Temper more if steel is used in cold environment

[HDB]

Would it make sens to temper a knife/tool more if it's intended to be used, let's say, in the Arctic? The cold would make the steel more brittle so tempering at a higher temperature to increase tensile strength and toughness would make sense, wouldn't it?

[Frosty]

Yes it does make sense to draw a deeper temper for tools used in extreme cold. I've snapped rebar at -25f and one of the new guys at the service station, back in the day, waaayy back, put his hand through a trunk lid pushing a car into the bay. We were both new to the jobs when we did it and violated a rule. I violated the "NEVER use rebar as a hand hold in winter!" and the other guy violated the "Push on a corner!" rule.

So, yes steel does lose flexibility up to becoming brittle in extreme cold. I don't know if drawing a deeper temper would make a significant difference though but that would depend on the knife alloy too. I spent 20 years in the field as a field driller and never had a problem with a knife, even my old 1960's Buck sheath knife and those are brittle out of the box.

I think how it's used is more significant, if a person is prone to use a knife like a pry bar like Primitive Pete (Old shop class safety movie character) they're going to break and ruin blades no matter what the maker does. Just do NOT put pressure sideways on the blade is your best defense against breaking them.

On the other claw, drawing a little deeper temper won't hurt if you can accept the softer edge or can do so in a progressive temper. I suppose it's a "can't hurt much, might help situation."

I'll be really interested in seeing what other folk say. It's a good question, good thinking.

Frosty The Lucky.

[Charles R. Stevens]

Are you talking about me, Frosy?! ;-)

[Frosty]

Are you talking about me, Frosy?! ;-)

​Am I? do you remember "Primitive Pete?" I don't think a mere mortal would make it to their teens doing half what Primitive Pete did.

Frosty The Lucky.

[Charles R. Stevens]

Probbably not, but I have broken my share of knives. 

[Steve Sells]

Before you worry about heat treating for the extreme cold, you should always remember to choose the correct steel for the intended use. That solves many problems people have with knives.,  1095  vs 1075 is a serious thought to have in that case.

[Bo T]

I read up on this a couple of months ago. Nickel seems to be the alloy of choice for cold weather work. I don't know how workable it is but 15N20 seems to be a good choice for lower temperatures that most will be out in. Alloy seemed to be the first consideration followed by good grain refinement and heat treat.

Edited March 25, 2015 by Bo T
I typed in chromium instead of nickel the first time.

[easilyconfused]

Before you worry about heat treating for the extreme cold, you should always remember to choose the correct steel for the intended use. That solves many problems people have with knives.,  1095  vs 1075 is a serious thought to have in that case.

​I agree. The steel has as much of an impact as the temper when it comes to the impact of environmental temperature and brittleness.  

[HDB]

I've done a bit of research.

Ferritic and martensitic steels tend to become more brittle the colder it gets. You can temper the steel more to make it more suitable to the cold, but this works only to a small degree. 

The clue to cold "proof" steels is the Face Centered Cubic structure of steel: Austenite. Steels in their austenite form are both tough and strong in very cold (~arctic) conditions. They aren't affected to cold the way 'classic' ferritic/martensitic steels are.

Is this due to the nickel content? Yes, indirectly. Nickel is an austenite-stabilizing element,  but so is manganese. So both Nickel and Manganese are important.

Sources:

• http://www.bssa.org.uk/topics.php?article=41
• ASM - Metals HandBook VOL 4

 

[Bo T]

That is a good link. One area that I couldn't find much information on was the transition temperature vs hardness for given steels. My guess, based upon the little information that I could find was that 15N20 could work down to @‌ -40 or -50 C. Perhaps the best bet is to use 2 knives, a soft one for outside and a hard one for inside.

[MrMaelstrom]

I used to go winter camping quite a bit, and got started making tomahawks around the same time. Brought my first one out with me and promptly chipped the edge later that evening. It was about 0 F out as I recall. It wasn't known steel, and my heat treating wasn't as good as it is today, but the image of my pride and joy ( at that time) chipped to XXXX stuck with me 

Since then I make my winter axes out of 4140. They don't hold an edge as well, but I have no complains taking it to a stone a bit more instead of trying to grind a chip out. 

 

Just my two cents.

[Charles R. Stevens]

For the scrap hounds, rail steel, 85-95 point manganese steel (depending on the information source) just think of its original use. What other things live in those environments? Snowmobile and other vehicle springs...