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heat treating my homemade anvil


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Hey all, i am attempting to harden my homemade anvil right now. I work in steel mill so i put it in the furnace about 30 minutes ago. I'm guessing it weighs about 100 lbs. and I think it's what we in the rebar buisiness call #60 grade steel. Once the temp is right I'll pull it out and throw it in the flume full of running water. My question is what is the right temp?

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Hey y'all back Downfish, glad to have ya.

I have no idea what #60 grade steel is so can't give specifics for heat treatment. As a general rule of thumb you'd brind it to critical temp, a couple hundred degrees above non-magnetic so for general use non-magnetic is good enough. A piece that size will need considerable soak time at temp to heat through.

Tempering is usually the critical part of heat treating and without knowing the characteristics of #60 grade steel it's pretty useless to suggest a tempering temperature / color.

It would've been better to do some research before you started heating your anvil. Heck, there's probably someone in the mill who could've told you exactly what you need to know.

To be conservative (with the caveat I don't know what the steel is) I'd probably draw it to purple. It's much better to have an anvil that's softer than optimum than have one that's prone to chipping.

The snapping/cracking sound you hear when a piece of steel chips is the chip breaking the sound barrier. You'll be standing close enough to the anvil the chip can hit you at bullet speed just about femoral artery level. This is . . . BAD.

Frosty

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frosty' i just had a piece tested and have the results, what specifics do you need to know? The sheet just gives me 2 letter abrevs., i'll guess some carbon is .391, manganese is 1.135, cromium .025, nickel .185, vanadium .028 that's about a third of the values. The billets are coming out of the furnace 1970 deg after soaking for about 90 min.

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Aw, chuck it in the water! 1820 is pretty hot, but what the heck. Purple is the draw after quenching. Try to grind and polish the face a little and then set it on a hot billet till you see purple on the face and chuck it in the water again or it'll keep going and get too soft.

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I tried again today and it worked great, I think, I mean it's a lot harder than it was. Our ping tester is broke so I came down really hard on a corner trying to chip it without success, so that seems good. I didn't have much time to work on it, just barely hit it with a grinder and wow did it scale up bad, but it'll clean up. So what do you think?

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17414.attach

17415.attach

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frosty' i just had a piece tested and have the results, what specifics do you need to know? The sheet just gives me 2 letter abrevs., i'll guess some carbon is .391, manganese is 1.135, cromium .025, nickel .185, vanadium .028 that's about a third of the values. The billets are coming out of the furnace 1970 deg after soaking for about 90 min.


DF, I think you did some bit of harm with this first heating, way too hot for way too long! You grew the grains of the steel, as well as created a skin of decarb that is probably .125" thick! Decarb means that whatever little bit of carbon was in the steel has probably been burned right out of it. If it is hard, and survived the heat treatment that you did then awesome, but if you are going to make another go of it, I would suggest bringing it up to about 1600F and letting it soak there for about 30 minutes, then quench in the water. That or try and find the spec sheets, should have been with the same paper that said what alloys were in it. It will give you your Austeneitizing temperature (the temp you heat it up before quenching) and Rockwell C or B hardnesses at specific tempering temperatures.
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I like it! Well designed and executed is exactly right.

I think you did well, very well.

Sorry about tossing in a quick two bits and not checking back yesterday, I had a birthday to go to. However seeing as your iron was in the fire I thought I should toss out something basic quick and expect the guys who really know their heat treat would correct any mistakes I made.

Frosty

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What a great looking anvil!!

Has all the goodies and looks compact for a smaller place, but sturdy enough to handle almost anything. Is it your design / home made? if so, make more and sell them, lol. what are the dimensions?

Edited by mod07
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Thanks for the kind words, I tested the hardness today and in 8 spots it averaged 54 on the rockwell C scale, low of 46 and high of 60.

What causes the decarb? was it the high heat, length of soak time or do you think it might be how they were fireing the furnace (rich or lean)? It must not be a loose layer cause we pinged it right on some of the spots and they were as good as the rest.

DennisG it started as a 5 1/2" billet which is what we run. I made a 30 deg cut for the heel, then I used that drop for the horn. I beveled the base of the horn back about 1" back and 2" into the root and welded it on. Then I milled the 1" hardie hole in the side and drilled the 5/8" pritchel hole. I full pen welded a 1/2" piece of key stock in to close up the hardie then welded a 1" plate onto that side with a 45 deg bevel all around and a 2" rectangle in the center. that left about 2" not welded on that side plate and that was the soft spot when I tested the hardness. Then I welded it to a 2" plate with some holes to mount it.

The anvil itself is 5 1/2" tall, 6 1/2" wide, 14" long, with a 6" horn set 1/2" down from the face, setting on a 2" thick base 10 1/2" wide, 16" long with the back side radiused. I was just trying to make it look like an anvil :D

Thanks again for all the help.

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De-carb is caused by a lean fuel/air rich fire. It is the removal of carbon from the part through diffusion. If the furnace is rich fuel/lean air then it is possible to ADD carbon, but this is typically slower due to concentrations of elements. Electric furnaces without a blanket gas are lean fuel. A blanket gas can be as simple as added carbon to "absorb" O2.

Phil

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Nice job! That's easily one of the nicer homemade anvils I've seen -- horn, hardy hole, the whole bit! And heat treated, too! Awesome!

Sam is almost certainly right that you caused the grain to grow by soaking so hot for so long. However, there is a plus side to larger grain size: it increases hardenability (i.e., makes the steel deeper-hardening). With 0.4% carbon and a mass that large, increased hardenability may not have been a bad thing. The downside to large grain is brittleness. But if you deliberately tried chipping the edges and weren't able to do so, I'm guessing it probably isn't too brittle.

Update: I just saw the results of your Rockwell test. That's pretty impressive! I would worry that the RC60 spots might be a bit brittle. I've read that some good quality old anvils were that hard, but I'm guessing the heat treat on those was pretty carefully controlled to keep brittleness to a minimum. You might want to be a little careful about those hard spots. Maybe think about tempering them back to mid-50s, unless you're really sure they're OK.

Edited by MattBower
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Pkrankow: I'm really not trying to beat up on you, actually I think your posts are well thought out and generally pretty accurate. I used to believe that a lean mixture was the worst for decarburization too, but according to Carpenter Tool Steel, the worst is a neutral fire and they recommend a slightly oxidizing fire. According to their research, a layer of scale actually hinders decarburization.

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Grant, I honestly didn't set out to try and contradict you on this. I started Googling around because I believed you, and this was so contrary to all I've ever read/heard that I wanted to read the details straight from Carpenter, so I could have my ducks in a row when I started telling folks that oxidizing atmospheres actually help prevent decarb. But here's what I found in Carpenter's own online glossary:

Decarburization - Removal of carbon from the outer surface of iron or steel, usually by heating in an oxidizing or reducing atmosphere. Water vapor, oxygen and carbon dioxide are strong decarburizers. Reheating with adhering scale is also strongly decarburizing in action.


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Interesting indeed. I have my Carpenter book in my hand. Under decarburization: ""when controlled-atmosphere furnaces or neutral salt bath is not available, the use of an oxidizing atmosphere would positively prevent a soft skin". MattBower's second reference seems to confirm this to some degree.

"by heating in an oxidizing or reducing atmosphere". Wow. Either one according to that. So, now what? Guess we can all just do it how we like.

Edited by nakedanvil
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I asked a metallurgist with lots of heat treating experience to pop over here and see if he can help us sort this out. I don't know if he'll find the time or not. Quenchcrack might be able to help, but he hasn't been around these parts for quite a while. (Bob, you out there? Everything OK?)

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Sooo when i make the next one the process should be?...

-since i don't have control over whether the furnace is running rich or lean to avoid the decarb, which is a drag to remove.
-bring it up to temp, non magnetic or 1500 ish.
-don't let it soak.
-take it out and quench or should i normalize once then quench?

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