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Scott Kowalski




Location: Oak Lawn, IL USA
Joined: 24 Nov 2006

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PostPosted: Thu 28 Feb, 2019 5:48 pm    Post subject: Question about steel and extreme cold.         Reply with quote

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.
Chris Landwehr 10/10/49-1/1/09 My Mom
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Glen A Cleeton




Location: Nipmuc USA
Joined: 21 Aug 2003

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PostPosted: Thu 28 Feb, 2019 8:24 pm    Post subject: Re: Question about steel and extreme cold.         Reply with quote

Scott Kowalski wrote:
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.


Welcome

I worked at sub zero (f) for several northern NH winters with axes and hand saws (from bow saws to two man felling saws and lots of axes). We never had a saw fail and those were thinner than most axes. They did need sharpening and even with significant age, they seemed hard and springy enough. One fellow fell in love with a double bit axe but went/filed too thin and too sharp. He came back in one day with a large chunk out of one edge from a frozen rotted log. Chided for my thicker convex and some blended bevel, I never lost an edge and my Plumb single bit (the last I retained from those years) from the 1960s is still as hard as it has ever been.

A couple of thoughts though. If expected to be used at those temperatures, store them colder than room temperature. They will cool off quick enough but I always felt cold storage was less shock than leaning next to the fire, then to ten below or so. We had some weeks that never went above zero (f).

There is also the "magic" some claim of cryo treating and the myths of cold storage improving hardness and toughness but again with forestry tools, I always felt cold storage suited cold work.

Some non-ferrous alloys don't do well at all when bitter cold.

It really isn't the blade but frozen stuff can break and chip fine edges.

Cheers
GC
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Mikko Kuusirati




Location: Finland
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PostPosted: Thu 28 Feb, 2019 11:24 pm    Post subject:         Reply with quote

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! Happy

The subtle tongue, the sophist guile, they fail when the broadswords sing;
Rush in and die, dogs -- I was a man before I was a king.
-- R. E. Howard, The Road of Kings
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Karl G




Location: Australia
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PostPosted: Fri 01 Mar, 2019 2:28 am    Post subject:         Reply with quote

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.
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Timo Nieminen




Location: Brisbane, Australia
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PostPosted: Fri 01 Mar, 2019 5:32 am    Post subject: Re: Question about steel and extreme cold.         Reply with quote

Scott Kowalski wrote:
If a blade has been tempered and then is exposed to extreme cold, negative degrees Fahrenheit, can the blade become brittle


Yes. This is called cold-shortness, and can be measured via the variation in fracture energy (Charpy impact energy, or Izod impact energy) with temperature. For low carbon steel with minimal impurities, the transition from ductile to brittle is at about -50C. Lots of phosphorus, and this will happen at higher (but still cold) temperatures.

High carbon steels - which will start off much more brittle than low carbon steels at room temperature - have a much smaller increase in brittleness (i.e., reduction in fracture energy).

Some further info: https://www.tf.uni-kiel.de/matwis/amat/iss/kap_9/illustr/s9_1_1.html

Scott Kowalski wrote:
and require re-tempering to prevent this? Just curious and thought to ask here.


It's only brittle while it's cold. Just let it warm back up, and it's fine.

"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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Timo Nieminen




Location: Brisbane, Australia
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PostPosted: Fri 01 Mar, 2019 5:36 am    Post subject:         Reply with quote

Karl G wrote:
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.


Ships have failed due to brittleness from cold:


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

"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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Matthew Amt




Location: Laurel, MD, USA
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PostPosted: Fri 01 Mar, 2019 5:53 am    Post subject:         Reply with quote

Eek! So, Timo, you're telling us that in extreme cold conditions, we should be careful about parrying with our SHIPS...
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Dan Howard




Location: Maitland, NSW, Australia
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PostPosted: Fri 01 Mar, 2019 6:14 am    Post subject:         Reply with quote

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




Location: Nipmuc USA
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PostPosted: Fri 01 Mar, 2019 7:59 am    Post subject:         Reply with quote

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


Always with a strake, never keel to keel Wink
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T. Kew




Location: Cambridge, UK
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PostPosted: Fri 01 Mar, 2019 10:08 am    Post subject:         Reply with quote

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.
Instructor and scholar, Cambridge HEMA
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Peter Lyon
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Location: New Zealand
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PostPosted: Fri 01 Mar, 2019 10:34 am    Post subject:         Reply with quote

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


That may have been Kindi in his treatise "On swords and their kinds". I recall reading the same thing somewhere, a clear warning that crucible steels became brittle when cold.

Still hammering away
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Pieter B.





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PostPosted: Fri 01 Mar, 2019 11:37 am    Post subject:         Reply with quote

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


Its from a 10th or 11th century writer from what is now Persia/Afghanistan. He noted that the Rus don't use Hindustan swords because they break in the cold so instead they create patterns by mixing hard and soft steel (i.e. pattern welded blades).
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Scott Kowalski




Location: Oak Lawn, IL USA
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PostPosted: Fri 01 Mar, 2019 4:49 pm    Post subject:         Reply with quote

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?
Chris Landwehr 10/10/49-1/1/09 My Mom
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Karl G




Location: Australia
Joined: 25 Apr 2016

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PostPosted: Fri 01 Mar, 2019 5:12 pm    Post subject:         Reply with quote

[quote="Timo Nieminen"]
Karl G wrote:


Ships have failed due to brittleness from cold:


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?
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Mikko Kuusirati




Location: Finland
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PostPosted: Sat 02 Mar, 2019 9:08 am    Post subject:         Reply with quote

Timo Nieminen wrote:
Yes. This is called cold-shortness, and can be measured via the variation in fracture energy (Charpy impact energy, or Izod impact energy) with temperature. For low carbon steel with minimal impurities, the transition from ductile to brittle is at about -50C. Lots of phosphorus, and this will happen at higher (but still cold) temperatures.

High carbon steels - which will start off much more brittle than low carbon steels at room temperature - have a much smaller increase in brittleness (i.e., reduction in fracture energy).

Some further info: https://www.tf.uni-kiel.de/matwis/amat/iss/kap_9/illustr/s9_1_1.html

Actual data beats anecdotes. Flawless victory. Happy

Scott Kowalski wrote:
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?

Yeah. Ambient temperature can increase the brittleness of materials, but the effect is temporary and doesn't affect the internal structure of steel like heating and quenching does, so no re-tempering is needed; it's just more brittle while at -20C than at room temperature, is all.

Glen A Cleeton wrote:
Matthew Amt wrote:
Eek! So, Timo, you're telling us that in extreme cold conditions, we should be careful about parrying with our SHIPS...


Always with a strake, never keel to keel Wink

And preferably not across the waves...

The subtle tongue, the sophist guile, they fail when the broadswords sing;
Rush in and die, dogs -- I was a man before I was a king.
-- R. E. Howard, The Road of Kings
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Scott Kowalski




Location: Oak Lawn, IL USA
Joined: 24 Nov 2006

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PostPosted: Sat 02 Mar, 2019 10:45 am    Post subject:         Reply with quote

Thank you for the replies and reaffirming my suspicions to everyone that replied.
Chris Landwehr 10/10/49-1/1/09 My Mom
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Harry Marinakis




PostPosted: Sat 02 Mar, 2019 9:56 pm    Post subject:         Reply with quote

Mikko Kuusirati wrote:
...we actually happened to camp out in the record lowest temperature ever recorded in the country, -51.5 C (my, what fun).


I spent a month camping at -37 C.

I can't imagine what -51 C was like!

Firesteel Designs
Hand-crafted good lovingly infused with hemoglobin
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Timo Nieminen




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PostPosted: Sun 03 Mar, 2019 2:32 pm    Post subject:         Reply with quote

Karl G wrote:
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?


"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 don't recommend using swords that are as brittle as hardened and tempered 440C.

If somebody has measured the increase in brittleness for the alloy used for the sword(s) in question, with similar heat treatment, and the brittleness at the temperature of interest isn't too high, then one might happily go ahead and use the sword(s). Without such data, the safer option is to treat the steel as too brittle to cope with the kind of impact swords potentially face, if the temperature drops too low. How low? Perhaps -20C for high carbon steel which shows embrittlement well before the transition temperature for pure iron and low carbon steel.

The simple solution: wait for warmer weather, or train indoors in a heated room.

"In addition to being efficient, all pole arms were quite nice to look at." - Cherney Berg, A hideous history of weapons, Collier 1963.
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Karl G




Location: Australia
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PostPosted: Tue 05 Mar, 2019 11:03 pm    Post subject:         Reply with quote

[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 Happy
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T. Kew




Location: Cambridge, UK
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PostPosted: Wed 06 Mar, 2019 11:05 am    Post subject:         Reply with quote

Karl G wrote:

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 :)


Fortunately, the Swedish HEMA folks have done this test for us. The ones I've spoken to say that at significantly sub-zero temps you tend to break disproportionately many steel swords. So they use plastic simulators instead when the temperature drops below 0.

Instructor and scholar, Cambridge HEMA
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