Heat treating A36 (not a knife)

N

navasky

Joined
Dec 7, 2009
Messages
74
I just made a couple of sheet metal stakes out of huge bolts. They don't harden in water, but harden up a little in superquench. I'm pretty sure they're just A36. I'd like to get them harder, is it permissible to heat them up to orange or yellow before quenching or is it likely to cause grain growth. I vaguely remember hearing something about quenching low carbon steels extra hot but I could be wrong.
 
You can't make steel harder by heating to a higher temp.

You have to go to a different material, try a higher grade of bolt, or use W1 drill rod.
 
You can pack it in bone meal and try a case hardening.
Weld up a simple steel box from 1/4" plate, fill it with charred bone meal with the pieces of A36 in the middle, put a layer of refractory clay on the bone meal, then a piece of 1/4" steel as a top plate. When done, wrap the assembly tightly with iron wire. Place in the forge or oven and heat for 2-3 hours at a red color ( around 1300F). When done, open the box and dump the pieces out into a large bucket of ice water.

This will get you a pretty darn hard shell over a soft core.
 
Someone correct me if I'm wrong, but my understanding is that all Superquench will get you is some surface hardening, especially on a thick section like what you describe, so you're not that likely to get cracking on something that's just used as a forming stake.
I can't see that some grain growth would be an issue, if it happened at all. I'd run it up to critical and SQ it and go to town...the people (Rob Gunther?) who publicized the recipe for SQ used A36 for hammer dies and top tools and got decent life out of them, so.....
 
The bone meal is a way to do case hardening. Carbon from the bone meal migrates into the surface of the tool placed in the box.
I've heard of wrapping the tool in leather for case hardening too.
Cherry red or casenite is a horribly noxious chemical. It works, but it smells like it'll probably kill you, plus its expensive.
 
Last edited:
Cyanide works well for case hardening, too.....but it probably isn't a good choice for home projects :)
 
If it is only about carbon availability, couldn't you just heat it in charcoal?

-Sandow
 
The charcoal will work to some degree, but will burn up unless well sealed from oxygen. You can't just stick the steel in a charcoal grill.
Bone meal is the norm from what I remember.
 
Thanks for the suggestions everyone. I'll probably pick up some of the cherry red since keeping things red hot for hours in my charcoal forge sounds expensive over the long term.
 
You must log in or register to reply here.
Back
Top