heat treating metal

[wally b]

I have some old spring harrow teeth that I are pretty worn. I took a new tooth and traced the pattern and ground the old harrow tips as best I could. It is a four ft section I pull with a draft horse.

I was wondering if I could heat treat the metal tips where I have ground it to harden the metal. I have heard that if you heat it up then dip in cold water that this hardens the metal.

Any advice?

Wally

 

[Anonymous-0]

They're already hard if they're spring steel. Oil is often used for heat treating. Another option is to weld hardfacing on them. They'll probably need some preheat before welding unless you use an O/A torch to weld hardfacing on. Check with a welding supply or specialty supplier like Stoody or Eutectic Castolin for the right rods and procedure.

 

[wally b]

How is oil used for heat treating?

Wally

 

[Animal]

quenching

 

[JRSutton]

Oil hardening is very much like water hardening. But the part is less likely to crack in oil than it is in water. Just because the cooling process is a bit slower in oil. (if you use water, be sure to swish it around a lot as it boils and cools to prevent on spot from cooling more than another - increasing the chance of cracking)

heat to I think 1500 degrees (bright red - best way to know you hit the right temperature is that a magnet will no longer be attracted to the metal)

Then dunk it in a pail of oil and swirl it around.

But you also have to work quickly or you'll lose all the carbon to oxygen molecules. heat and dunk immediately - don't mess around, work quickly.

BUT - hardening generally makes the metal very brittle - probably not what you want on a tooth -

You probably want to temper it - right after hardening it, you have to cook it at 350 for an hour, then let it cool on its own.

(how big is this part??)

Going on memory here from a long time ago - but pretty sure I've got it right.

Be prepared for you oil to catch on fire - do it in something where you can smother the flames with a metal cover. have a powder fire extinquisher nearby just in case something goes wrong.

One other thing - where it's the TIP of a part, I'm just not sure about how it'll work out with warping and cracking since you're not doing the whole part. If you can do a test part first, I'd recommend that!

Or perhaps somebody else here has more direct experience than I do.

 

[Ken Macfarlane]

Without knowing what steel they are its tough to give advice. Really high carbon steel with thin sections can be hardened in oil. Thicker sections or lower carbon need water. Mild steel or low carbon steel won't heat treat, all you can do is work harden it by cold rolling, forging, peening, etc that deforms it and it won't get as hard as high carbon steel.

 

[blunosr]

Hi, here is a link to the best video I have ever seen on hardening/heat treating steel. After 2 minutes, he does a very detailed, and easily understood, explanation of hardening, heat treating, and tempering.

http://www.youtube.com/watch?v=RB1qg_OVYmo

Well worth a look.

Bye for now,

Troy

 

[ss55]

You just re-sharpened the worn tips, right?

Unless you went wild with the grinder and got them red hot I doubt that you changed the heat treatment much. They will probably wear about as well as they did originaly without you doing anything more. Worst case you may have to re-sharpen them again after another 200 to 1000 acres.

If it's an old implement the harrow shanks are probably made of a less expensive high carbon spring steel like a 1060 to a 1095 instead of a higher alloy spring steel. The shank tips were probably not heat treated any differently than the rest of the shank.

If you are really concerned you could take one shank to a local black smith or metal shop to identify the metal and see if they need to be re-hardened, drawn and tempered. It wouldn't be worth it unless you see some significant wear happening first.

Good luck.

 

[Fritz Maurer]

Why can't you blow a hole in the tooth near the end and bolt on a small cultivator shovel? I've seen bolt-on tips that look like tiny chisel plow points, and reversible besides.