of recycling aluminum waste and its mechanical properties.
Alex
11-22-2008, 01:31 PM
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RE: Annealing aluminium and vice versa
Alex,
So what we have created is hardened, but untempered material?
Please recall that I stated in post #2 that this was an artificial aging process. Speaking for myself, I have trouble finding T6 to make landing gear out of, so I've used very soft harware store grade Aluminum (no designation on it), bend it to shape and artificially age it for 8 hours at 350°, followed by an air cool. It definitely toughenes the metal and while I've never broken landing gear like this, I've never rebent it after this heat process either.
Yes, I understand that we are growing metal crystals in the Aluminum to gain this toughness. Nothing is free, there are always tradeoffs, but so far, I have not had an issue, perhaps it's because the material is highly understressed.
Thanks for your education though. It definitely helps me understand a little better how things work in Aluminum.
Jack
So what we have created is hardened, but untempered material?
Please recall that I stated in post #2 that this was an artificial aging process. Speaking for myself, I have trouble finding T6 to make landing gear out of, so I've used very soft harware store grade Aluminum (no designation on it), bend it to shape and artificially age it for 8 hours at 350°, followed by an air cool. It definitely toughenes the metal and while I've never broken landing gear like this, I've never rebent it after this heat process either.
Yes, I understand that we are growing metal crystals in the Aluminum to gain this toughness. Nothing is free, there are always tradeoffs, but so far, I have not had an issue, perhaps it's because the material is highly understressed.
Thanks for your education though. It definitely helps me understand a little better how things work in Aluminum.
Jack
11-22-2008, 02:12 PM
#7
Senior Member
RE: Annealing aluminium and vice versa
Jack,
There are several Aluminum alloys
1xxxHx
2xxxTx windows frame, profiles
3xxxHx shining, floor, thin sheets
4xxxTx
5xxxHx gray in color- for welding, sheets
6xxxTx common for machining, rolls
7xxxHx machining - aerospace industry, rolls
You can find 2024T6 and 6061T651 these are most common.
Aluminum with T in it cannot undergo heat treatment.
Aluminum with H can undergo heat treatment, the heat treatment doesn’t influence it, they are expensive.
What you do with heat treatment to T alloys is you make the atoms of the alloying element to defuse from the aluminum matrix to alloying element grain boundaries and create chunks of the same element.
what else is happening that these boundaries are may be stronger then the soft material, BUT the strengthening mechanism (precipitation) doesn’t exist any more, the crack can travel freely.
My bet that this part will rake sooner or later, it doesn’t contain the initially designed characteristics any more.
My guesses to explain why your landing gear didn’t brake yet is maybe it’s not 2024T6 and not influenced by heat treatment or you didn’t allow it enough time for significant aging which I doubt.
You are just taking a risk doing a heat treatment to aluminum, I would buy a new landing gear.
And for sure won’t weld aluminum, its loosing all its mechanical properties.
Alex
There are several Aluminum alloys
1xxxHx
2xxxTx windows frame, profiles
3xxxHx shining, floor, thin sheets
4xxxTx
5xxxHx gray in color- for welding, sheets
6xxxTx common for machining, rolls
7xxxHx machining - aerospace industry, rolls
You can find 2024T6 and 6061T651 these are most common.
Aluminum with T in it cannot undergo heat treatment.
Aluminum with H can undergo heat treatment, the heat treatment doesn’t influence it, they are expensive.
What you do with heat treatment to T alloys is you make the atoms of the alloying element to defuse from the aluminum matrix to alloying element grain boundaries and create chunks of the same element.
what else is happening that these boundaries are may be stronger then the soft material, BUT the strengthening mechanism (precipitation) doesn’t exist any more, the crack can travel freely.
My bet that this part will rake sooner or later, it doesn’t contain the initially designed characteristics any more.
My guesses to explain why your landing gear didn’t brake yet is maybe it’s not 2024T6 and not influenced by heat treatment or you didn’t allow it enough time for significant aging which I doubt.
You are just taking a risk doing a heat treatment to aluminum, I would buy a new landing gear.
And for sure won’t weld aluminum, its loosing all its mechanical properties.
Alex
11-22-2008, 03:19 PM
#8
My Feedback: (90)
RE: Annealing aluminium and vice versa
ORIGINAL: alex7403
Jack,
There are several Aluminum alloys
1xxxHx
2xxxTx windows frame, profiles
3xxxHx shining, floor, thin sheets
4xxxTx
5xxxHx gray in color- for welding, sheets
6xxxTx common for machining, rolls
7xxxHx machining - aerospace industry, rolls
You can find 2024T6 and 6061T651 these are most common.
Aluminum with T in it cannot undergo heat treatment.
Aluminum with H can undergo heat treatment, the heat treatment doesn’t influence it, they are expensive.
What you do with heat treatment to T alloys is you make the atoms of the alloying element to defuse from the aluminum matrix to alloying element grain boundaries and create chunks of the same element.
what else is happening that these boundaries are may be stronger then the soft material, BUT the strengthening mechanism (precipitation) doesn’t exist any more, the crack can travel freely.
My bet that this part will rake sooner or later, it doesn’t contain the initially designed characteristics any more.
My guesses to explain why your landing gear didn’t brake yet is maybe it’s not 2024T6 and not influenced by heat treatment or you didn’t allow it enough time for significant aging which I doubt.
You are just taking a risk doing a heat treatment to aluminum, I would buy a new landing gear.
And for sure won’t weld aluminum, its loosing all its mechanical properties.
Alex
Jack,
There are several Aluminum alloys
1xxxHx
2xxxTx windows frame, profiles
3xxxHx shining, floor, thin sheets
4xxxTx
5xxxHx gray in color- for welding, sheets
6xxxTx common for machining, rolls
7xxxHx machining - aerospace industry, rolls
You can find 2024T6 and 6061T651 these are most common.
Aluminum with T in it cannot undergo heat treatment.
Aluminum with H can undergo heat treatment, the heat treatment doesn’t influence it, they are expensive.
What you do with heat treatment to T alloys is you make the atoms of the alloying element to defuse from the aluminum matrix to alloying element grain boundaries and create chunks of the same element.
what else is happening that these boundaries are may be stronger then the soft material, BUT the strengthening mechanism (precipitation) doesn’t exist any more, the crack can travel freely.
My bet that this part will rake sooner or later, it doesn’t contain the initially designed characteristics any more.
My guesses to explain why your landing gear didn’t brake yet is maybe it’s not 2024T6 and not influenced by heat treatment or you didn’t allow it enough time for significant aging which I doubt.
You are just taking a risk doing a heat treatment to aluminum, I would buy a new landing gear.
And for sure won’t weld aluminum, its loosing all its mechanical properties.
Alex
Alex,
I've sent you a PM on the matter but just so the origional respondant knows that you are correct about T-1/2/3/4 metal. My response was assuning that he was using 6061T6 or 6511 as these are the most commonly used alloys for L/G. Tto5 and other types are never hardened but usually undergo a realignment as the material sits. Most other alloys 2/3/4/5/ that are available are indeed too soft and as stated hardening as described will not improve their strength. Indeed even with an optimal ageing process can never approach the hardness of 6061 or the 'hard alloys' ex 2024 ot 7075
However there is some descrepency in practice as many of the T types above 5 are aged and have always been. Unless your using something completely new or I'm on a different page
As for welding Aluminum, if your not certified and don't have the correct equipment your more then likely to have a disappointment in the making. I don't know of many people having the equipment and Argon gas available to do the process correctly.
11-22-2008, 03:31 PM
#9
Senior Member
RE: Annealing aluminium and vice versa
just making sure we are on the same page, 
Who needs to weld aluminum is no beginner, its probably expensive airplane, so don’t try welding aluminum, its cheaper to buy anew landing gear.
I’m just reading responses from the ARF & RTF forum and getting horrified. [&:]
Fly safe and make us all enjoy the hobby.
Alex
Who needs to weld aluminum is no beginner, its probably expensive airplane, so don’t try welding aluminum, its cheaper to buy anew landing gear.
I’m just reading responses from the ARF & RTF forum and getting horrified. [&:]
Fly safe and make us all enjoy the hobby.
Alex
11-22-2008, 03:41 PM
#10
My Feedback: (90)
RE: Annealing aluminium and vice versa
Alex not a problem for me as I enjoyed the dialoge. Really the responses had nothing to do with the landing gear as your correctly pointed out, get a new gear and be safe with it. I have 29 years of eexperience in the Aluminum field and while I'm not an engineer I have been a diligent student of my craft.
Welding Aluminum is pretty common nowaday. We have the equipment and do use it. But as I said you really have to know what your doing [certified ]. I've been fortunate to have friends that are able to weld engine cases for me that are about 1/16 thick and do absolutely perfect work.
Have worked with Alumimum for everything from pipe to missle rails. An interesting field.
Dennis
Welding Aluminum is pretty common nowaday. We have the equipment and do use it. But as I said you really have to know what your doing [certified ]. I've been fortunate to have friends that are able to weld engine cases for me that are about 1/16 thick and do absolutely perfect work.
Have worked with Alumimum for everything from pipe to missle rails. An interesting field.
Dennis
11-22-2008, 04:59 PM
#11
Senior Member
RE: Annealing aluminium and vice versa
Dennis,
I pmd you so you wont do it at home, trying to save your airplanes.
just portraying it like you bake a cake made me nervous:
Wife is not home [>:]
You put the aluminum LG in her oven [8D]
Temperature to 180 C [>:]
For 18 hours [:-]
Comes out a……. cake [&o]
Yes sure aluminum is a fabulous metal, no rust, no injuries from chips, just a mischief in wife’s oven…. [8D]
Well that’s BS,
As you said, he who is welding aluminum knows what he is doing (1)
(2) He knows that there is a price to pay in form of mechanical properties.
(3) heat treatment is done in an inert environment of argon or nitrogen or so.
I respect practical experience a lot, just wanted to explain with educational and practical experience that is not as easy as it seems.
Alex
I pmd you so you wont do it at home, trying to save your airplanes.
just portraying it like you bake a cake made me nervous:
Wife is not home [>:]
You put the aluminum LG in her oven [8D]
Temperature to 180 C [>:]
For 18 hours [:-]
Comes out a……. cake [&o]
Yes sure aluminum is a fabulous metal, no rust, no injuries from chips, just a mischief in wife’s oven…. [8D]
Well that’s BS,
As you said, he who is welding aluminum knows what he is doing (1)
(2) He knows that there is a price to pay in form of mechanical properties.
(3) heat treatment is done in an inert environment of argon or nitrogen or so.
I respect practical experience a lot, just wanted to explain with educational and practical experience that is not as easy as it seems.
Alex
11-22-2008, 05:28 PM
#12
My Feedback: (90)
RE: Annealing aluminium and vice versa
ORIGINAL: alex7403
Dennis,
I pmd you so you wont do it at home, trying to save your airplanes.
just portraying it like you bake a cake made me nervous:
Wife is not home [>:]
You put the aluminum LG in her oven [8D]
Temperature to 180 C [>:]
For 18 hours [:-]
Comes out a……. cake [&o]
Yes sure aluminum is a fabulous metal, no rust, no injuries from chips, just a mischief in wife’s oven…. [8D]
Well that’s BS,
As you said, he who is welding aluminum knows what he is doing (1)
(2) He knows that there is a price to pay in form of mechanical properties.
(3) heat treatment is done in an inert environment of argon or nitrogen or so.
I respect practical experience a lot, just wanted to explain with educational and practical experience that is not as easy as it seems.
Alex
Dennis,
I pmd you so you wont do it at home, trying to save your airplanes.
just portraying it like you bake a cake made me nervous:
Wife is not home [>:]
You put the aluminum LG in her oven [8D]
Temperature to 180 C [>:]
For 18 hours [:-]
Comes out a……. cake [&o]
Yes sure aluminum is a fabulous metal, no rust, no injuries from chips, just a mischief in wife’s oven…. [8D]
Well that’s BS,
As you said, he who is welding aluminum knows what he is doing (1)
(2) He knows that there is a price to pay in form of mechanical properties.
(3) heat treatment is done in an inert environment of argon or nitrogen or so.
I respect practical experience a lot, just wanted to explain with educational and practical experience that is not as easy as it seems.
Alex
Dennis
11-22-2008, 05:58 PM
#13
Senior Member
RE: Annealing aluminium and vice versa
I have a good story for you,
Once many years ago in some country’s mighty air force there was a mechanical engineer and he made an improvement proposal;
You know jet fighters shooting flares to confuse heat seeking missiles, these flares are held in a tube with a pin and when the flare is being shot it brakes the pin and flies out of the tube.
These pins are made of hast alloy and were cost $100 each.
He measured the UTS – ultimate tensile strength point of this alloy and said “I can find some cheaper metal with these dimension and that UTS that doesn’t cost $100 pin”.
He choose steel, the only thing he didn’t know that area under the curve is the energy that you need to invest in order to brake the pin.
Well the pin didnt brake and flare didn’t release from the tube and the pilot had to eject from the burning airplane.
Once many years ago in some country’s mighty air force there was a mechanical engineer and he made an improvement proposal;
You know jet fighters shooting flares to confuse heat seeking missiles, these flares are held in a tube with a pin and when the flare is being shot it brakes the pin and flies out of the tube.
These pins are made of hast alloy and were cost $100 each.
He measured the UTS – ultimate tensile strength point of this alloy and said “I can find some cheaper metal with these dimension and that UTS that doesn’t cost $100 pin”.
He choose steel, the only thing he didn’t know that area under the curve is the energy that you need to invest in order to brake the pin.
Well the pin didnt brake and flare didn’t release from the tube and the pilot had to eject from the burning airplane.
11-22-2008, 06:07 PM
#14
My Feedback: (1)
RE: Annealing aluminium and vice versa
This has been an interesting discourse on aluminum. Wish I knew more about it. When you speak of heating Al to 1370 and throwing water on it, is the result similar to dropping a hard-frozen turkey into a hot deep fryer?
11-22-2008, 06:58 PM
#16
My Feedback: (90)
RE: Annealing aluminium and vice versa
ORIGINAL: khodges
This has been an interesting discourse on aluminum. Wish I knew more about it. When you speak of heating Al to 1370 and throwing water on it, is the result similar to dropping a hard-frozen turkey into a hot deep fryer?
This has been an interesting discourse on aluminum. Wish I knew more about it. When you speak of heating Al to 1370 and throwing water on it, is the result similar to dropping a hard-frozen turkey into a hot deep fryer?
Yea, it does blow up violently. there have been a few plants that have had cast houses go up as a result of water contact with molten aluminum. Alex makes good sense pays to listen to him on this. I only cited Aluminum because of it's low melting point.Easily done with propane torch and carelessness. Really nothing more to say on this topic.
Dennis
12-03-2008, 10:14 AM
#17
Thread Starter
RE: Annealing aluminium and vice versa
I have found your posts (except the one about frozen turkey) very interesting. Of course I was not aware of what I was going to do while baking my LG in the oven, however I can scientifically report that the thing works. I would not be afraid of nuts (I am used to them. Plenty down here....) in my LG that can trig fractures because I believe that the mechanical stress is not "that" consistent in a model airplene LG to cause it to break so promptly.
Apart of that we often overestimate the life span of our airplane and we adopt technical solution as they were supposed to last forever. For most of the buddies here 10 - 20 landings is more than enough duration for the LG of their airplanes.
Obviously making an engine mount with this technique would be a different story and I am sure that nobody meant that in this thread so far.
Although a bit discourteous, huge red capital letter are welcome especially for long shighted persons like I am.
Thanks for your participation.
Apart of that we often overestimate the life span of our airplane and we adopt technical solution as they were supposed to last forever. For most of the buddies here 10 - 20 landings is more than enough duration for the LG of their airplanes.
Obviously making an engine mount with this technique would be a different story and I am sure that nobody meant that in this thread so far.
Although a bit discourteous, huge red capital letter are welcome especially for long shighted persons like I am.
Thanks for your participation.
12-03-2008, 10:40 AM
#18
Senior Member
RE: Annealing aluminium and vice versa
ORIGINAL: PiccoLino
Although a bit discourteous, huge red capital letter are welcome especially for long shighted persons like I am.
Thanks for your participation.
Although a bit discourteous, huge red capital letter are welcome especially for long shighted persons like I am.
Thanks for your participation.
Red capital letters are for guys like me who might not read through all the posts and just read the first one and answer it.
This subject brought up and I saw where its going so I thought what I had to say is important because of the consequences of this treatment.
you read it and you decide what you gonna do with it.
I didn’t mean to discourage you not at all.
Alex
