Valkman
Member
I meant to say "knives that you or others have made" but I was in a hurry. 
I'd really like to see knives made from a cold quench.
I'd really like to see knives made from a cold quench.
Knife steel vs heat treatment
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Gordon
Member
I'll ask my bud Larry Harley
rcmodel
Member in memoriam
O.K., I just tried it.
Found a rusty deck nail in the basement nail can.
Heat soaked to very bright Red Hot with a torch.
And dropped it in a can of ice water salt brine loaded to over salt saturation point.
1. It hissed.
1A. It formed rust scale slag on it.
2. Then I cleaned it off in clean water and bent it 90 degrees with a hammer in a vice.
3. Then I used the vice to finish bending it 180 degrees back on itself.
4. There was no indication of any hardening, either on the surface, or clear through.
5. There was no indication of any surface cracking you would find if it had been hardened in the slightest.
In other words, it is still a soft steel nail, and always will be a soft steel nail.
Unless I somehow add enough carbon to it to harden it.
At that point of red hot, it could be hardened in water, oil, salt brine, a snow bank, liquid Nitrogen, or any number of other things.
And it would break, not bend double.
But cold salt brine will not add carbon to soft low grade steel and transfer it into a high-carbon knife grade steel.
rc
Found a rusty deck nail in the basement nail can.
Heat soaked to very bright Red Hot with a torch.
And dropped it in a can of ice water salt brine loaded to over salt saturation point.
1. It hissed.
1A. It formed rust scale slag on it.
2. Then I cleaned it off in clean water and bent it 90 degrees with a hammer in a vice.
3. Then I used the vice to finish bending it 180 degrees back on itself.
4. There was no indication of any hardening, either on the surface, or clear through.
5. There was no indication of any surface cracking you would find if it had been hardened in the slightest.
In other words, it is still a soft steel nail, and always will be a soft steel nail.
Unless I somehow add enough carbon to it to harden it.
At that point of red hot, it could be hardened in water, oil, salt brine, a snow bank, liquid Nitrogen, or any number of other things.
And it would break, not bend double.
But cold salt brine will not add carbon to soft low grade steel and transfer it into a high-carbon knife grade steel.
rc
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You shouldn't be getting any more out of chilling your brine than room temp would. Also "salt" is not a good heat conductor on its own, but a brine is better than plain water (but Super Quench is best at that for hot steel). Lowering the freezing point shouldn't be relevant since you're not freezing the water and quenching in -2 degree C water is no different than 20.
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Ya know you're know by the company you keep!
rcmodel
Member in memoriam
My comparison was in post #7, you said even a common nail could be hardened in ice cold salt brine.
And I said it couldn't in post #18, Because there is not enough carbon in it to harden it.
So I tried it.
And I was right.
Rc
And I said it couldn't in post #18, Because there is not enough carbon in it to harden it.
So I tried it.
And I was right.
Rc
rcmodel
Member in memoriam
Yea.
Pretty sure I don't understand hardening and tempering after doing it for 50 years.
You show me how to harden a common nail, and I'll eat it.
Well, maybe not eat it.
But I will believe it when I actually see somebody do it.
rc
Pretty sure I don't understand hardening and tempering after doing it for 50 years.
You show me how to harden a common nail, and I'll eat it.
Well, maybe not eat it.
But I will believe it when I actually see somebody do it.
rc
I guess not but to be fair its been the last 50 while we have been shipping all our manufacturing and engineering over to china not 200 years ago when most farmersYea.
Pretty sure I don't understand hardening and tempering after doing it for 50 years.
You show me how to harden a common nail, and I'll eat it.
Well, maybe not eat it.
But I will believe it when I actually see somebody do it.
rc
could harden iron.
I just did a vid showing and demonstrating how to harden a coathanger which has less
carbon than most common nails ill get it uploaded tomorrow and just for you ill also do
one with nails, now you already said you wouldnt realy eat it but I would appreciate it
if you would admit you were wrong when you seen it.
would you like me to use a old burnt nail or something new of the shelf?
Grab something new since we'd be able to see the box for comparison.
Zeke/PA
Member
Heat treating is really an ever changing science that unfortunately cannot be duplicated to it's greatest extent in the home workshop!
Making a knife from a local piece of metal?
A mower blade is great and the "almost" completed knife can be heated red and quenched in used motor oil. Polish the blade and put it into a 500 degree oven till you see it turn to a dark straw color.
You can then immerse in water to STOP the "draw" .
O.K. for a personal knife but new steels and heat treatment methods are best left to the pros!
Making a knife from a local piece of metal?
A mower blade is great and the "almost" completed knife can be heated red and quenched in used motor oil. Polish the blade and put it into a 500 degree oven till you see it turn to a dark straw color.
You can then immerse in water to STOP the "draw" .
O.K. for a personal knife but new steels and heat treatment methods are best left to the pros!
Sam1911
Moderator Emeritus
Actually, a "home" knife maker can do a whole (WHOLE) lot better than that with simple tools and things you can build for very little money, and a little research into proper tempering temperatures. Starting with a semi-unknown steel like a mower blade may hold you back a little from best success, but that's not even necessary these days with good known steels available for cheap.
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Pete D.
Member
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video
I am awaiting the video after reading through this thread.
Very interested.
Question: what is the function of carbon in steel as a necessary ingredient in proper hardening (not the best question, sorry)? We normally consider "high" carbon steel as appropriate for hardening (0.60 - 1.0% C). Low carbon steel (0.05 -0.15% C) is not so considered.
As I understand it, the carbon diffuses through the iron and helps the formation of a desirable crystalline structure. So...what happens if there is less carbon available to diffuse? Seems to me that even heating the metal to orange or yellow still leaves the alloy with less carbon. What structure would be formed in that case?
Not at all sure that I have this right....
Pete
I am awaiting the video after reading through this thread.
Very interested.
Question: what is the function of carbon in steel as a necessary ingredient in proper hardening (not the best question, sorry)? We normally consider "high" carbon steel as appropriate for hardening (0.60 - 1.0% C). Low carbon steel (0.05 -0.15% C) is not so considered.
As I understand it, the carbon diffuses through the iron and helps the formation of a desirable crystalline structure. So...what happens if there is less carbon available to diffuse? Seems to me that even heating the metal to orange or yellow still leaves the alloy with less carbon. What structure would be formed in that case?
Not at all sure that I have this right....
Pete
See this
this
and this
Read the first 2/3 of this - http://www.gowelding.com/met/carbon.htm
Carbon fits into the spaces between the iron atoms and influences the crystal structure. It forms pearlite, which is composed of ferrite layered with iron carbide. Pearlite driven by the carbon content and changes the steel’s mechanical properties, especially the hardness, but it also determines whether you have face centered cubic or body centered cubic crystals. This all occurs based on how rapidly you cool the steel and too rapid cooling produces brittle Martensite.
this
and this
Read the first 2/3 of this - http://www.gowelding.com/met/carbon.htm
Carbon fits into the spaces between the iron atoms and influences the crystal structure. It forms pearlite, which is composed of ferrite layered with iron carbide. Pearlite driven by the carbon content and changes the steel’s mechanical properties, especially the hardness, but it also determines whether you have face centered cubic or body centered cubic crystals. This all occurs based on how rapidly you cool the steel and too rapid cooling produces brittle Martensite.
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Here is the vid demonstrating hardening of mild steel im not sure if it can be embedded.
https://www.youtube.com/watch?v=QQ051Zie8pk
Ill do something with nails over the weekend.
https://www.youtube.com/watch?v=QQ051Zie8pk
Ill do something with nails over the weekend.
rcmodel
Member in memoriam
So far, it's apparent your and my definition of 'hardening' steel are two different things.
If you do the same heat & quench cycle with carbon steel and try to bend it prior to drawing the temper?
It will be so hard it will snap like a piece of glass.
Your coat hanger is no where near knife blade hardness, and never will be without adding carbon to the steel somehow.
Try the same test again with 1/8" music wire or spring stock and see what happens.
rc
If you do the same heat & quench cycle with carbon steel and try to bend it prior to drawing the temper?
It will be so hard it will snap like a piece of glass.
Your coat hanger is no where near knife blade hardness, and never will be without adding carbon to the steel somehow.
Try the same test again with 1/8" music wire or spring stock and see what happens.
rc
yes I have done something similar with a high carbon sword blade and yes it shattered
but that is also what I was trying to get accross with sam earlier is that you use
different temp ranges to achieve different results with different steels.
you also use different quenchs
yes I can make a good suitable blade from mild steel in this fashion but I would
as I have mentioned here and in the vid want to get the steel to a yellow heat rather than just orange which is the best i could do with the propane torch and that was just for a demonstration that it was possible.
well I guess like I mentioned to that poster on youtube one of us has a bad dictionary.
As much as I would like to take credit for something different I got my
imformation from a 200 + yo blacksmithing manual and started doing it
more than 20 years ago im not just pulling stuff out of my rear to be difficult.
but that is also what I was trying to get accross with sam earlier is that you use
different temp ranges to achieve different results with different steels.
you also use different quenchs
yes I can make a good suitable blade from mild steel in this fashion but I would
as I have mentioned here and in the vid want to get the steel to a yellow heat rather than just orange which is the best i could do with the propane torch and that was just for a demonstration that it was possible.
well I guess like I mentioned to that poster on youtube one of us has a bad dictionary.
As much as I would like to take credit for something different I got my
imformation from a 200 + yo blacksmithing manual and started doing it
more than 20 years ago im not just pulling stuff out of my rear to be difficult.
It would be great if you can scan or post pics of the manual.
Also, well shot video. So many youtube videos are set up badly, but your camera position was about perfect (a higher angle might have given a better viewpoint).
Steel for wire hangers is 1006 or 1008 "traditionally". Those are low carbon steels (0.08-0.1 C%). You showed that a quench in brine produced some hardening. Have you tried the rockwell files to bracket the hardness?
Also, well shot video. So many youtube videos are set up badly, but your camera position was about perfect (a higher angle might have given a better viewpoint).
Steel for wire hangers is 1006 or 1008 "traditionally". Those are low carbon steels (0.08-0.1 C%). You showed that a quench in brine produced some hardening. Have you tried the rockwell files to bracket the hardness?
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Im looking for the text now it was pretty cool an old blacksmith telling how he visited another blacksmith and secreted seperate bags of salt into his quench
to make it look all mysterious and keep his "super secret formula" later when he returned to the blacksmith who used what was left of the quench he had lots of return fix up work that came about because he relied to heavily on the formula thinking it magical and hence failed in his blacksmithing skills.
No ive done nothing with trying to define its hardness
I did check in a book I have about wrought iron and it lists the carbon content
of many samples of wrought iron which varied from about .02 to .06 so in every likely hood the carbon is important as others have suggested.
to make it look all mysterious and keep his "super secret formula" later when he returned to the blacksmith who used what was left of the quench he had lots of return fix up work that came about because he relied to heavily on the formula thinking it magical and hence failed in his blacksmithing skills.
No ive done nothing with trying to define its hardness
I did check in a book I have about wrought iron and it lists the carbon content
of many samples of wrought iron which varied from about .02 to .06 so in every likely hood the carbon is important as others have suggested.
rcmodel
Member in memoriam
Wrought iron cannot be hardened or tempered either.
Suggest you read this.
https://en.m.wikipedia.org/wiki/Carbon_steel
Skilled blacksmiths have been able to make high grade steel out of iron for many century's.
But none of then could harden wrought iron, or low carbon steel without pounding the impurities out of it and adding carbon from the charcoal fire in the forge.
rc
Suggest you read this.
https://en.m.wikipedia.org/wiki/Carbon_steel
Skilled blacksmiths have been able to make high grade steel out of iron for many century's.
But none of then could harden wrought iron, or low carbon steel without pounding the impurities out of it and adding carbon from the charcoal fire in the forge.
rc
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http://machinedesign.com/basics-design/crystal-structure
The discussion is about 1020, but I'd expect the same general concept to apply with the lower carbon 1006.
The discussion is about 1020, but I'd expect the same general concept to apply with the lower carbon 1006.
Zeke/PA
Member
Been there, done that!
Most mower blades are of a steel in the 1095 range heat treated to about 50 to 55 Rc.
The blades do in fact make into decent knives especially if one can forge and create a damacus effect.
I made a ton of knives in the past and truthfully, a piece of O-1 flat ground stock is a great start.
From a section of 4x 18 I could get 6 sheath style knives!
Most mower blades are of a steel in the 1095 range heat treated to about 50 to 55 Rc.
The blades do in fact make into decent knives especially if one can forge and create a damacus effect.
I made a ton of knives in the past and truthfully, a piece of O-1 flat ground stock is a great start.
From a section of 4x 18 I could get 6 sheath style knives!
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