Hello everyone, and especially any of our smiths here. If a blade has been tempered and then is exposed to extreme cold, negative degrees Fahrenheit, can the blade become brittle and require re-tempering to prevent this? Just curious and thought to ask here.

I live in Finland. It gets fairly chilly up here now and then. I've dabbled with swords and such for a couple of decades, and have used camping and woodworking tools my whole life; when I was in the army, we actually happened to camp out in the record lowest temperature ever recorded in the country, -51.5 C (my, what fun).

I've never seen this happen to any sword, knife, saw, axe, other metal tool or even any gun, although some firearms with tight tolerances can get unreliable in extreme cold, especially if the lubricant isn't designed for those kind of conditions.

I suppose quenching a blade in a supercooled liquid as part of the heat treatment might have some kind of effect, for better or worse, but I don't think naturally occurring ambient temperatures can cause any kind of structural alterations to the steel.

There can be slight shrinkage which can cause problems with moving parts, e.g. for tightly fitted scabbards with or without metal throats (or firearms), and sharp differences in temperature can cause temporary warping which might create or aggravate internal tensions in the steel, but I've never personally suffered nor witnessed that issue. You can also run into problems with condensation and subsequent rust in unexpected places - if you've been using a sword out in the cold, after you bring it back in always make sure to let it sit in the open out of the scabbard for a while and then wipe it down thoroughly (axes and such... meh, they'll survive). Plus, real cold makes you clumsy and accident-prone, even aside from having to wear thicker clothing - you lose some sensation in your fingers, your muscles get stiff and shaky, your patience gets worn down by the constant low-level aching, and so on. All in all, I would not be surprised to find out things break more often in the cold, but don't think it's because of any structural changes in the metal.

And also, kids, don't ever touch sub-zero metal with any patch of bare skin you'd like to keep! :)

I think cold can have a range of effects but as mikko says not directly relating to making steel brittle. Otherwise the military and commerical shipping would not be able to function in extreme cold. Think tanks, ships, icebreakers, all those metal sheets, gun barrels, communications and delicate structures in arctic winds.

:eek: So, Timo, you're telling us that in extreme cold conditions, we should be careful about parrying with our SHIPS...

I vaguely recall an account where the writer complained about wootz not performing well in cold weather.

I know a couple of HEMA groups who train exclusively outdoors up in Sweden and Finland, who say that when it gets into winter proper you have to stop using steel feders or you'll break too many.

SO what I am getting is that exposure for a few days and not being used should not mean that the blade has to be re-tempered because it may have become brittle from being in the forge to be finished?

[quote="Timo Nieminen"]

Karl G wrote:

Ships have failed due to brittleness from cold: [ Linked Image ] For equipment that will be used in very cold conditions, it becomes important to choose an alloy that isn't too brittle at those low temperatures. If the wrong alloys are used, something like the above can happen. https://en.wikipedia.org/wiki/Liberty_ship#Hull_cracks

The pertinant part of the article as it relates to the discussion
"Furthermore, the ships were frequently grossly overloaded, increasing stresses, and some of the problems occurred during or after severe storms at sea that would have placed any ship at risk"

In other words, yes when you have thousands of tonnes strain, extreme leverage ,torque, movement, long relatively thin monolithic sheets of of steel are bound to have problems.

But I think you would be hard pressed to find any of the superstructure, hand rails, vanes, lifeboat racks, window frames or door knobs breaking off in the cold.

Scott I think you will be fine. Disregarding some of the less relevant examples, apply some common sense here. Does the superstructure tend to break off antarctic vessels and remote weather stations from cold exposure? Are they replacing their struts, com towers, external fittings, anchor chains, cranes, derrick arms, deck machinery every week due to steel failing from cold alone?

Thank you for the replies and reaffirming my suspicions to everyone that replied.

[quote="Timo Nieminen"]

Karl G wrote:

"Brittle" doesn't mean things break automatically. The glass windows in my house are brittle, and they survive many years. From the graphs in the link I posted above, it looks like steels like mild steel below -50C become at least as brittle as hardened and tempered high carbon steel (at room temperature), maybe even as brittle as hardened and tempered high carbon stainless steels like 440C. That's much more brittle.

I dont disagree with the article. And agree facts beat anecdotes but only insofar as they can be interpreted to match reality.

The author of the article obviously has some scientific expertise, and is providing information regarding a statement or problem, the issue of "cold shortness". However as an enginner would say whether it effects a sword practically at these temps is still up in the air.

Someone needs to leave a sword -50 and then put it through some hits :)