4140 heat treat?

Will52100

Will52100

Joined
Dec 4, 2001
Messages
3,824
Got a 4"x4''x12" piece of 4140 coming and will be making a post anvil out of it. What's the best way to heat treat? I've had good luck with spring fullers and such simply heating to critical and quenching in water. I'm thinking heat the end in the gas forge, say about 4-6 inches to critical and dunk in a bucket of water.

Any idea of the hardness I can get? With the size of the 4x4, would it be a good idea to make a brine, or would regular well water work just fine? Not going to be a heavy forging anvil, just for finish and for bevels. Planning on welding angle iron and plate to the lower half, turning upside down and filling with concrete and and then burying the the thing about a foot in the ground.

Thanks
 
Bucket of water ? That doesn't sound like enough ! And I'd like to see oil . such as canola, safer than water.
 
I was thinking I'd need a bit bigger than a 5 gallon bucket. Will most likely be a tub, about 15 gallons, also have a water hose running into it.

No way is oil going to be fast enough for that thick a cross section. Oil isn't really fast enough even for smaller sections of 4140, like 3/4" thick flat bar.
 
Brine would work better. You should also try austenitizing at higher range, something like 1600f.
 
Thanks, that's what I was thinking, but wasn't sure. I take it no temper is necessary?
 
Waterfall.
Literally- that's how they did it back in the day. Most mills and workshops were powered by streams.
That gives you an idea of how much cooling power you need.
 
Thanks, since it's going to be heavy, I'll probably rig up a jin pole and chain, it'll be pretty easy to have a 55 gallon drum ready to dunk it as well.
 
You will want something that you can swirl it around with as well to introduce some agitation. Just a piece of pipe attached to the side so you can push/pull circle the steel in the quench should do dandy.
 
Was thinking of adding about 4' pipe to the water hose and stick that in the bottom of the drum, use it to circulate the water.

Thanks
 
That should work magnanimously if just using water for the quenchant. Most water hoses have little trouble exceeding 6gpm which is a good rule of thumb for agitation via circulation. Of course in the case of such a large piece I doubt more flow would hurt if you have it.
 
Got it heat treated, first attempt in plain water was a failure, barley any noticeable increase in hardness. So I figured I'd try a batch of super quench. Mixed up 20 gallons worth, probably should have gone with 35-30, but cost adds up quick. Any way came out nice and hard. Figure the hardness at maybe 51-52 from file test and whacking it with the peen end of a ball peen. Nowhere near as hard as my Refflinghaus anvil, but nowhere near as soft as the old harbor freight Russian steel anvil I'd been using for years. I did do a few experiments with 1018 and it made it a hair harder, might be useful when I make tongs.

Now just got to dress the face as it sunk in about 1/8" in the center. And of course get it mounted.
 
Keep an eye on that center spot you may develop a crack around that area. That's what happened to min from the video here.

[video=youtube_share;9rA5rqf8nM4]http://youtu.be/9rA5rqf8nM4?list=UU35XkHHFe1TwOSL_91osYrA[/video]

About a week after heat treat and temper it started developing a fine circular crack in the center. and that was before doing any major banging on it. We'll see what happens on the next on, gonna do a 1045 stump anvil in a super quench and see what happens.
 
Good to know. I thought it had cracked, there was a surface crack about half way around the center about a 1/2" into it. After a little light grinding to clean up and level it up it disappeared. Hopefully it didn't go deeper.

I can't see the video, on limited bandwidth rite now. I'll check it out when I get back stateside. Looks like you did one out of square stock like mine?
 
What temp did you temper at? I don't know a lot about 4140 heat treat, but while looking for info on 1045 I found some info that suggested lower tempering temps could cause brittleness? I don't plan on tempering, I heated pretty much the whole thing to critical and quenched, but the center about an inch from the surface glowed red a bit longer than the rest and heated the water to nearly boiling. Figure that was a stress relief. If I could get my hands on a 1045 chunk I'd probably used it. Of course before I go buying more steel I'll probably be cheaper to cut down a halfway decent smaller anvil like I did for my harbor freight cast steel one. That one I cut the horn off and it worked well for blades, but was still pretty soft.
 
How did you judge critical temperature? Definitely temper if possible, but stay below 415 F or above 650 F. With a piece that big, it's likely it didn't harden all the way to the center, but that may not matter for your uses.
 
From color and a rare earth magnet on a wire. I check with a smaller piece in my oven with a magnet and lights out to get a feel for the color before trying the larger piece in the gas forge.
 
You must log in or register to reply here.
Back
Top