4140 Heat Treat?

[mmattoon]

Hi folks. Does anyone know where I could find heat treat info for 4140? I aquired a 9"diameter X 6" length of annealled 4140 for 20.00 to use as an anvil.(110lbs.) Not exactly what I was looking for, but the price was right, and I can be sure that it is actually 4140. Any help appreciated. I've searched the web without success. Crucible lists a varient of 4140, but not the base 4140. Thanks, Mark Mattoon

[hammerdownnow]

Sounds like a nice chunk for an anvil. I would be interested in that info also. If you are not going to stick with it for long term, I would not worry about heat treating it. Hitting a soft surface with an errant blow is alot easier on the anvil and the hammer. Dressing out dents is alot easier than dressing chips in the face of either anvil or hammer.

[Quenchcrack]

Austenitize at 1550-1600F, hold for at least 1 hour AT TEMPERATURE. Oil quench. Note: I have water quenched 4145 many times in heavy sections. It either works extremely well or you get your part back in pieces. Temper at 350-400F for an hour AT TEMPERATURE. Allow about 1 hour per inch of thickness just to get the part up to temperature. Now then, assuming you don't have a furnace to do this in, you may want to try flame hardening it. Find a welding shop or heat treat shop that knows how to do this and you can get an Rc50 case on it with fairly tough undercase.

[hammerdownnow]

Quench, how would you go about harding say a 1/4" x 2" by 12" knife blade. I had some throwing knife blanks cut (edm) before I knew much and can't figure the best way to treat them, thanks.

[mmattoon]

Originally Posted by Quenchcrack

Austenitize at 1550-1600F, hold for at least 1 hour AT TEMPERATURE. Oil quench. Temper at 350-400F for an hour AT TEMPERATURE. Allow about 1 hour per inch of thickness just to get the part up to temperature. Now then, assuming you don't have a furnace to do this in, you may want to try flame hardening it.

Quenchcrack, let me see if I've got this straight. Assuming my 6"x9" chunk, I would want to get it to 1550-1600F for at least an hour at temperature, oil quench, then temper right away at 350-400F for about 6 hours. I've got some ideas for a temporary heat treat set up, but it may be easier to set up for case hardening using a forge burner and tempil (sp?) sticks. Thanks for the info. It is much appreciated. Mark Mattoon

[Quenchcrack]

To heat treat a 4140 blade use the same temperatures but scale back the time. Normal hold times are designed to allow the heat to penetrate thick sections so if you have only a 1/4" section, reduce the hold time to 15-20 minutes. If the 4140 has been annealed, you may want to increase the hold to 45-60 minutes to dissolve the carbides. Oil quenching of blades is highly recommended. I have done it in water but it is very risky and distortion is almost always a problem. I have actually used compressed air to quench 4140 but I do not think this will achieve the best hardness.

[Quenchcrack]

I have never done an anvil with a rosebud but I am told that it is important to tilt the face to be hardened at about 45 degrees and start at the bottom and work up. It would be best if the torch could heat the entire width of the face as you water quench it. Go to anvilfire and do a search for this technique or ask the Guru for more details. If you are going to try to heat and quench the entire end before quenching, make sure your bottles are full. Wouldn't hurt to put a nice radius on the corners first, either and grind the face nice and smooth. Good luck. Oh, one more detail: it is probably as hard as one of those Russian Anvils if it has been normalized. For a starter anvil, that might be hard enough.

[Mark Williams]

Build a big fire in a wheel barrow and dump it in a lake when you get it up to critical.

[mmattoon]

I was thinking of drilling and tapping a 1/2 hole in the side for an eye bolt to move it with when hot, with the assisstance of an engine hoist. Still trying to figure out what I have lying around that would be big enough/heat resistant enough to line with ceramic wool for a temporary oven. I've got a 35 gallon iron pot I can fill with used motor oil, even heat it a bit for quench. The wheel barrow idea isn't bad if there wasn't the risk of fracture. I do have a small coal forge that would probably get 1/2 of the piece close to 1550F. Thanks again quenchcrack. Mark

[Mike Sader]

Mark, have you used a hammer to check for rebound?I have access to some 4140 in 3" square stock and used it last nite for an anvil. It worked great, but I needed to secure it a little better. This piece is about 2' long but still moved around too much. Anyway good luck, Mike

[mmattoon]

Mike, if I remember correctly, a 1lb. engineer's hammer rebounded about 4"-5" when dropped from about 8". I will probably skip trying to harden this for a while. I got a good deal on a new old stock Austrian style anvil from Euroanvils. 175lb. for 275.00. Should be delivered tomorrow. I'm thinking I will probably grind the face flat on the chunk of 4140, use it as a bench anvil for a while. Thanks again to all for the suggestions. Mark Mattoon