Why don't we have lightweight steel carabiners?

As far as I'm aware there are steels with better strength to weight ratios than 7000 series aluminium so why don't we use them? If we can make a 19g fully rated biner surely a steel biner could be even lighter.

What steels are you talking about? As a general rule, steel is more dense than aluminum, which translates to heavier biners. You might argue that we could use less material, but that would likely mean smaller and/or more narrow biners, which probably wouldn't be ideal. You also need to consider the material properties- maybe there is a strong, lightweight steel alloy out there, but does it exhibit the energy absorption properties we need for this application? What if it's incredibly brittle? Probably not suited to climbing, where it might face repeated impacts against a hard surface.

I dunno, I'm just spit-balling here. Without more information about the steels you're referring to, you can't really say anything conclusively.

Finn the Human wrote:

You also need to consider the material properties- maybe there is a strong, lightweight steel alloy out there, but does it exhibit the energy absorption properties we need for this application?

Your aluminum biners are not absorbing any energy.

 What if it's incredibly brittle? Probably not suited to climbing, where it might face repeated impacts against a hard surface.

Not the same thing.

We need to go titanium :)

Why don't we have lightweight steel airplanes?

Finn the Human wrote:

What steels are you talking about? As a general rule, steel is more dense than aluminum, which translates to heavier biners. You might argue that we could use less material, but that would likely mean smaller and/or more narrow biners, which probably wouldn't be ideal. You also need to consider the material properties- maybe there is a strong, lightweight steel alloy out there, but does it exhibit the energy absorption properties we need for this application? What if it's incredibly brittle? Probably not suited to climbing, where it might face repeated impacts against a hard surface.

I dunno, I'm just spit-balling here. Without more information about the steels you're referring to, you can't really say anything conclusively.

Standard chromoly steel has almost twice the tensile strength a Ali, we are already making smaller and finer carabiners so making a all wire biner isn't exactly unreasonable just make the load bearing surface a bit more rope friendly. 

Dave Kos wrote:

Why don't we have lightweight steel airplanes?

Carabiners are not even remotely similar to airplanes, the forces are completely different as are the material they use.

Which steels are you talking about? Looking at the wikipedia article, I can't find any steels with a higher specific strength.

https://en.wikipedia.org/wiki/Specific_strength

https://en.wikipedia.org/wiki/High-strength_low-alloy_steel

Assuming there's a steel with specific strength that's higher than aluminum, then yes you potentially could make a carabiner smaller and lighter. Downsides though include cost (exotic steel vs common 7075) and corrosion resistance (steel can rust). 

Marc801 C wrote:

Your aluminum biners are not absorbing any energy.

I was referring to the area under the stress-strain curve, which is indeed a measure of energy absorption (i.e.: toughness). Your biners do absorb energy when loaded, and then release that energy when unloaded. Ideally, you won't be loading a biner outside of its elastic range, but, given the choice, you certainly want a tough, ductile material over a brittle (likely less tough) one.

The point I was trying to make is that ultimate strength is not the end-all-be-all. Material response and expected loading conditions play just as large of a role when deciding what material to use for a given application.

Not the same thing.

Not sure what you're referring to here.

Finn the Human wrote:

Not sure what you're referring to here.

Your clarification answers it.

It would not be hard to make a very small steel carbiner with comparable strength to that of aluminum, perhaps even better.  It just wouldn't be very useful because it'd be tiny.

Aluminum is great because it is less dense and allows us to make things bigger without making them heavier.  

Perhaps the conversation will move on to a discussion of stiffness, moment of inertia, and other such things, but making them big is really the gist of it. 

You see aluminum, composites, titanium, and magnesium where the design is stiffness driven and weight matters.  You want something big that isn't floppy.  

Titanium carabiners are not unheard of, especially in Russia.  The ones I've seen have been quite a bit heavier than aluminum and a touch smaller.  

Perhaps one day we will have big carbon fiber snap links of some kind as it has even better stiffness to weight properties.  Who knows? 

I'm more interested in seeing Metolius make the biner described in this patent they have: https://patentscope.wipo.int/search/en/detail.jsf?docId=WO2014107417

TL;DR is an aluminum biner with a steel insert on the main wear surface.

This is the first trolling post I have found entertaining. 

Titanium !   Without doing any research but I'm guessing it would cost 5x without much weight advantage.

Rust

Jay J wrote:

...

carbon fiber snap links  

this would be interesting r&d

John W. and John B.: Yes! I'm stoked it's a thing now.

John Badila wrote:

Seems like a solution for permadraws that see a lot of wear, but then again weight doesn't really matter there, so not sure what it buys you over an all steel biner?  Maybe cost?  It didn't show any prices, so I have no idea if it would be cheaper. 

Stagg54 Taggart wrote:

Seems like a solution for permadraws that see a lot of wear, but then again weight doesn't really matter there, so not sure what it buys you over an all steel biner?  Maybe cost?  It didn't show any prices, so I have no idea if it would be cheaper. 

I was thinking of using them for toprope anchors, and maybe the locking version for my belay/rap device biner too.

Ronald B wrote:

I was thinking of using them for toprope anchors, and maybe the locking version for my belay/rap device biner too.

They are massively expensive, sorry to burst the bubble for these purposes you are much better off with a standard full steel biner.