temper, and COLD weather question

SeanMK

Member
First off im a newbie to the whole knifemaking thing, but have been in the welding/welding sup. bus. for 21 years, so im not a complete idiot on metalworking and such.

BUT this subject was on a camping/survival page, and I am kind of puzzled.

The gist of the comment was "do you switch to stainless blades in cold weather, because carbon blades have a tendency to reverse temper in cold temps under 30 deg."

I am just baffled as I have never ever heard of a knife losing its temper or becoming harder because its too cold.

just curious if this has any truth to it, and if so, why/how does this exactly happen.
 
Hello Sean,
I am not a metallurgist, But this statement sound like absolute BS!! In all my study and knifemaking over the last 15 plus years and my life! I have never heard anything about a knife steel losing or gaining in hardness or temper in 30 degrees Fahrenheit weather, Stainless or Carbon??

Cryogenic Treatment of Steel is when they flood the chamber with Liquid Nitrogen and take it down to absolute zero which is 300 degrees below zero if I remember the process correctly? " Late and had some beers!"

This tightens the grain structure and then it is tempered again to take out the brittleness.
We are not talking about a cool evenings weather here.

Please don't beleive everything you read on those Survival sites!

Laurence

www.rhinoknives.com/
 
Oh no, I didnt actually believe it. actually the company i work for delivers Liq. N2 toa guy here in omaha that actually does cryo tempering. and A LOT of it.

Just wanted to make sure my ducks were in a row before calling B S. Thanks Sean
 
I think that someone took a little knowledge and made a wild jump to a wrong conclusion. The temper will not reverce. It was noted that steel plates in ships hulls could become more brittle from cold waters of the poles but that was structural steel not tool steel. Then there's the little issue that stainless steel by the nature of their complex alloys are more brittle than carbon steels.

The cryo treatment that your company's customer does is probably to trigger complex steels with low Mf points to convert retained austinite to martensite.

That post you read has a very high BS factor.

Doug
 
Does this line of reasoning make sense?

As the temperature of a material (except water) decreases it's density increases. As density increases hardness increases. I don't think the temperature changes being discussed here will effect the blade's hardness to a degree noticable without very fine instruments.
 
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