6061 Aluminum T6511 temper: 5/16" dia rod: Hook bending?

[Ingenuity]

I need to make a few new sliding latches (no load applied to pin) from 5/16"Φ aluminum round stock and bend a 90° hook at one end (around a 1"Φ pin).

I can get some inexpensive 36" long stock from Amazon in 6061 Al T6511 temper. Would this material be suitable for such a bend?

 

[EdStainless]

It may not work, according to Alcoa the alloy has low formability in that condition.

http://www.astro.caltech.edu/sedm/_downloads/Extruded_Alloy_6061.pdf

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P.E. Metallurgy, Plymouth Tube

 

[btrueblood]

What Ed said - the bar is likely to crack if you bend it to that shape. You can anneal it to get slightly better formability, or heat it to the forging temperature for that alloy (750-900 F from memory, but you might want to google and find the full data sheet with heat treatment info) and hot bend it. Of course, you then won't have the same tensile strength in the final hook that the original material had. You could then solution anneal it, and re-age to recover the -t6 temper, but the material may have much coarser grains after all that heating and bending and reheating, and as such not have the corrosion resistance and fatigue strength that the original material had. You might not care about that given you have "no load applied" (in which case why does an air latch not work? - if so, google the term "annealing 6061 aluminum" and get any number of ways to do so.

 

[Ingenuity]

EdStainless and btrueblood,

Many thanks for the reply.

I purchased the product (less than $25) and will give it a trial. I shall report back with my results, and if I need to anneal it after my first trial.

Thank you.

 

[WKTaylor]

Ingenuity...

Red-rust on the Latch-pin in the photo implies the pin shown is steel, probably ~Ftu ~60-KSI.

Typically I would disposition to form the Latch-Pin in the -T4 temper [bend radius TBD]; then Age harden to -T6 per any valid aluminum alloy heat treat spec, [AMS, MIL, ASTM]. This does (2) important things: improved ductility in -T4 temper makes the part easier to form to a tighter bend radius without threat of cracks or significant Ludder's lines; and the long Aging HT is a great stress relief operation.

Why Do you really want to make the pin from aluminum?? What I am most concerned about is what You intend to use the pin for: 'sliding latch'. IF in constant use, then the pin could wear-out rapidly. IF relied on for security, then it could be more easily damaged by a vandal/burglar.

You can probably find a steel 'rifle-bolt' or pre-bent Latch Pin [5/16-Dia] at a hardware store for much less than You think... and the steel would already have a tapered tip and zinc plating.



Regards, Wil Taylor

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[tbuelna]

From the photo provided, it looks like the bend is closer to a 1" radius rather than a 1" diameter. Consider using 6061 rod in an annealed condition for the forming operation, and then heat treat it after forming if higher strength is required.

 

[Ingenuity]

UPDATE: ==> I successfully cold-bent the 5/16"Φ alum rod around a 1-1/2"Φ pin. No visible detrimental effects.

Thank you for your comments/input.

 

[KENAT]

So you bend radius was close to 2.5T, which is probably around about the minimum bend radius for 6061-T6 at 5/16 thickness - or at least for .19 sheet metal I've seen recommendations of .38 min bend radii which roughly tracks.

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