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DPS

SS crampons vs aluminum (Dane ?)

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Much has been made about the susceptibility of stainless steel crampons to develop cracks or fail in one way or another yet I have not heard the same claims made against aluminum crampons.

 

Is this because folks who use aluminum crampons realize the limitations of aluminum crampons and use them for mostly approaches to alpine rock climbs and ski mountaineering and such or is the ductility of aluminum inherently less like to form cracks or fail catastrophically?

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I'm not a metallurgist and I've never broken a set of crampons, ss or otherwise. Still I feel like weighing in on this one.

 

If aluminum did crack like stainless steel there would be many reports of it happening in crampons. typically when I wear my aluminum 'pons it is with a pair of lightweight and very flexible set of boots, ss 'pons I wear with baturas or some old plastics I have that are totally rigid underfoot. Even with more flexible center bars on the aluminum campons I think this speaks for itself, there is a lot more repeated stress on lightweight crampons and they never break like the stainless ones. Micro fracturing in aluminum just does not happen.

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Don't know how I could bend AL pons when I walk like a little ballerina whenever getting onto dirt/rocks.

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I think it's just generally accepted that aluminum 'pons are for like you say short sections of easier hard snow and such, and not for something like vertical water ice.

 

I've been on hard ice with aluminum 'pons. It was on the descent of Dragontail at the top of the glacier, it was about 100 yards of 30 to 40 deg alpine ice. It was scary. I think it's because they flex so much that you don't get as good of a stick.

 

I think with really hard use, like on vertical ice, that if you tried to bend them they would bend. You just don't see that because people don't use them like that.

 

If you stay on neve you shouldn't have a problem

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I think with really hard use, like on vertical ice, that if you tried to bend them they would bend.

 

key word bend, not break.

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Finally broke my aluminum crampons this year, stepping down onto a rock. The connecting bar broke cleanly on either side of an adjustment hole. The field fix was easy. Just tied em together with some string. They were about 5-6 years old and I doubt they had much more than 30 to 40 4 or 5 mile trips on them, mostly on crusty snow. Got them welded at the shop our company uses and they broke again next time out, very near to the weld which made me think the heat of the weld somehow weakened the Al. Meanwhile Camp had sent me steel connecting bars, saying thats what they recommend in conjunction with the lightweight boots I normally use (Asolo Stynger). They thought it was the flexing that broke the bar. This agrees with my recollection of stepping down onto what I thought was a flat rock and stumbling just a bit. When I got them I thought I would be busting the teeth off but over the years I have been rougher and rougher on them and I have had no other problems. I kinda doubt you could bend them - they just snap.

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The connecting bar is not where the sabertooths have been breaking, I can totally see what you're describing there, but are there any instances of aluminum crampons breaking under the ball of the foot? The bar broke due to metal fatigue, not microfractures. If you bend a part of the aluminum crampons they are liable to break if that part is repeatedly stressed.

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A friend of mine went into Snell Sports in Chamonix last summer thinking about getting a pair of lightweight Grivel Aluminium crampons, the salesman strongly advised him to get a pair of lightweight steel crampons instead because they had had quite a lot of returns of broken aluminium crampons.

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Got them welded at the shop our company uses and they broke again next time out, very near to the weld which made me think the heat of the weld somehow weakened the Al.

 

Can't weigh in on the stainless issue since I am not familiar with it and it would depend a lot on the type of stainless used (ferritic, martensitic, or austenitic) however welding aluminum has a huge impact on the strength. It varies by alloy and weld procedure, but the strength reduction can be as high as 50%.

 

Aluminum also does not have a fatigue limit like steel does. Fatigue limit is the stress which you can subject the material to an unlimited number of times without it fracturing. In the case of the aluminum connector bar and a flexible boot, you are stressing this piece with each step, and depending on the stress level there is a limited number of times this can be endured without breaking. Hence the steel connector recommendation. The stress induced is likely below the fatigue limit of steel and should last forever, or at least only slightly above requiring 10^reallybignumer cycles to failure. At which point you've worn the points off and recycled the pons anyway.

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Aluminum also does not have a fatigue limit like steel does.

 

I'd suspect that Dane knows more about metals than the rest of us combined, but till he shows up: I'd never really thought of it before. Aluminum definatly will work harden and break. Take a pop can and wiggle it back and forth a bit...you'll see. But there is a lot of Al configurations, as I'm sure some Boeing engineer will soon step up to describe for us:-) However, I suspect that the reason al. doesn't get the crap SS does for pons is cause the al tend to be made for non-technical stuff...ie, walking on glaciers. Thus, it tends to not be subjected to the same forces, and when it breaks, is generally on less technical (and less fatal) ground. I've heard of the al center bars breaking (often when stepping on rocks, but also just due to fatigue and age), but not the al front points falling off. I'd avoid al for front pointing too. Anyone have any thoughts?

 

hmmm, something new to consider.

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""Got them welded at the shop our company uses and they broke again next time out, very near to the weld which made me think the heat of the weld somehow weakened the Al.""

 

all aluminum used for climbing gear is hardened. When you weld aluminum the heat brings it back to it's dead soft condition, IOW unhardened.

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