Aluminum question.

[High Scale]

I have been told in the past that dropping Aluminum Karabiners as long as the gate is not damaged makes them stronger.

 

It has something to do with the molecular structure being changed with repeated blows.

 

True or false?

[Mesterh]

I heard that old Karabs are strong than new ones and that dropping them doesnt do any damage, well as long as there is no external damage.

Not sure if dropping them makes them stronger though.

[walker]

I do a little blacksmithing and we call the repeted process of hitting steel at room tempreture work hardening. So perhaps the same is true of aluminium? Im not to sure how it would react to repeated droping. Metal fatiuge could happen and weaken the Karabiner.

 

Joe

[bob]

rather you than me

they are strong enough for what i want

and cheap enough to replace

although i would have thought if it made em stronger they would have done it at manufacture

but NO i do not know a definative answer

[Treewolf]

Not a good idea. If they work harden, which is possible through repeated moderate impact, they will become more brittle.

 

The ultimate tensile strength might possibly increase but the failure mode will change from a ductile failure (when you will get some warning) to a brittle failure (when you won't). Furthemore any nicks or dents might lead to the stress cracks forming and fatigue failure following crack propogation.

 

I used to pothole a great deal a good few years ago and it was a cardinal sin to drop ANY climbing hardware. Any krabs etc which were accidentally dropped would either be intentionally destroyed so they couldn't be used again, or marked for tackle-hauling only.

 

Don't do it.

[detritus21]

Aluminium does work harden and become brittle. Best thing is not to drop the stuff too hard or often.

[Log-ologist]

Hammering metal is a clever way of changing its crystaline properties.

 

Pro tip.

 

Broken starter spring , no spare.

 

take appart remove spring. take the broken end ( usually outer coil where it loops onto the casing) hammer it sharply several times using the truck tow ball as an anvil. Gently bend the end round with pliers to make a new loop. Beginners may take several attempts to achieve good results.

replace spring , finish job , buy new spring on way home.

 

Why does this work.?

 

hammering the spring steel changes the crystalline structure of the steel, the hammered bit just forgets its not a spring and will bend to a new position.

[Treewolf]

What happens when you hammer a metal it depends whether it is a material that work hardens. Do that with aluminium and it will break unless you anneal it.

 

With some materials hammering can stress-relieve them, but aluminium isn't one of them.

[Log-ologist]

I must add that I prefer not to drop any equipment. Including 200T's from trees LW! ( you know who you are )

[Khriss]

I have been told in the past that dropping Aluminum Karabiners as long as the gate is not damaged makes them stronger.

 

It has something to do with the molecular structure being changed with repeated blows.

 

True or false?

 

Nah-absolutely false- aluminium work-hardens ie-gets stiffer but more brittle. Try it with a peice of ally sheet, bash it with a hammer repeatedly-itll get stiffer n snap.

 

K