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6061 Welding

nilberg

Well Known Member
My RV-7 tip up canopy frame hinges are going to have too little material when I drill them.

Anyone know a good welding service in the Houston area who can TIG weld and add some more material ?
 
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Be very careful of welding 6061 on any stressed part. The welding operation will put the aluminum in the dead soft condition. Most of us do not have facilities to artificially harden.
 
You may want to check with Van's after you drill them, I would bet they would be ok with less than standard ED as the canopy hinges are not considered primary structure. Welding to increase ED would likely be worse than just living with the short ED.
 
I will check with Vans. I did a #40 pilot hole which allowed me to accurately judge the ED by using drill and brass bushings. Unfortunately it looks like the ED on the left is 0. The right is ok, or at least similar to other builders.

I posted in another thread related to the general tip up blues topic. I didn't mean to double post, just to seek local advice on welding service in Houston area.
 
Update

I couldn't find a reasonable quote for welding on material.
I ended up welding the tiny holes shut and drilled new one in the center.
I replaced subpanel ribs and flipped the delrin blocks around and let the tabs decide the hole location.
It's all good now, ready to move on to the remaining parts of the canopy frame.
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I don't think 6061 goes "dead soft" upon welding. The annealing protocol for 6061 is not consistent with the heat cycling achieved with welding.

More likely, you'll achieve a "W" temper condition - usually mistermed as "annealing" which will age harden to T-4 condition.
 
I don't think 6061 goes "dead soft" upon welding. The annealing protocol for 6061 is not consistent with the heat cycling achieved with welding.

More likely, you'll achieve a "W" temper condition - usually mistermed as "annealing" which will age harden to T-4 condition.

Aren't they welded at the factory?

In the RV-6s the hinge "hooks" have tabs welded on them to hold the crossways forward portion of the canopy frame.

Are the -7s built in the same way?
 
I am not an expert, please enlighten me!
6061 is highly weldable, for example using tungsten inert gas welding (TIG) or metal inert gas welding (MIG). Typically, after welding, the properties near the weld are those of 6061-O, a loss of strength of around 80%. The material can be re-heat-treated to restore -T4 or -T6 temper for the whole piece. After welding, the material can naturally age and restore some of its strength as well. Nevertheless, the Alcoa Structural Handbook recommends the design strength of the material adjacent to the weld to be taken as 76 MPa (11,000 psi) without proper heat treatment after the weld.[citation needed] Typical filler material is 4043 or 5356.
 
Gisnar said:

"Typically, after welding, the properties near the weld are those of 6061-O, a loss of strength of around 80%."

I like Alcoa's "Forming Alcoa Aluminum" (in addition to "Welding Alcoa Aluminum") as it goes into detail on Heat Treating. The definitive work is the ASM-4. Both are still in boxes due to a move, so I'm operating from memory.

Annealing, as compared to "W" Temper, requires a programmed rate of temperature drop that cannot be achieved with welding equipment. I also understand that T4 can be pushed by heat treating if time (less than the 3-4 days achieved from simple aging) is critical.

I think your structural book, as well as the books I referenced should be referenced together. I've found from experience that equivalent technical terms can/have been used out of context and can differ significantly between separate works.

FWIW
 
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