heat treating larger 4140

[Metalhead0483]

Hey all, I'm finally getting a post anvil set up in my garage. I ordered a 4" wide piece of 4140 round bar from our local steel supply yesterday (only suitable material they had) which should show up here in about a week, depending on which truck they can get it on from Anchorage. My question is in heat treat, and specifically the quench, as heating it up is no problem.

My understanding is you need lots of coolant and agitation when quenching stock that size, but I don't really have a concept of what that means. Are we talking 55 gallon drum full of water here? Or like a fire hose? Anyone have any experience they'd care to share?

 

[JTknives]

how long is it, that will make a big difference.

 

[kuraki]

Also, most of the talk about the extra steps to take on large cross sections are what you need to do to achieve the best case of hardening all the way through. Where, for a post anvil if it hardens a 1/2" deep or so on your face, who cares if it hardens past that.

 

[Geoff Flato]

5 gallons would probably be sufficient, a garbage can full would be ideal. 4140 anvils are surprisingly forgiving for HT. I wrapped in HT foil, and soaked for about an hour or two insuring it's heated through. Pull it out, quickly cut the foil off, and quench it in water. It's worked great for the few I've done

 

[Metalhead0483]

It's 12" long JT. 4" diameter by a foot long. I'm planning on welding up a wider piece of pipe (probably 5"i.d.) on a base, filling the pipe about 3/4 full with gravel to set the 4140 on and drive semi-permanent wedges in around it to maintain stability. I'm hoping that will give the whole thing plenty of mass without me having to fork out the ridiculous money for a longer piece of chromoly.

Huh. So really a good agitated quench in a good size container of water would work well enough for what needs doing? Interesting...

 

[kuraki]

Just to be sure, you're saying you want to put your quench oil container into another water filled container, or you intend to water quench this 4140?

Also, you may want to see how hard it is as it arrives, unless the place you bought it from told you. The hot rolled plate I have is about 45-50 RC as it comes, at least the skin of it is.

 

[Nathan the Machinist]

Most 4140 I've bought was annealed. Even the "pre hard" stuff I've bought wasn't 45 and isn't hard enough to be an anvil. I think the face might ought to be around 55 huh? I'd plan on it needing a HT.

If it were me and I was doing it here, I'd set up near the kiddy pool (it's a salt water pool!) and dip it underwater with the face in front of the output of the filter pump...

If it's 4X4X12 it's going to weigh 54 lbs. 4" round 42 1/2. That's heavy but manageable.

4140 can be quenched in oil or water. Such a big pieces is going to have trouble in a normal knife maker's quench setup and will need quite a bit of fluid and won't quench well in 5 gallons of oil. That will catch on fire and be under quenched. I think you'd need more than 20 gallons of oil for 54 pounds.

It's gonna need a long soak so you're going to have some decarb. If it were me I'd grind it off.

 

[Darrin Sanders]

Here is an excellent video my buddy Charlie Lewis made on making a post anvil out of 4140. Be sure to check out the rebound he gets after it was finished.

 

[coldsteelburns]

Just a little off topic, but you say you are going to fill the anvil pipe stand up with gravel (pea gravel I'm assuming), and I have been wondering for a while now (as I still don't have my hardened and tempered 4x4x11" post anvil from OWA mounted) if sand would be better. I know Charlie used pea gravel for his, but I'm still curious if the denseness of sand wouldn't be better?

I am also wondering if putting a piece of thick rebar (or the like) underneath the anvil through the length of the pipe so it contacts the ground. I believe I read about this a few years ago ad how it may help with extra rebound loss.

Hope you don't mind me asking these questions here. I'll edit them out if not.

~Paul
My YT Channel
Lsubslimed
... (It's been a few years since my last upload)

 

[Metalhead0483]

Yeah I follow Charlie on youtube, and have seen his quench video. Actually it was his videos that first sold me on this sort of setup, and I'm basing the overall project on his design (although I went for a slightly thicker piece of steel). It looked like he used a pretty big container of water for his quench. I did find it interesting that he didn't temper afterwards.

To answer some of the other questions and comments. The 4140 I have available here is hot rolled, TG&P. It will be about 23hrc as it comes from the supplier, so not good enough for what we're talking about. I do plan on doing a water quench Nathan. That much oil would make me very nervous (not to mention being REALLY expensive) Upon consideration I think I'll use a 55 gallon drum (which I can pick up for nothing) and agitate the steel vigorously during the quench.

 

[Metalhead0483]

Coldsteel, I sure don't mind you asking questions. That's what the forum is all about. I'm not sure what difference sand vs gravel would make. Honestly though, I was impressed enough with Charlie's build that I think I'll stick with his way. Also, gravel is cheaper

The rebar idea is an interesting one, and might be something I'd pursue. I'm planning on drilling and tapping the bottom of the 4140 anyway to aid in control during the quench. Wouldn't be any big thing to tap some material of the correct length and see how much of a difference it makes...

 

[Geoff Flato]

A length of pipe with a bunch of small holes drilled in it, hooked up to an air compressor and tossed in the bottom of the quench tank will keep the water plenty agitated

 

[Nathan the Machinist]

I do plan on doing a water quench Nathan. That much oil would make me very nervous (not to mention being REALLY expensive) Upon consideration I think I'll use a 55 gallon drum (which I can pick up for nothing) and agitate the steel vigorously during the quench.

Having oil quenched a bunch of 4 pound hammer heads in 5 gallons of oil I can tell you from first hand experience your nervousness is well justified. My hairline was receding just fine by itself.

 

[Metalhead0483]

Hah! I feel your pain Nathan

 

[Atlas Knife Company]

I recall watching a youtube vid where the anvil was fastened to the trailer hitch of a truck and backed into a swift moving river. It was quite a bit more than 54 lbs. . .

 

[Willie71]

I've got 20 gallons of medium speed oil for hammer heads and axe heads and such. I wouldn't try to pull an anvil off in 5 gallons. For an anvil I'd do it in a 55gallon drum of water. Weld a thick hook or eye on the end to make it easier to lift with a 1" steel bar with 2 people.

Look up the issue the DesRosiers (sp?) had when quenching an oversize piece in their shop. They lost everything, including pets. Do this outside and have fire extinguishers ready.

 

[Metalhead0483]

I recall watching a youtube vid where the anvil was fastened to the trailer hitch of a truck and backed into a swift moving river. It was quite a bit more than 54 lbs. . .

Don't laugh, I seriously considered doing that in the Chena river. I think it's probably a bit overkill though.

Look up the issue the DesRosiers (sp?) had when quenching an oversize piece in their shop. They lost everything, including pets. Do this outside and have fire extinguishers ready.

Very much going to be a water quench, for that very reason.

 

[Stacy E. Apelt - Bladesmith]

One option many don't consider is sending bit to a HT company. Peter's will do it for something like $50. Many industrial and machine shop HT providers can do a very large piece. Considering the amount of fuel, risk, and varied results from DIY HT on an anvil, this is a pretty good option.