Another fire steel question

[rustyh]

I've got a couple of steels that I think need to be hardened/rehardened. I can get a few sparks but not alot. What is the best way to harden the steel. I have access to a oxy/actl torch at work to do the heating.

 

[Flint311]

I've got one that won't spark real well, but makes a huge difference with the stone I use and how sharp it is. This may make a difference (?). Just for an idea....

 

[skunkskinner]

It's simple, heat it till it's bright red maybe orange then drop it in a can of water.

 

[buffcreekforge]

I build a bunch of them every year and I find that they spark hotter when I heat cycle them (a tip from the late Mike Ameling). Heat the steel to low orange, lay it on the ground and let it cool to room temperature 2X. Then heat it to orange and quench in water. I usually try to move the steel around in the water as I quench it - seems work best. My steels throw a shower of sparks on good, sharp flint sherds. Good luck!

Just Dave

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[Jim Blair]

Black Dave gives good advice.When rehardening,it always works best to anneal it so it is back to it's original soft state then re-harden.If your restricted to an oxy-acet. torch for better heating results you might build a box open on one end out of firebrick loosely laid upon each other with one closing one open end.

 

[LRB]

Annealing is not the same as heat cycling, and really would not be necessary in a re-hardening process. Mike heat cycled to try and prevent cracking and breaking in the quench. Heat cycling is best done in three steps. Step 1 is to take the steel to or above quench temp, then let air cool. Step 2 is to take the heat a little past non-magnetic then air cool. Step 3 take the heat up to a low red below non-magnetic and let cool. Then heat and quench. Step 1 makes the grain more even in size. Step 2 refines the grain and makes it smaller. Step 3 further refines the grain and relaxes any stresses caused by 1 and 2. Finer grain = stronger structure.

 

[buffcreekforge]

As always, Wick's advice is solid. Heat cycling has pretty much eliminated steels shattering when you quench them. I can't claim to understand all the science behind the methods Wick suggests, but they work. I read all Wick's posts because it helps me out with making a better product. He knows what he is talking about when it comes to heat treating steel. Thanks!

Just Dave

 

[Jim Blair]

Interesting,I've never heard that term before.That's the method I used to re-point jackhammer bits years ago before they just threw them away and bought a new one.Or pretty much any tool like that such as cold chisels.Just tempered them out to different colors depending on what they were used for.For the initial step I stuck them in a 5 gallon bucket of cat litter,it seemed to allow the longest cooling off time.

 

[rustyh]

Thanks guys I'll give it a try and see what happens.

 

[LRB]

Depends on the steel. With steels of more than .8% carbon, slow cooling is not desired when heat cycling. If the steel cools too slowly from the initial high heat, the carbon will reform as unevenly dispersed layers and carbides can collect in the grain boundaries making a weaker structure. Air cooling does not allow time for this to happen to any great degree. At the second heat cycle, just above non-magnetic, some recommend quenching to lock the solution in place. I have not yet tried this. Then a few cycles at low red, below non-magnetic will further refine the size of the grains and the size and number of the carbon spheres which carbon forms to at this heat range, making a fine structure ready for the final heat and quench, at about 40° to 50° over non magnetic. With simple steels of this carbon range, higher heats can be detrimental to the structure you have prepared.

 

[Jim Blair]

Thanks for the explanation. :hatsoff:

 

[rustyh]

Well I heat cycled both steels one still doesn't work very good but the other one throws alot more sparks now, not what I would call a shower but it is better. I made some some new char cloth today and got fire on the second strike.

 

[skunkskinner]

:thumbsup:

 

[fatboy]

Sounds like you have had some good luck the other one maybe made of lower carbon steel or maybe you just need to retry the process. Good char is a must and a good edge on your flint is also IMHO

 

[caintuck rifle]

Be careful quenching it cools the steel very quickly and i have had items crack on me