Which one would you use for the given criteria?

S

SurvivalDude

Joined
Dec 7, 2006
Messages
15
Hello,
I'm seeking expert opinions please.
I'm making a knife from tool steel and have several options available to me.

I have a few criteria, and some choices for you guys to make. I then have a few questions at the end as well.


The Criteria:
1. Good edge holding ability/Wear resistance.
2. Not easily cracked from -70 Celcius, to 55 Celcius (130F)

The Steel Types:
A6
http://www.cintool.com/catalog/air_hardening/A6.pdf

S1
http://www.cintool.com/catalog/Shock_resistant/S1.pdf
S7
http://www.cintool.com/catalog/Shock_resistant/S7.pdf

M2
http://www.cintool.com/catalog/High_Speed/M2.pdf

O1
http://www.cintool.com/catalog/Oil_Hardening/O1.pdf
L6
http://www.cintool.com/catalog/Oil_Hardening/L6.pdf

W2
http://www.cintool.com/catalog/Water_Hardening/W2.pdf


I've heard that most professional knife makers would use L6 on their own personal knives.


What effects do the following produce when added to steel? Do they increase toughness, wear resistance, corrosion?
Tungsten
Nickel
Manganese
Chromium (Corrosion resistance?)
Molybdenum
Vanadium
Silicon


Thanks for the help!
 
I seem to recall an article or story by Jim Hrisoulas (I think) regarding such a request. I am going from memory here since I could not find the article, so please feel free to correct me.

There were some guys working every winter up near the north pole. They were looking for custom knives that would not break in the intense cold. They had tried a number of steels and, to my recollection, a number of makers; all the blades broke or cracked before the end of the season. When they came to Jim, he recommended L6 and made a blade or two for the group. The blades performed perfectly throughout the winter and was the first steel that never failed the workers. It was a well written article and certainly convinced me of the merits of L6 in extreme environments.
 
Thanks for the replies.

I'm curious, what do you think he heat treated the L6 to?

I have a chart that shows O1's Tougnhess and Wear resistance intersecting at RC56.

I'm curious to know at which point L6's Toughness/Wear resistance intersect at.


What do you guys think??
Do any of you perhaps have a tempering chart similar to this one below?

http://www.navaching.com/forge/heattreat.html



Look at that first picture, that S1 stuff is no joke. I wonder how it would perform at -90 Celcius?


If you go down further you'll see the O1 temper graph. The author states that it's not accurate, however, I need an accurate one for L6 & maybe even S1 now.


Do you guys think S1 would do well at The North Pole?
Anybody have a temper chart for L6 and S1?

Thanks again for the help.
 
L6 peaks in toughness at 60 Rc. I hope that answers your question.
There's different kinds of "L6" out there; I wonder which one Jim Hrisoulas used?
 
ok jsut a thought would maybe cryo then temper be a good thing
seeing how cold the steel would be getting in the field could it be that its sorta like being cryoed and then untempered (brittle)
just thinking out loud
 
Butcher block: I agree. Cryo, then temper, and the cold service temperature
should not embrittle the knife.
 
I just emailed Jim to see what type of L6 he used and how he heat treated it. I also got his opinion on using S7 as a rough and tough material too.

I guess we'll see if he replies. I'm very interested to hear what a man with his experience level will tell me!


I'll keep you guys posted. But please, continue discussion in this thread. ;-]

Regards
 
butcher_block said:
ok jsut a thought would maybe cryo then temper be a good thing
seeing how cold the steel would be getting in the field could it be that its sorta like being cryoed and then untempered (brittle)
just thinking out loud
Click to expand...


I remember reading a discussion somewhere where somebody was speculating (boy is that vague) that the reason steel tools break in extreme cold is because retained austenite is getting transformed to martensite, and of course it wouldn't be tempered, so it would be brittle. So you may be on the right track there.

Edited to add, I don't think L6 would have any RA, but I may be wrong.
 
Guys/Gals,

Dr. Hrisoulas has replied to my question. And it's as follows.


HEllo:

As far as the blades I did for the folks working up in Alaska and in the Yukon Territories...they were not L-6. I have no idea where that information came from, so please discount that... They were however welded elevator cable, XX Improved plow share (1080) steel hardened at 1600F into 425F nitre then oil quenched from 425 followed by a liquid N sub zero treatment. this gave a hardness of 57 Rc and were tougher than hell...

L-6 I do not feel would be able to give the performance that the welded cable did with all the lower carb "strands" from the welding processes on the individual wires.

If there is anything else I can help with by all means feel free to contact me..

JPH

Dr. J.P. Hrisoulas,
Metallographer, Bladesmith.
Author:
"The Complete Bladesmith"
"The Master Bladesmith"
"The Pattern Welded Blade"
http://www.atar.com



What does he mean by "xx"???
What is nitre??


Thanks!
 
I don't get it...

He heated the steel up to critical.
He then quenched it in 425F nitre (or bluing salt)
Then from 425 he quenched in oil to room temperature
Then cryo treatment..

A few things here throw my greenhorn knowledge for a loop....

I thought during hardening the temperature had to drop really quickly ...
How does salt make the temperature drop fast enough to get the steel hard?? Then why the heck would he use oil from 425F???
Then I noticed he used liquid nitrogen after it hit room temperature.
He never mentioned tempering at all.... does the cryo treatment make tempering unnecessary?? Wouldn't the blades still be at maximum hardness without tempering??


Thanks
 
- 70 C ?? You would certainly freeze your butt off even if the knife survived !! There is a Brittle Transition Temperature for steels and I have no idea what that might be for those steels . Nickel steels are often used for cold service so L6 might be a good choice .Otherwise I'd try A6 for better edge holding..
 
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