extreme temperature and knife performance

Runs With Scissors

Runs With Scissors

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Dec 3, 2000
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It's been asked before if extreme cold temps affect a knife blades ability to hold up. Right now I'm coming to believe that yes, it can.

I'm currently employed in the oilfields on the North Slope of Alaska. As I recall the numbers we are not permitted to use a manlift at 25 below zero, or perform any kind of lifting operations at 30 below zero. (crane, loader, etc.) The most frequently stated reason, is of course hydraulics. As a general rule a machine utilizing hydraulics will lose one percent of it's lifting capacity for every degree below zero the ambient temperature drops. But the second stated reason when questioned on the matter is ALWAYS metal fatigue.

I also saw an old sign announcing the recall of Chinese made Shackles, and pointing out the differences between Chinese Shackles and American manufactured shackles. It specifically mentioned that "the Chinese shackles were much more likely to break in extreme temperatures than the American made shackles" This wasn't stated by some flag wavin' Bubba sittin' on his front porch, this was stated by BP Exploration.

As a practical matter, I've learned the lower the temp drops there, the more EVERYTHING wants to break.

As a consequence I've come to believe that extreme cold temps affect our tools much more than I had previously realized.

What to do about it? not much that I can see. Maybe use our tools a bit more gently when it gets that cold. Me personally, I'm sticking to carbon steel most of the time, due to the fact that I've yet to see a stainless steel cable or shackle up there.

Just a thought I figured I'd relate.:o
 
hi Scissors,

When we had guys up in your area using FRN handles, we learned that at 40 below 0, the FRN handles became brittle enough to break if dropped on the ground.

G-10 was ok at extremely cold temps.

I'd really like to know if stainless is less effective that carbon steel at the very cold temperatures. What and Why.

sal
 
Extreme cold will do strange things to metal & other materials. I would ask an Old Timer what works & what does not work under extreme conditions. We are talking brutal cold here & a lot of materials give up the ghost. I think I read somewhere where even the Eskimos do not venture out at 30 below. Or was it 40 below?
 
chinese shackles also don't have the 4:1 safety factor

30 below, I thought it was bad when I was on rigs in the Gulf when it got in the low 30s with gale force winds, geez.
 
I've been in Alaska at 20 below and I swear I could feel my blood slowing down.

But I must confess that I love the dog sled races, especially the Iditirod.

sal
 
I was under the impression that the modulus of elasticity of materials lowers with with temperature - i.e. things affectively become more brittle.

A natural logrithimic proportionalty? Taking temperature into consideration in regards to both extremes (high as well as low).
 
Modulus of elasticity does not change . There is a 'brittle transition temperature' at which a steel goes from ductile to very brittle .The temperature is dependant on chemistry and may be as high as 70 F !!. There are special steels designed for low temperature service , many have large amounts of nickel...The problem is not 'fatigue strength' either.The brittle transition temperature was one of the steel problems that did in the Titanic.
 
My last hitch the windchill got to around 75 below (100 below in some ares, I'm told) . I came back into camp at 6 in the evening, slurped down all the hot fluids I could, ate a hot dinner, stood in a steaming shower for damn near a half hour...I still had chills when I fell asleep 10:30 that night. I used to think I was a tough guy.....:(


Hi Sal,
I've pretty much come to distrust all plastics during the winter season. The only knife handles I use are currently either titanium, or G-10. I wouldn't have a problem with micarta, but don't currently have any work knives with that handle material.

I'd be curious as to the effects on stainless also. I can tell you very loosely that my Douk Douk holds up to minor chips and dings better than my SAK, but that's about all I've learned. I'd love to see some actual research into the topic. (especially since I could personally benefit greatly from that knowledge):D
 
'brittle transition temperature' - so the material properties are or are not changing?

Or is this considered to be a material property?
 
I found this awhile back Buck seems to be the only? manufacturer that states they test their knives at extream temps.


Will my Buck knife and sheath survive in extremely cold climates?
We have tested our products in -48º C (-55º F) temperatures without significant embrittlement of the blade, handle, or sheath materials. If you experience temperatures in the minus range, try to keep your knife dry and free of ice, and be sure to keep the blade lubed.
Click to expand...


I often wonder if other companys like spyderco, Benchmade etc... have done any testing of their handles and blades.


Bors
 
Mete is right. All materials such as knife blades have a BTR. It is usually most noticed in welded structures where a crack initiates in the HAZ (heat affected zone) and propogates along the weld line. The most famous examples in engineering are the King Street bridge in Melbourne Australia and the early liberty ships. Since knife blades are heat treated then it can be expected that it may have a BTR in the range of temperatures experienced in Alaska. Since the heat treatment varies considerably between carbon steel and the different alloy steels I would expect that some would fail and some would not in the environment. Unfortunately, I doubt if there is much research on knife blades as such. But I expect that there would be a wealth of information and papers on the reliability and durability of materials used for machinery and pipelines in that environment. Some of that may be applicable to manufacturers such as Spyderco. Sal certainly is interested in learning more.

One way to tap into this source of information is to sponsor a final year student to base their thesis on the subject. Maybe one of the manufacturers could tie in with a local university to do some low cost research.
 
The BTR involves the material property of toughness and is measured with impact tests such as the Charpy test. It's very dramatic to do tests and watch the toughness go from ductile [much stretching and bending before breaking ] to brittle [not stretching or bending before breaking ] with reduction in temperature !!!
 
Appreciate the info.

I did a mild google search and read a few pages. Grain size, molecular model shapes (FCC, BCC, etc) - makes me wish I'd taken more materials courses.

Interesting stuff, though.
 
Runs With Scissors said:
I've pretty much come to distrust all plastics during the winter season. The only knife handles I use are currently either titanium, or G-10. I wouldn't have a problem with micarta, but don't currently have any work knives with that handle material.

:D
Click to expand...

G10 uses epoxy resin as a matrix. Micartas are usually based on epoxy or phenolic. These thermoset resins lose less of their properties at -40F than most thermoplastics such as standard grades of nylon. (There are some special Nylon grades that retain much more of their properties at -40F, but I doubt they are the grades that are made into knife handles.)

We have used epoxy and phenolic laminates for aircraft parts for years. The temp at 35,000 ft is about -65F. And the laminates function properly in flight.
I said all that to say that if G10 works for you, micarta should too.
 
-20 ain't cold up here it's just a winter day, and -30 ain't extreme cold it's just colder;) ;) ;) I'm often in the woods in these temp. actualy I love it at these temp. it's so calm but I never notice any effect on my blades...next time I go I'll do a couple of test that I will share with you guys...Cheers!!!
 
My Gransfors Small Forest axe seems to chip easily not something I would have expected after reading so many rave reviews. although I now realize that I have been using it in temperatures below -20 C. I never thought temperature could have such a large impact on steel. I'll have to use it in summer to see if it really is the low temperatures and not a flaw in the steel.
 
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