case hardening with ashes from fire

[BrokenBiker]

is it feasible to case harden steel using the ashes from a wood and coal fire?

the thought was put into my head watching a blacksmith while waiting for some steel earlier.

he mentioned using his own blend of substances to case harden stuff but didn't mention what it was

 

[ford34/2]

I have used crushed barbecue charcoal, heat the metal to red, and then cover the item in the crushed charcoal, leave for an hour then cool in water about 20C.Idealy a container bigger than your item so it is placed in and covered.

Stan

 

[BrokenBiker]

i thought it would need un burnt carbon as opposed to the remains of the fire.

i had never thought to use charcoal or coal though even though i have an abundant supply for my nans fire

 

[ronan]

The people in the firearms industry used to use (and some still do) horse bone charcoal, leather , urine i am told etc, though this can be done to get nice colours on the parts as well as hardening the metals surface. Search "colour case hardening" on youtube.

 

[BrokenBiker]

id heard about urine, think it may have been the gun smith i use that told me about it actually when i took my sabel sxs for a service. That had loads of colour in it

 

[Wendelspanswick]

You can still buy Kasenite for case hardening.

 

[ronan]

You can still buy Kasenite for case hardening.

Yes but its not nearly as good as it used to be, the 'elf and safety brigade got the cyanide removed from it, even though i never heard of anyone getting poisoned with the old stuff.

 

[MattF]

is it feasible to case harden steel using the ashes from a wood and coal fire?

Any powder which is carbon rich will work. Doesn't matter what it is. Bone meal or aquatic carbon are probably the simplest and most readily available options, if you don't want to sort your own.

 

[BrokenBiker]

i have kasenit but as mentioned its not as good anymore. Will try the crushed up coal and see how i get on. Will try ashes too and see if that works

 

[ronan]

There is another hardening compound, cherry red or something its called, anyone tried it ?

 

[BrokenBiker]

seen it on ebay, haven't tried it but cant see it being much different to kasenit without being able to put cyanide in it

 

[julianthegypsy]

Best if you can keep it at heat for an extended period of time.

 

[ronan]

Best if you can keep it at heat for an extended period of time.

Yes i believe the pores in the metal surface open and the carbon is absorbed into it.

 

[MattF]

It's a depth thing. Time relates to depth of penetration.

 

[ronan]

Nitriding and tufftriding is another case hardening process that we used to get done in my old job, cannot be done at home of course, but the surface gets extremely hard, and it wasn't too expensive to get done.

 

[Wendelspanswick]

I have had good success with the modern Kasenite, I machined up a bush for a Stuart Turner P66 engine and used Kasenite to harden it.
I made a metal box slightly bigger than the bush, put the bush in and then packed the Kasenite round it and put it in the forge with the coals just glowing for an hour. I set up a decent air grinder on the lathe to grind it down to finish size.
I was really impressed with the depth and hardness developed by the Kasenite.

 

[Sid]

Yes i believe the pores in the metal surface open and the carbon is absorbed into it.

The pores?

Case hardening is a diffusion process of carbon into the crystalline structure of the metal. As you can imagine this can only happen at high temperatures, and is extremely slow. You'll also get a tailing away of the concentration of the carbon with depth.

 

[BrokenBiker]

I have had good success with the modern Kasenite, I machined up a bush for a Stuart Turner P66 engine and used Kasenite to harden it.
I made a metal box slightly bigger than the bush, put the bush in and then packed the Kasenite round it and put it in the forge with the coals just glowing for an hour. I set up a decent air grinder on the lathe to grind it down to finish size.
I was really impressed with the depth and hardness developed by the Kasenite.

ive only ever heated the metal up to cherry, stuck it in as deep as i can then let it cool. Clean up and repeat if needed

 

[ronan]

The pores?

A simplification , not everyone here is a metallurgist.

 

[ronan]

A member on a model engineering forum was recommending aquarium charcoal as a hardening compound, i suppose if its carbon rich it will work to some extent.