Jump to content
Alex W.

I'm making a foundry for casting stainless steel, and I need a few answers on a few questions.

Recommended Posts

(I Guess it's a lot more than a few, but I have the easiest in the beginning, and that's a reasonable amount.  The rest is a bit harder, as I suspect it all to be experience based, and I understand if you don't want to or can't, but anyway, hope you enjoy it in some way.)

 

First, if there ever was an ideal increase of temperature from melting point of any steel alloy for casting it, how much of a difference is that?  And is that going to be same for all alloys across the melting point temp graph?  I should point out that I'm casting a 1 or 2" cylinder for a density set(constant weight and diameter, but length and material varies), so I'm probably good with only accounting for outside of the foundry time, which may be slightly longer in my case, but I really don't know how much waiting time or cylindrical molds are gonna alter how hot I make it.

  
Second, 
   I thought I wasn't going to be melting iron in a foundry, and therefore, I only ordered 2300F kaowool, but I am able to line it with (hopefully insulative or no go) 3000F firebricks my friend has, up to an inch and a half thick, and maybe more.  Is it ok if I melt iron then?  The same kaowool will also be covering a kastolite 30 lid about 3" thick, so...  If you guys are a little overwhelmed with the explosion of details here, I understand if you can't answer anything, but just for the chance, here I am.  Thank you for reading all of that.  

 

But one more thing, I am planning on using a couple of u bolts as handles in that lid I mentioned up there.  Is it okay in a lid like that, or is it gonna expand and crack it?  I plan on at least an inch of kastolite in the way, so I hope it doesn't melt, but it is going about 3kF, so idk, I might have to use a wonky Dutch oven looking tool, or something, but I'll be fine either way.  

But anyway, if you all are able to understand what I'm describing, I'd love to hear your input, and any other advice you have for me if you can, and I hope to return the favor in some way.  And as always thanks for reading, and have a good day.

Share this post


Link to post
Share on other sites

First of all alloying will decrease the melting point of the steel as compared to iron.  The exact melting point will be governed by  the exact alloy

 

Another thing to consider is that investment material, the stuff that you make the mold from, is not the same thing that you would use for casting cupric alloys, gold, or silver.  It's rated at a higher temperature and it may be harder to find (nope, see below).  It's been a long time since I've priced any investment mix, it comes in a powered form, but when I did find any investment mixes rated for the temperature that you'd be operating at it came in large barrels.  Like 50-100 pounds. (nope, see below)

 

Any crucibles that you need to melt the stainless steel in might need to be higher rated than those needed for cupric alloys or gold and silver and I imagine that they would run more in cost.

 

If you haven't read up on casting get some books and do so then, when you have everything  plotted out build the furnace to melt steel in.

 

Doug

 

Ok, as an afterthought I look investment material up on the web and I ran into two products.  One is Pro-HT Steel that is designed for jewelers who make stainless steel jewelry.  It appears that it comes in smaller bags than what I used to see probably over 10 years ago.  Another is Omega investment powder.  The add didn't have a lot of information but it did say it was rated for higher temperature.

 

I'll still stick with  my advice that you work out all the issues with casting steel, like the furnace, crucibles, tools for handling glowing yellow crucibles full of molten steel, burn out ovens and tools for mixing investment, which might include a vacuum chamber.  Then and only then build your furnace/foundry to melt the steel.

 

I'm a little slow tonight but if all you want to is cast cylinders you might want to look up sand casting.  The cope and drag (the frame that holds the sand for compacting and casting are easy to build.

Edited by Doug Lester
another light bulb came on
  • Like 1

Share this post


Link to post
Share on other sites

A long way to go.  The protective equipment needed is expensive and critical to your safety.  A drop of moisture in your mold at the wrong time can flash to steam, expand and send molten metal shooting out in all directions.

 

If all you want to make is cylinders, why not just purchase the steel bar stock and machine it to size?

  • Like 1

Share this post


Link to post
Share on other sites

Dan has a good point.  Even if you cast the cylinders you will probably have to cast a little over sized to allow for shrinking and then machine the cast cylinders down to the finished size that you want.

 

Doug

  • Like 1

Share this post


Link to post
Share on other sites

I didn't see this until today.  I've been a metallurgist in foundries making steel and iron castings (and a little brass and nickel base) for over a decade.  There are a lot of things that need to be thought out.  Pouring temperatures are highly alloy AND geometry dependent, and are going to be very important to getting a quality casting.  Shrink rate is going to be pretty important, and most steels are going to be around 1/4" per foot.  But this also has geometry considerations.  You also have to plan for centerline shrink and solidification paths in general.  More information on what your goal is would be helpful, as then we could better steer you to the right process.  It sounds like you are going to want to heat the metal up to at least 3000 F, but possibly more depending on your set-up.  It is going to take a lot of work to get a set-up that will melt that well.  Stainless also likes to create a slag that is a bit like molasses (granted, I have a lot more experience with slag than molasses).  For small scale casting, I would probably wear the same PPE as I would for forging (probably with heavier welding gloves), and wouldn't be all that concerned as far as extra safety precautions go.  But I know what I am doing.  It is hard to say what is not obvious to others which seems obvious to me.  

  • Like 1

Share this post


Link to post
Share on other sites
33 minutes ago, Jerrod Miller said:

But I know what I am doing.

 

Exactly. 

 

I'm pretty complacent about playing with molten glass after a similar period of time working with it professionally, but that is only at around 2,100 deg. F and much more viscous and with lower thermal transfer characteristics and thermal mass than molten steel.  Still I've been surprised by some glass working operations.  There is a Venetian technique I once saw demonstrated for making a translucent "bubble glass" ( I forget the Italian term for that).  In any case, the master doing the demonstration filled a 6" steel pipe cap casting ladle with gasoline then plunged it into the glass furnace with a molten tank of glass at around 2,300 deg. F and stirred it vigorously into the pot of glass.  Fantastic technique, but I was standing by the door ready to race away from the building the whole time.

 

Just saying that there are tricks of the trade that may not be obvious to the uninitiated.

  • Like 1

Share this post


Link to post
Share on other sites

I have a hobby foundry myself and as Jerrod said, there are variables to contend with and safety issues

that are common sense, and subtle ones that can catch you off guard and really frig up your day or your life !!

Study up on it and if you can, find a hobby melter close by  who may show you the process.......................B)

  • Like 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...