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carabiner failure 29-Oct-2006 At 7:00:03 PM AlanD

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On 29/10/2006 Climboholic wrote:
>Also aluminium alloys have a limited fatigue life wheras steel has virtually
>no fatigue life. So if a crack nucleates in an al-alloy biner it is more
>likely to grow to the point of failure at loads beneath its yield strength
>than in a steel biner.

Not correct. Both aluminium and steel have a finite fatigue life. It really depends on the specific alloy of steel or aluminium, and also half a dozen other factors. The result of cyclic loading below the yield point will vary from no crack initiating, no crack propagating or failure of the metal.

In all honesty, I very much doubt that a biner will ever suffer from fatigue cracking, according to the proper definition of fatigue. It's more likely that a crack propagates when it experiences cyclic overloading.

>The advantage of Aluminium alloy is it's specific strength, ie strength to weight.

100% agree.