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Couple of dumb questions about crucibles ect.


Kreg Whitehead
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To prelude this PLEASE correct and wrong terminology I am probably about to use here.

This spring I want to try my hand and making some iron bloomery......the add in of non carbon steel to make it high carbon.

I do not have a press,power hammer,or even a legit anvil so I dont think I want to attempt to consolidate it by hand.

I have been wanting to get a crucible set up to melt it into one piece.

 1st dumb question;Would that be considered crucible steel? wootz??

2nd dumb question......is there a reason that guys leave in in a puck rather than trying to pour it into a bar in some casting sand....say 3/8 to 1/2 " thick.

I think with the equipment I am working with that would be a real time saver.

3rd  dumb question. Is there a reason I couldnt melt down a bunch of high carbon scrapes 5160, w2 15n20, ect and pour it into a bar.

I have been wanting to try my hand at casting some guards also.

Any recommendations on a good value in a crucible set up(propane) would be appreciated.

3rd dumb question....I cant remember the term for the little 7 brick and blower deal...think it starts with a T.

4th dumb question;Would that work for the crucible melt part also instead of a propane set up??

I am not afraid to save some money =)

 

 

Edited by Kreg Whitehead
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Dumb answers coming! ;)

 

You're describing at least four different ways to make steel, and yeah, it's confusing, so let's start with what you want to do most, which is to take scraps and make a bar.  The easiest way to do that is the second dumb question #3, the hearth melt.  With that you're replacing a crucible with a tower of charcoal, and melting the scraps through said charcoal so they form a more or less homogenous puck at the bottom.  This can then be hammered out into a bar.  It's not gonna be clean, it's gonna have slag inclusions, but it'll have a funky pattern.  Read Aiden, Daniel, and Emiliano's stuff about hearth steel here in this subforum to get a better handle on that.  It's a little risky using high carbon as your feedstock, since it tends to carburize on the way down anyway, so you might end up with cast iron.  To fix that, use a stronger air blast during the melt to deliberately decarb the charge.  Emiliano did that with a leaf spring at Ashokan a few years back with good results.  Lots of sparks, too!

 

1st dumb answer: Wootz is just one kind of crucible steel.  It's very high carbon, like 1.5 - 1.75% C.  You can also make lower carbon crucible steel, but it's not going to be wootz for technical reasons.  Lots of info about that around here, if you really want to break your brain. I don't know enough to tell you how to do it. :unsure:

 

2nd dumb answer: you leave it in a puck so it doesn't get oxidized and porous.  Steel really hates being cast in small bars with low tech equipment.  Back when they were making crucible/cast steel tool steels, they'd melt a big pot of from 40 to 60 pounds of high carbon shear steel (another process made by carburizing wrought iron), skim off the slag, and pour that into a preheated fireclay ingot mold at white heat, often with an extra top section of fireclay, then let that cool slowly for a few days.  The extra top was to handle shrinking, which is a big thing with steel.  If you don't use a false top and it cools too fast, you'll get a hole down into the ingot that can go a long way down, or even all the way through.  This is called piping, and is a Bad Thing.  Reason #2 for leaving it in larger ingots is grain size.  Cast steel grain is huge, and forging down the pucks or big billets refines the grain enough to be usable. If you look at modern steelmaking you'll see them pour a big rectangular billet which then gets hot-rolled down to size.  You have to reduce it quite a bit to get good steel that way.  

 

First third dumb answer: See answer to previous question.  Unless you've got all sorts of kilns and molds and such, you're not gonna be casting usable high carbon steel small parts.  For that you need vacuum investment casting, and that ain't cheap or easy with steel.  A lot of modern gun parts are made that way, though.

 

4th dumb answer:  Yep, you can use charcoal as fuel for a crucible furnace.  That's what they used to make wootz in central Asia back in the day, and when Huntsman discovered the crucible process in the 1760s he used coal.  The setup will be slightly different than the standard hearth.  This:  https://gingerybookstore.com/charcoalfoundry.html is probably the simplest way to do it.  There's a lot of home foundry stuff out there, but keep in mind they're usually pouring cast iron or brass, not steel.  Iron's a weird thing.  When you start adding carbon the properties change fast. Under around 0.08% carbon, it casts okay, but is a little gummy. Over about 3.5% carbon, it casts beautifully, and runs like water.  In between the two it will fight you.  Alloying elements will segregate, it'll get all foamy, it'll suck up oxygen from the air, and generally misbehave.  

 

Hopefully Jerrod will chime in on why steel is hard to cast, since he works in a steel foundry.   

 

As for crucible types and so on, fireclay's cheapest and most fragile, clay graphite is a bit better, pure graphite and silicon carbide are better still (and much more expensive!)  If you go this way, remember you'll be picking up a pot of liquid steel and pouring it somewhere (unless you leave it for a puck), so strong is good.  The last thing you want is for a full crucible to split open on your shoes.  :ph34r:

 

Be careful listening to me about this, though.  I've participated in a few wootz runs (i.e. stood there watching while someone else did it), failed spectacularly in the two I tried myself using direct reduction of ore, done three or four successful short-stack bloomery furnace runs of wrought iron, and two decent runs of hearth steel.  I know the theory of much of it, but theory isn't the equal of experience.  

 

 

Edit: It just occurred to me, you got hold of a mild steel wagon tire last year, didn't you?  That's perfect feedstock for a hearth melt.  

Edited by Alan Longmire
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Thanks Alan. I was hoping to not have to go to pound town on a puck with my hammer and piece of r r track.

I kind of assumed there was a reason I never see or hear about guys casting into bars/billets,I figured there would be no better place to ask than here.

Guess its time to check out some of the press builds on here. 

And yes on the wagon tire.

Edited by Kreg Whitehead
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Discussing casting of steel is a tough one.  On the one hand, I want everyone to be able to experience it, because it is an awesome thing.  On the other hand, it sure isn't easy and not something to approach lightly.  

 

Casting in general has a lot of intricacies to it, many of which have been discussed on the forum already.  One thing that isn't talked about as much as it should be is pouring temperature and superheat.  When we melt steel we pretty much always get it to at least 3000F.  It doesn't always need to get that hot, but it helps as we process it a lot.  Sometimes it does need to get that hot though.  It is not uncommon for us to tap (pour from the furnace to the ladle) at 3000 F.  We lose about 75-150F when tapping.  Every pour, we need to consider the alloy's solidus temp (fun fact, that is not the same temperature as its liquidus) as well as the geometry.  The mold is going to start cooling the metal as soon as they come in contact with each other, so a thin rangy part will need to start off quite a bit hotter than a solid lump due to all the surface area per volume.  

 

When making a pattern for your part, you need to think of pattern shrink, rigging, and detail/geometry.  

Pattern shrink is compensating for thermal expansion/contraction.  Once the part is solidified it is still going to shrink down as it cools.  For mild/low alloy steels this is generally about 1/4" per foot.  So if you want a 12" bar your pattern should be 12.25" long.  

Rigging is your gating and feeders (risers).  These need to be placed so that they are effective and relatively easy to remove and clean up the contacts.  Gating can be very important, but you are often limited based on geometry and molding method.  Basically you need to reduce turbulence as much as possible and keep in mind that the first metal in the gate will be the coolest, and the last will be the hottest.  You want directional solidification so you want your feeders to stay hotter longer than the rest of the part, and not isolate individual part sections as hot spots without a feeder.  So a wedge only needs 1 feeder, but something like a dumbbell need at least 2.  Alternatively, you can go without the optimal amount/placement of feeders and live with a little bit of shrink (voids) in your part.  This is very often a cost effective approach.  If it isn't a critical feature, don't waste time/effort/money on making it perfectly sound. 

All this has to be considered with your molding and pouring practice.  Which way is going to be up?  Can you mold with a horizontal parting line and pour vertically?  Are you going to do investment casting or sand?  What level of detail do you need?  Everything has to be considered together.  

 

On the whole, I do not recommend DIY steel casting unless you have worked your way up to it.  Casting takes a bit of effort to do right, and getting metal up to 3000F really just adds to the difficulty.  The other aspects like hot topping, degassing, inoculating, and other such things are pretty simple beyond that.  

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Thanks for the insight. 

I was kinda thinking something much simpler/rudimentary.

Like just some casting sand. Make a square imprint with a piece of square tubing an inch or so deep.

Then trying to pour a simple bar a 1//2 or so thick.....or even and inch. Just so I am not trying to hammer out a a puck.

I wouldnt probably go through the trouble for just my scrapes,my main goal would be to melt some bloomery or hearth steel....what ever the correct term is there.

Knowing me I would probably be wanting to experiment mixing in some 5160 scraps at some point.

 

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David Boye had cast dendritic steel blades made 30 odd years ago.  They did take a fair bit of cleanup a I recall.

 

Geoff

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"The worst day smithing is better than the best day working for someone else."

 

I said that.

 

If a thing is worth doing, it is worth doing badly.

- - -G. K. Chesterton

 

So, just for the record: the fact that it does work still should not be taken as definitive proof that you are not crazy.

 

Grant Sarver

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On 12/14/2022 at 10:03 AM, Kreg Whitehead said:

This spring I want to try my hand and making some iron bloomery......the add in of non carbon steel to make it high carbon.

Here are my suggestions for the simplest and least expensive way for you to start with the tools and equipment you already have, and some basic additions.

 

Check out this thread By Emiliano Carillo on the small refining hearth. This will get you some smaller products that you can proces on the forging equipment you already have with minimal expenitures on hearth and fuel.

 

For an example of the forging/finishing processes, check out this thread by JJ Simon.

 

When you get that process under control and want to expand the possibilities to multi-bar work, I suggest you spend some time reading this thread by Aiden CC.

 

 

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“So I'm lightin' out for the territory, ahead of the scared and the weak and the mean spirited, because Aunt Sally is fixin’ to adopt me and civilize me, and I can't stand it. I've been there before.”

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