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Engine basics => Engine set up tips => Topic started by: Lauri Malila on January 23, 2014, 12:36:53 PM
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Hello.
I'm making new mufflers from #6262 aluminium alloy. I like them thin-walled, and they are assembled by brazing.
Can anyone say if there is any easy heat tratment for re-gaining the hardness that is lost in brazing. Something I could do at home.
Thanks in advance,
Lauri
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Hello.
I'm making new mufflers from #6262 aluminium alloy. I like them thin-walled, and they are assembled by brazing.
Can anyone say if there is any easy heat tratment for re-gaining the hardness that is lost in brazing. Something I could do at home.
Thanks in advance,
Lauri
Depending on what other metals are in your alloy? one of them ,6061 can be, so maybe your in luck, you can use this technique ,Precipitation hardening, which is also called age hardening , you will need to find the melt point of your alloy, and heat it to just below that point, keep it there for several hours, then after rapid cooling you can put it away for a few weeks while it hardens, or you can heat cycle it many times, 200, 300 and up to 500 degrees. How many depends on your alloy matrix. But it will harden at room temp, just takes a long time
For a muffler I doubt you need this though??
Why not just use 2024 -T351 or 7075 alloy?
Randy
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Thanks, Randy.
Yep, I think that the methods you described also work with 6262. Gotta study a little.
I use 6262 because it's easy to braze. It is also a little stronger than the std free machining grade, plus a bit nicer to machine. L
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6262 T-6 is generally used for the hardware type screws and nuts. It has lead alloyed into It and is softer. Now you know why it round off so badly. I probably aged a few million pounds of it in my career as we supplied a lot of manufacturers with this alloy. Your right though, the lead makes it easy to machine. There is a slight difference between 6262-T6 and T6511 the most common alloys. I'd be reluctant to offer hardening advise on brazed metal, I'm not a metallurgist.
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I'm a metallurgist. For solution Ht you need 975F for at least 8 hrs followed by rapid quenching. Then age 350-375F for 6-8 hours. You can Google commercial heat treat shops that have furnaces and expertise to do this type work.
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Below are some mechanical properties of many alloys of aluminum , maybe a help in picking alloys, you can also try to use some Gold Tap magic when you machine al. it makes it easier for me, and you get an excellent finish. This may come in handy if, you run into problems trying to heat treat Metal that you have brazed.. Another alloy may be better suited
Alloy Temper , Elastic Modulus - E - (106 psi) ,Shear Modulus- G -(106 psi) , Yield Strength(103 psi) ,Tensile Strength (103 psi
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1100 10.0 3.75 3.5 11
1100 H12 10.0 3.75 11 14
2014 10.8 4.00 8 22
2014 T6 10.6 4.00 58 66
2014 T62 10.8 4.00 59 67
2017 T4 10.5 3.95 32 55
2024 T3 10.6 4.00 42 64
2024 T4 10.6 4.00 40 62
2025 T6 10.4 3.90 33 52
2124 T851 10.4 4.00 57 66
2219 T62 10.5 4.00 36 54
2618 T61 10.7 4.10 42 55
3003 10.0 3.75 5 14
3003 H18 10.0 3.75 25 27
3003 H112 10.0 3.75 10 17
354 T61 10.6 4.00 36 47
355 T51 10.2 3.80 22 27
355 T6 10.3 3.80 23 37
356 T7 10.3 3.85 21 29
356 T6 10.3 3.85 20 30
5052 10.2 3.80 9.5 25
5052 H32 10.2 3.80 23 31
5056 H38 10.3 3.75 50 60
5056 ANL 10.3 4.00 22 42
6061 T4 10.0 3.80 16 30
6061 T6 10.0 3.80 35 42
6062 10.0 3.75 5 14
6062 T4 10.0 3.75 16 26
6062 T6 10.0 3.75 35 38
6063 T42 10.0 3.75 10 17
6063 T5 10.0 3.75 16 22
6063 T6 10.0 3.75 25 30
6151 T6 10.1 3.85 37 44
7075 T6 10.4 3.90 70 78
A356 T61 10.4 3.90 28 38
D712 T5 10.3 3.80 20 32
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And here are Thermal Properties of the 6000 series alloy
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CTE, linear 68°F 23.4 µm/m-°C 13 µin/in-°F AA; Typical; Average over 68-212°F range.
CTE, linear 250°C 25.6 µm/m-°C 14.2 µin/in-°F Average over the range 20-300ºC
Specific Heat Capacity 0.9 J/g-°C 0.215 BTU/lb-°F
Thermal Conductivity 200 W/m-K 1390 BTU-in/hr-ft²-°F AA; Typical at 77°F
Melting Point 616 - 654 °C 1140 - 1210 °F AA; Typical range based on typical composition for wrought products 1/4 inch thickness or greater
Solidus 616 °C 1140 °F AA; Typical
Liquidus 654 °C 1210 °F AA; Typical
Processing Properties
Annealing Temperature 413 °C 775 °F hold at temperature for 2 to 3 hr; cool at 50°F per hour from 775 to 500°F
Solution Temperature 521 °C 970 °F
Aging Temperature 177 °C 350 °F hold at temperature for 8 hr
Regards
Randy
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Thanks for info. The parts are only end caps for the muffler, they are glued to the center part thats made from good dural tube. So the heat treatment is not highly necessary. However, If there is something I could do to improve it, I'd like to give it a try.
The braze i use melts at around 580c (1076F), sovI don't want to go near that limit in the process and neither do I have an owen where to keep the parts for longer periods of time. But ageing in raised temperature should not be a problem.
So, is there any sense to just make the ageing after brazing (when the parts are kind of annealed)? Should I quench the parts as soin as the braze gets solid.
Sorry, my questions may be stupid.
Lauri
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Parts look like this:
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Thanks for info. The parts are only end caps for the muffler, they are glued to the center part thats made from good dural tube. So the heat treatment is not highly necessary. However, If there is something I could do to improve it, I'd like to give it a try.
The braze i use melts at around 580c (1076F), sovI don't want to go near that limit in the process and neither do I have an owen where to keep the parts for longer periods of time. But ageing in raised temperature should not be a problem.
So, is there any sense to just make the ageing after brazing (when the parts are kind of annealed)? Should I quench the parts as soin as the braze gets solid.
Sorry, my questions may be stupid.
Lauri
Hi Lauri
I would have no idea about HT on brazed parts, or for that matter "glued parts" will your glue stand heat over 900 degrees? That would maybe be a trail and error deal.
Lyle is the expert , maybe he would have a suggestion.. HT after brazing maybe a tough thing or it maybe would have no affect on your brazed parts, I know i would look for cracks at or near the brazing, especially after quenching and heat treating.
I have made parts similar to yours, but instead of glue, I used 080 and 256 screws with tiny rounded or countersunk heads, I put them in with RED stud and bearing mount. have ever thought about bolting the parts together?
Randy
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Hi Randy.
Sorry, I was unclear. I use brazing to join the header to front cap and exhaust stinger to the rear cap. Those 2 are glued to the center tube which is thin walled dural. Fur gluing I use 7mm wide overlap joint and JBweld and so far they have stayed well together. The first ones (like the one in picture) were assembled weit silicone glue and screws because I was not sure about carbon buildup, and also wanted some adjustability for baffles. Now, When I've found nearly zero carbon inside and finished with the acoustics, I just glue them together. The baffle section is just pressed in the dural tube with interference fit.
So, I forget the HT, maybe it hardens a bit by itself during time.
Lauri
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Hi Randy.
Sorry, I was unclear. I use brazing to join the header to front cap and exhaust stinger to the rear cap. Those 2 are glued to the center tube which is thin walled dural. Fur gluing I use 7mm wide overlap joint and JBweld and so far they have stayed well together. The first ones (like the one in picture) were assembled weit silicone glue and screws because I was not sure about carbon buildup, and also wanted some adjustability for baffles. Now, When I've found nearly zero carbon inside and finished with the acoustics, I just glue them together. The baffle section is just pressed in the dural tube with interference fit.
So, I forget the HT, maybe it hardens a bit by itself during time.
Lauri
Yes I see the picture you posted, an nice piece of work. If you do any HT on the parts, let us know how that worked out.
Randy
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I recall once asking what was the difference between T6 and T6511 HT, and was told that the T6 means that the HT was done post manufacture (i.e., prior to or after some machining or other processing), and the T6511 was done at the time of manufacture, by ALCOA, Reynolds, etc. Otherwise, the same piece of material, same alloys, same chit.
I'm surprised that Lauri is even using American alloy callouts. What I've seen of European drawings, the alloy designations were different, tho the actual mix of elements could easily be the same. When you get to steel alloys, for instance, there is some overlap between 4140 and 4340, etc. It's all about the tolerances, and there always are some. Otherwise, everything would cost way more than it does, and that's already just plenty. H^^ Steve