Hardening low carbon steel

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I have been tripping over various articles, and websites recently that promise formulas for hardening low carbon steel. One was a rural/survival magazine, and another was a come on at some kind of metal or tool site. I was cruising on both occasions, and didn't have the time to follow up. Haven't been able to scare up the same web search, and that mag isn't in the stores any more.

My question is whether anything new is happening, where a different approach to hardening steel is allowing one to get adaquate results with lower carbon steels. How low are we talking (I thought CR was mentioned in one case)? What is the drill? Might be useful for some tooling if nothing else.
 
Maybe they were talking about case hardening the steel. That makes for a hard surface, but leaves the inside soft.:confused:
 
Mike Hull said:
Maybe they were talking about case hardening the steel. That makes for a hard surface, but leaves the inside soft.:confused:
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I agree with Mike

but I'll say you'll get less than adaquate results for knives.
 
One of the formulas you may have read about is one that has been talked about for ages in the forging circles. It is commonly called Super Quench.

Ingredients:

Quench at 1550 F (light cherry red)
Allegedly you can expect Rockwell C of 43 to 45 on 1018 mild steel. Some have supposedly gotten very good results using this quench for railroad spike knives.

I don't know. I'm just passing on the information. When it comes to mild steel for a cutting tool, I've always had one question -- "Why"?
 
I think some low C alloys with Nitrogen and Vanadium added are hardenable. I am not sure how good they may be for knives. Search VCN (Vanadium CarboNitride) complexes. There are tool steels being made with very low overall C content with these chemistries.
 
Thanks, Superquench is probably what I was looking for. I figured that might be it. I have a formula for that, but it was in the context of 1040 which is hardly a tough test, and therefore doesn't rule in lower C steels.

I wasn't particularly thinking of a knife, I just know there are a lot of folks here with good HT knowledge.
 
1040 and 1045 are used for low cost gears and are flame or induction hardened.The original structure would be mixed grains of ferrite and pearlite .In hardening the ferrite stays as ferrite but the pearlite grains transform to martensite.Lower carbon than that wouldn't be successfull.The other option is to case harden by adding things like carbon to the surface. Then you would get a martensite layer on the outside but a soft center.I'm not familiar with super quench so can't comment.
 
:) for knives I agree with Terry WHY
workable first and formost and looks later.. :)
I don't understand why guys want to use low C for knife blades?
if you forge and want to use low Carbon such as RR spikes,,,why not
just forge a High carbon edge on. :confused:
 
ive been thinking about a possible case hardened sword for a while now. my grandfather told me that they dont use arsenic anymore( i think it was arsenic), instead they bake the steel in carbon filled box and let it absorb carbon. could a piece of mild steel be soaked long enough in carbon to make it HT able? it would basically be iron or mild steel cored because the carbon couldnt penetrate that deep, but the out side would be like what 1050?1095? if so that would make a blade much like a japanese sword wouldnt it? soft inside hard outside, right? you could probly even put a hamon on it. this is just a theory, i dont have any expirience with case hardened steel.
 
Dan Gray said:
:) for knives I agree with Terry WHY
workable first and formost and looks later.. :)
I don't understand why guys want to use low C for knife blades?
if you forge and want to use low Carbon such as RR spikes,,,why not
just forge a High carbon edge on. :confused:
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I think it is because much of the custom blade business has forgotten what knives are for- cutting things! They are not prybars, cold chisels or masonry tool- they are knives. Face it, if we really need to worry about breaking a properly heat treated high carbon blade (that will hold a proper edge), we are doing something wrong and should probably go for another tool for the job.
 
You've got your poisons mixed up !! One of the case hardening methods is to use cyanide salts which add carbon and nitrogen to the surface .It would be difficult to control case hardening on a blade , you would very easily get very high carbon on the cutting edge.
 
Kevin R. Cashen said:
I think it is because much of the custom blade business has forgotten what knives are for- cutting things! They are not prybars, cold chisels or masonry tool- they are knives. Face it, if we really need to worry about breaking a properly heat treated high carbon blade (that will hold a proper edge), we are doing something wrong and should probably go for another tool for the job.
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Amen. I agree.
 
elevenbladesmith07 , case hardening is a surface treatment done as a final process.It is not to create some other steel.If you case hardened a sword,with ferric cyanide (not arsenic), it would be the last process done to the blade.Sharpening the sword would remove the case,or hard skin.You could not HT or put a hamon on a case hardened piece of metal.
Again,my advise to new makers is to learn smithing and metallurgy before going off on alchemist quests.$50 of 1095 and $100 of 5160 is a lifetime supply of steel for some famous makers.I would say when that much metal has been forged,ground,and heat treated,you will have a good grasp of what is going on within the atoms of steel.
 
i thought case hardening is no longer done with chemicals, i thought the steel was baked in an oven with carbon and the steel absorbed some of the carbon. that is why i suggested this method of blademaking. i know chemical hardening would not work very well. i was talking about adding carbon to mild steel, not chemical hardening. steel absorbs carbon in a charcoal forge. and ive heard of a process of adding a high carbon skin by putting the steel in a box of carbon.
 
elven,

I believe a version of your thinking is done industrially. On the other hand I have a small amount of case hardening powder given me that the steel is dipped into or coated with after the steel soaks before hand at a particular temperature. I have not tried using it yet on anything.

RL
 
elvenbladesmith07 said:
i thought case hardening is no longer done with chemicals, i thought the steel was baked in an oven with carbon and the steel absorbed some of the carbon. that is why i suggested this method of blademaking. i know chemical hardening would not work very well. i was talking about adding carbon to mild steel, not chemical hardening. steel absorbs carbon in a charcoal forge. and ive heard of a process of adding a high carbon skin by putting the steel in a box of carbon.
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Just for your information, Carbon and Iron are both chemical elements. Case hardening forms a thin layer of higher FeC content on the surface by a chemical process called solid solution-as the steel is heated with the Carbon, some dissolves into the surface of the steel, hardening it.
 
and that must be what explains why the powder I was given might work. (although I have not tryed it or have felt a wanting to.)

RL
 
I might as well .....case hardening is the addition of carbon ,nitrogen, or boron to a thin layer of the steel . It is done with a solid [ pack carburizing] ,molten salt [CN salts] ,or gas [including patented processes like Tennifer used on guns such as Glock]. Around the shop it's handy to have powder such as Kasenit with which you can apply a thin case with a propane torch.
 
As an individual with no access to a work shop and having only hand tools and a vice, possible access to an angle grinder, and having a hard time finding the right steel for the job, I think mild steel is just the ticket.

I wanted to make some flat stock tomahawk along the line of rmj forges, as well as some of my own desIgns. after finding a big plate of readily available, free mild steel in 1/4 inch, I took it to a metal shop (that did not stock tool steel, and certainly not in the sizes i wanted) and thay cut out three designs for me.

Now I intend to get them pretty colse to filed how I want them, then try a few hardening ideas I have found.

Heat it up yellow hot in a hot charcoal coal bed, let it soak a good couple of hours, get it back up as hot as possible then quench in the brine and soap bath. This is if I can get it up there with a blower and some propane gas.

This I hope will heat enough into the edge and spike that it will be suitable for chopping and defense, but still be soft in the thicker portions to give it plenty of toughness.

I hope to use a similar set up in the future with some leaf springs and a big piece of I beam I saw somewhere that would make a nice anvil. A small out door blacksmith shop. I just have to get some good tips for my first forge.
 
Kevin R. Cashen said:
I think it is because much of the custom blade business has forgotten what knives are for- cutting things! They are not prybars, cold chisels or masonry tool- they are knives. Face it, if we really need to worry about breaking a properly heat treated high carbon blade (that will hold a proper edge), we are doing something wrong and should probably go for another tool for the job.
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Thank You Kevin. I was beginning to think I was the only one in modern times that know what a knife was for. It has gotten totally off track the last few years. A lot of test of the wrong kind. The armchair tactical crowd has fallen off their rocking chairs. Now before every one get a shot off. I SAID ARMCHAIR!
 
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