builders tips

A forum in which to discuss topics specific to the assembly of the RV 4.
Ronald Sutton
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builders tips

Postby Ronald Sutton » Sat Apr 06, 2013 10:48 pm

To normalize Aluminum sheet or extrusion to an SO state (soft pliable, no memory condtion) for ease of forming. Take an OXY/ACY torch and create a carborizing flame that has black smoke emitting from the tip of the torch. play this smoky soot very lightly over the aluminum part you want to normalize. Then take the OXY/ACY torch and adjust the flame to a neutral flame. Play this neutral fame over the smoky sooty area slowly and lightly. As the part heates up, it will begin to burn off the smoky sooty residue, and the temperature will be 900 to 1000 deg. which is the normalizing temperature of aluminum.
practise on a few scrap pieces of aluminum first to get the timing of the heat being applied to the part. Too much heat will show a discoloration of the aluminim. The just right temp will have a very slight hint of smoky soot left on the part. allow the part to cool at room temerature. Once cooled, you can hand form the aluminum by hand with the grain or across the grain. You can normalize just a small section on a part exactly where you want it :wink:
I built a Witman tailwind 1972
i built a RV4 1991
I bought a RV4 2012

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captain_john
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Postby captain_john » Sun Apr 07, 2013 3:17 am

OK, I will bite on this one.

What is an "SO" state?

I know that you described it as soft and pliable but, how do you get "SO" as a description?

Is this an ASTM term?

I am puzzled?

:? CJ
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TomNativeNewYorker
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Postby TomNativeNewYorker » Sun Apr 07, 2013 7:13 am

captain_john wrote:
What is an "SO" state?

I know that you described it as soft and pliable but, how do you get "SO" as a description?


Going a bit from memory, so it may not be verbatim out of a metallurgical manual, but here goes.

I have a need to fabricate a part/bracket/widget etc and it may have some complex curves or bends. Because of the complexity of the item, I need to use 2024-0 because it is easier to work the metal in "O" condition. After whatever level of fabrication I chose to bring the widget to(I may work it more after heat treat process); comes two parts of the heat treat process.

First is the 'solution heat treat' portion of the process. I suspect that is where the "SO" comes from but not sure. Dont hold me to the book on the temps, but I put my widget into an oven and take it up to 920*F +/- 10* for one hour. This "liquifies" the crystals with the metal grain boundaries.

After the one hour soak time, I pull my widget out of the oven and quench it in water. Now the item is 2024-W or "SO" state. If I desire to tweak the metal a little at this point I may.

Next, comes artificial aging process. This may be 250* F for 24 hours. after that time is when your widget should be up to strength. Usually I throw a few extra scraps of aluminum through the entire process, and use them to do a rockwell hardness test to make sure everything went OK.

marcF047
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Joined: Sun Feb 02, 2020 6:07 am

Re:

Postby marcF047 » Sun Feb 02, 2020 6:08 am

captain_john wrote:OK, I will bite on this one.

What is an "SO" state?

I know that you described it as soft Demenagement paris and pliable but, how do you get "SO" as a description?

Is this an ASTM term?

I am puzzled?

:? CJ

I’m a new member here and I think that this site is a very good one because there are many different subjects and various tips!


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