I need help please.

Aussie_Paul

A reforming stirrer!!!!!
Joined
Oct 30, 2003
Messages
4,441
Location
Ballarat Australia
Aircraft
None at the moment.
Total Flight Time
Since 1982 Gyro 5000+ mostly instructing, and approx. 200 fixed wing in the late 1960s.
I have had my 6061 T-6 Raf engine mount welded where the cracks developed. Now I have to have it heated to bring it back to T-6. Can anyone help me with the procedure, temp, time, and if quelching is needed?

Aussie Paul.
 
Heat to 970º F, quench in cold water and age for 10 hours at 350º F. From Alcoa Aluminum Handbook.
 
Thanks.

Thanks.

Thanks Chuck. Someone told me to heat it at 350F for 8 hours to age it back to T-6.

I also got this, and don't understand which process I am trying to achieve.
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Metal Suppliers Online: Material Property Data
Aluminum 6061

Specifications
Related Tradenames and Metal Names
Chemistry Data
Welding, Machining/ General Data
Physical Data
Mechanical Data
Links to Related Data



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Specifications
The following specifications cover Aluminum 6061

Chemistry Data :

Aluminum Balance
Chromium 0.04 - 0.35
Copper 0.15 - 0.4
Iron 0 - 0.7
Magnesium 0.8 - 1.2
Manganese 0.15 max
Other 0.15 max
Remainder Each 0.05 max
Silicon 0.4 - 0.8
Titanium 0.15 max
Zinc 0.25 max



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Principal Design Features Probably the most commonly available, heat treatable aluminum alloy.

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Applications Commonly used in the manufacture of heavy-duty structures requiring good corrosion resistance, truck and marine components, railroad cars, furniture, tank fittings, general structural and high pressure applications, wire products, and in pipelines.

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Machinability Machinability in the harder T 4 and T6 tempers is good. It is notably less easy to machine in the annealed temper.

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Forming Easily cold worked and formed in the annealed condition. Stamping, bending, spinning, deep drawing are all readily accomplished using standard methods.

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Welding The alloy has very good welding characteristics and may be welded by all of the common welding techniques. Gas tungsten arc welding is generally used for thin sections (less than 0.032") and gas metal arc welding is used for heavier sections. Use alloy 4043 filler wire for best results, although a decrease in T 6 properties will result.

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Heat Treatment Solution heat treat at 990 F for adequate time to allow for thorough heating and then water quench. Precipitation hardening is done at 320 F for 18 hours and air cool, followed by 350 F for 8 hours and air cooling.

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Forging The alloy is capable of being hot forged at temperatures in the range of 900 F to 750 F.

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Hot Working Hot working may be done in the temperature range of 700 F to 500 F.

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Cold Working Cold working in the O temper condition is readily performed. The alloy is notably less easy to cold form in the T 4 and T 6 tempers.

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Annealing Annealing should be done at 775 F for 2 to 3 hours followed by controlled cooling at 50 f per hour down to 500 F, then air cool.

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Aging The aging precipitation heat treatment is done at 350 F for 8 hours followed by air cooling. This produces the T6 temper.

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Tempering Not applicable.

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Hardening See "Aging".

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Other Physical Props Electrical conductivity 40% of copper.

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Other Mechanical Props Shear strength for O temper is 12 ksi and for T 6 temper it is 30, ksi

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Physical Data : [top]


Density (lb / cu. in.) 0.098
Specific Gravity 2.7
Melting Point (Deg F) 1090
Modulus of Elasticity Tension 10
Modulus of Elasticity Torsion 3.8




Aussie Paul.
 
Precipitation hardening is done at 320 F for 18 hours and air cool, followed by 350 F for 8 hours and air cooling


The Alcoa handbook says about the same thing, Paul. If you cook at 350º for 10 hours, the 18 hour cycle at 320º can be skipped.

Household electric stove ovens generally have a dead band too large for this kind of heat treatment. Meaning the range between off and on of the thermostat.
 
Ok.

Ok.

Thanks Chuck. I will bolt a steel 1/4" plate over the area when finished. I will organise to build something better, but at the moment I can't be out of the air much at all due, to training comittments.

Aussie Paul.
 
Paul, do not try it yourself unless you have a very accurate oven. This process can easily turn out bad and what equipment do you have to verify the outcome! All my heat treating goes to Heat Treatments in NZ. I'm sure you have someone equivalent in AU. to use, heat treating aluminium is not a game! What welding rods did you use?
 
Paul not trying jump on your butt, but look what happened to Bill O in florida a month ago.... Your talking about jerry rigging your mount so you can still train while waiting for your new mount. Sounds like to me your putting your students lives in dangar rather than putting them off for a week or two while you get your new mount. I am surprised none of the safety Nazis here didn't already jump your Butt for this Paul.
 
Hi Paul, I vote for new parts too. Aluminum has fatigue challanges to begine with, it is easy to create a stress riser when welding. Even if you do well with the heat treating, the vibration can still creat a problem at the weld. TIG welding aluminum is very easy to screw up as far as smooth and penitration goes. Look at the back of the weld to see how smooth the penitration is.

When building things such as gas tanks where I am going to beat the area of the weld, like vibration does, I like to gas weld because it is less likely to crack along the weld as I form it. This is just my opinion, so please no lectures from you TIG enthusiasts.

Virgin aluminum is much better. Take the time to do it corectly because you can't fix it on the way down. Thank You, Vance

PS. I am on my way to Texas, will be back in a couple of weeks.
 
Thanks guys.

Thanks guys.

I have had it welded by an approved certified aviation welder, and then heat treated by a professional heat-treating company.

Then, unnecessarily according to these people, I have plated the area using one hole that is already in the mount, and another that I drilled in an area that is well over strength.

New is not an option because I don't want to replace it with another Raf mount the same as cracked. A new one will be designed and tested before being used on my trainer.
Ron, you said, "Sounds like to me your putting your students lives in dangar rather than putting them off for a week or two while you get your new mount."

No Ron, that is not the case. Stuff the student’s safety, I am far more important than them!!!!!!!! Seriously. I get your point though. Business pressure can, if you let it, lead one to take short cuts. I know myself well enough to be very aware of this.

That is why I did not just jump in and do something without getting advice from the experts in this area on this forum.

Aussie Paul.
 
Good on you Paul, Would you make a new one from steel tube? Seal weld it then add pressure, connect to a gadge in the dash, then you will know instantly there is a crack forming. This is what Dominator NZ customers get as standard! Also forward mast.

Neil
 
That's fine with me Ron.

That's fine with me Ron.

I'm here, you're there, I know what it all looks like, you don't, I got advice and made a decision. You have made your decision based on?

So never mind, I'm not. ;) LOL.

Aussie Paul.:D
 
Yes Neil,

Yes Neil,

All the important bits on Firebird are done that way. Hybrid is a mix and match of all sorts of things. The stepping stone of trial and error to Firebird.

I am coming to the south Island next Thursday for 10 days to set up a modified Raf and to get Mick Branigan up to speed as an instructor who will train new instructors. Mick is a very experienced train the trainer person.

Do you know him?

Aussie Paul.
 
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