Author Topic: Cast iron ''SPRUES'' can they be of use to the model machinist?  (Read 15253 times)

Offline kellswaterri

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Hi all,
visited our local Railway Museum Engineering workshops today...after a wander around and a bit of a chat I left with a fairly large and heavy bag of bits of bronze and cast iron...the cast iron was the cut off ''SPRUES'' from castings done in the workshop foundry...I intend to give them a try after first giving them a good going over with an angle grinder...what do you guys think?
John.

Offline chucketn

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #1 on: August 12, 2013, 07:14:59 PM »
They could be a grat source of cast iron for pistons and the like for small engines...
Are they good quality under the skin? How big are they?

Chuck

Offline kellswaterri

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #2 on: August 12, 2013, 07:40:26 PM »

Hi Chuck, some about the size of a large orange, some of apple size, they all have an attached leg of 3/4'' diam.I will be giving them a going over with the angle grinder before I try to cut them...heres hoping :noidea:

Offline spuddevans

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #3 on: August 12, 2013, 09:30:01 PM »
what do you guys think?

I think that they will be absolutely useless, you should immediately package them up and send them to me for safe disposal  :Lol: :Lol: :Lol:


Tim
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Offline tangler

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #4 on: August 12, 2013, 09:36:42 PM »
Sprues, being the connection of the casting to the outside world, will be the first bits to solidify so there is a chance that they have chilled and will be hard but otherwise they should be the same quality as the rest of the casting except perhaps for some dross on the surface exposed to the air.  What a nice gift. 
Cheers
Rod

Offline ths

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #5 on: August 12, 2013, 11:52:01 PM »
I'd expect chilling at the 'outside' end of the spruce. Begin machining from the 'inner' end, you'll soon find out how much is usable.

Hugh.

Offline b.lindsey

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #6 on: August 12, 2013, 11:55:04 PM »
John...given their size and shape, what are tiy hoping to machine from them? Just curious.

Bill

Offline Maryak

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #7 on: August 13, 2013, 01:22:49 AM »
Hi John,

I built a mill engine using sprues and cast offs for the main parts, (cylinder, base, valve chest, piston). One thing they are not good for is piston rings.

If you want the best result machine off the hard skin and then let them rust away in a corner for a while to age them.

Best Regards
Bob
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Offline b.lindsey

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #8 on: August 13, 2013, 01:50:40 AM »
Bob, I know we joke some about castings "aging" under the workbench, etc., and I understand what you mean about machining the hard outer skin off...but what exactly is the science behind letting a cast piece of iron age?  What does it actually do to the metal by allowing it to oxidize?

Bill

Online Dan Rowe

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #9 on: August 13, 2013, 02:35:00 AM »
They take a skim cut on the Sulzer diesel cylinder liners for the same reason and set them in the back field for a year or so. This normalizes the the stress in the casting before machining the liner to finish dimensions.

Dan
« Last Edit: August 13, 2013, 02:41:24 AM by Dan Rowe »
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Offline Maryak

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #10 on: August 13, 2013, 02:45:22 AM »
Hi Bill,

It's my understanding that aging cast iron castings is for stress relief of the metal brought about by the casting process. Heat treatment is another option to achieve the same thing but requires equipment not normally found in a home workshop. i.e. something to bring it to 600C and hold it there for a while to ensure all of it is at that temperature and most importantly allow it to cool down evenly. Usually done by allowing it to cool inside the furnace as the furnace cools down.

For the hobby machinist chucking it under the bench for a year or so is a much cheaper and easier process.

Best Regards
Bob
Если вы у Тетушки были яйца, она была бы Дядюшкой

Offline derekwarner

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #11 on: August 13, 2013, 06:10:13 AM »
From an OZ trained old school point of view.....

1. A sprue riser tube diameter irrespective of ?? length is calculated relative to the mass of the casting in question
2. The cooling rate in the sprue will have been greater that the mass of the casting
3. Irrespective of the quality of the iron blend.........the differential [chilled] cooling effect will have altered the structure of the iron in the sprue riser
4. One would suspect skin effect hardness as others have noted, you may also find greater carbon under the skin

Burying them in the back yard [as messes Rolls & Royce did with cast iron engine blocks] :naughty: will not change the metallurgical composition of the iron....again it will simply dull [normalise]  the in cast stresses created at the initial cooling post casting.............Derek
« Last Edit: August 13, 2013, 06:38:55 AM by derekwarner_decoy »
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Offline Jo

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #12 on: August 13, 2013, 08:00:42 AM »
Heat treatment is another option to achieve the same thing but requires equipment not normally found in a home workshop. i.e. something to bring it to 600C and hold it there for a while to ensure all of it is at that temperature and most importantly allow it to cool down evenly. Usually done by allowing it to cool inside the furnace as the furnace cools down.

Sticking it in the centre of a bonfire can work, and provides a long cooling time. ;)

Jo
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Offline Maryak

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #13 on: August 13, 2013, 08:36:26 AM »

Sticking it in the centre of a bonfire can work, and provides a long cooling time. ;)

Jo

As Mr Fawkes would say all of us Guys bow to the feminine touch.  :ThumbsUp:

Best Regards
Bob
Если вы у Тетушки были яйца, она была бы Дядюшкой

Offline kellswaterri

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #14 on: August 13, 2013, 12:02:22 PM »

Hi folks,
            thank you all for your comments, as Tel would say...thats a gnarly one or two or... now I know why there was a large heap of them lying outside the shop...I will try and clean up some of the shanks first, they could be used for piston material...the larger bits,I will have to Glare at them while I have a cup of coffee, the glare might be enough to make them behave.

Offline MuellerNick

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #15 on: August 13, 2013, 01:47:44 PM »
Quote
What does it actually do to the metal by allowing it to oxidize?


It does nothing. Absolutely nothing. Except waste time and some "Oh! Wow!" from those who believe tell-tales.


Internal stresses in a casting are gone after a week. The fastest decline is within a few hours.


Yes, there are stories, that BMW, during their F1 engagement during the turbo area, bought old castings. And that they buried them and that they peed on them. And whatever. Just to build some mysteries around their success. Others do that too.


Nick

Offline derekwarner

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #16 on: August 14, 2013, 12:41:09 AM »
mmmmmm...strapping a casting down to a steel plate in the back of a truck & take the plate for a 50km ride on a bumpy road  :cartwheel:  :ROFL: will progress the stress relieving  function ....Derek
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Offline firehazard

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #17 on: August 14, 2013, 12:33:32 PM »
Hi,

it is my understanding that there are two different reasons to heat treat iron castings.

Stress relief and machinability.

Stress relief treatment is kept below 550 degrees C and the old rule is one hour for every inch of thickness followed by a slow cool down.

To improve machinability heat to 800 degrees C quickly and a slow cool down. This will break down the carbides but sadly reduces the strength and hardness of the iron.

"Modern Foundry Practice" which seems to be from the late forties is a good book if you can find it.

take care

John

Offline Ian S C

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #18 on: August 14, 2013, 02:47:29 PM »
The manager of the retail shop that I bought my Taiwanese lathe from had just returned from the factory in Taiwan, and he was telling me about it, out in the yard were piles of castings ageing, one large stack labelled Colchester England,  He asked the factory manager about these, and was told that they stayed there 5 years,  I think their own castings around 3yrs.  the Colchester stuff was lathe beds.  The castings were partly machined.     Ian S C

Offline MuellerNick

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #19 on: August 14, 2013, 03:14:19 PM »
I highly suggest reading this PDF: http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=AD0620556
If someone has a research (and not just wild claims by hearsay), I'd like to read it. Even if it shows the contrary.


Nick

Offline tel

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #20 on: August 14, 2013, 09:49:27 PM »
Well, regardless of whether it works or not, it was most certainly the practice of the car manufacturers here - I have seen the (row upon row upon row of) castings sitting out weathering myself, aat more than one plant. These days I believe they use an artificial aging process.
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Online Dan Rowe

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #21 on: August 14, 2013, 10:07:53 PM »
Nick,
I did read that paper several days ago. It does not mention the method that both Bob and I mentioned and that is to take a SURFACE cut and leave the casting to age out doors. In Bob's case he did say under the bench.

I checked my marine engineering books and the internet and I can not locate a source of that method so I must have gotten the information from a Sulzer field service rep. So that does make it hearsay but now at least 3 folks or more have mentioned partially machined castings in a field so this is or was common practice for some operations.

Dan
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Offline ths

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #22 on: August 14, 2013, 10:18:38 PM »
I don't think that there's anything magic about 'outdoors', it's just cheaper than building an 'indoors'.

Online Dan Rowe

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #23 on: August 14, 2013, 10:38:39 PM »
The paper referenced by Nick does have a test of heating and cooling cycles with dry ice and then heating to 2200F for four cycles which had a very small improvement but the casting was not given a surface cut before the cooling/heating cycles.

The castings I was talking about are large cylinder liners that is 900mm bore and 1550mm stroke so yes it is a cheaper solution to use an empty field than to build another building.

Dan
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Offline Maryak

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #24 on: August 15, 2013, 12:32:18 AM »
Hi Guys,

Without getting at all technical...............no major company seeking to maximise their profit margin is going to adopt a process which is not going to give a positive benefit, be it buying a field, producing parts 5 years in advance of them being required; etc.

For the technically minded.

http://www1.eere.energy.gov/manufacturing/resources/metalcasting/pdfs/age_strengthening.pdf

Best Regards
Bob
« Last Edit: August 15, 2013, 02:25:07 AM by Maryak »
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Offline firehazard

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #25 on: August 15, 2013, 01:15:33 AM »
Hi,

that was a very interesting paper.

This discussion has strayed quite a long way from the initial question.

If I was pouring a component for serious use I would not use straight grey iron. Just 1% nickel in the mix makes a huge difference. I suspect the components people have observed, or just been told about may not be plain old grey iron.

The famous "Meehanite" people have been modifying cast iron and its properties for a good while but they don't tell all they know.

"High Duty" iron is not the same thing at all as plain grey iron and there is an extensive body of literature dealing with the possibilities. As well as the proprietary recipies of the Meehanite people and many others. Including engine manufacturers.

Precipitation hardening is not just confined to aluminium and its alloys.

Take care

John







Offline MuellerNick

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #26 on: August 15, 2013, 06:51:55 AM »
So, there do happen two things:
Stress relief and strengthening. Both occur within 10 days.


If you have roughed a cast part, put it anywhere for a week and then do finish machining.
But it is absolutely impractical to completely grind off the outer skin of say a lathe-bed or an engine block.


Age hardening of aluminium alloys is a well researched and documented process. But also, it is a quite different alloy than cast iron.


Nick

Offline kellswaterri

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #27 on: August 15, 2013, 11:00:21 AM »
   Crikey!!! some thing new learned every day...I will take a little from each post and proceed to my shed...
                                                            Thanks all,
                                                                      John.

Offline steamer

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #28 on: August 15, 2013, 11:01:53 AM »
Gentlemen,

I have seen both methods used before in real life...hell by the same company!  Heald Machine.

New castings had the following notes on them if they were "Iron"

First.....NEVER EVER ask for "Cast Iron"....or you will get it!.....I seem to remember watching a 42" faceplate being turned and blowing up tools....When we investigated, you could see the outline of a railroad spike in the casting!....and that is what it was...and hard as glass too!

We would specify Meehanite GC-40
Meehanite is a process by which the iron was produced.  All that says is if you get iron to that specification, you will get the quality you want in a machine tool.
The GC-40 designation was Grey cast iron with a 40000 psi minimum tensile yield

The next note was the money shot though.

"Stress relieve to 220 BHN +/- 20%".....I remember that very clearly. and it was drilled into my head by the "Gray Beards"

Now if it was stress relieved, it was generally per the document that Nick is referring to, I remember it was at 1100 for one hour.    HOWEVER

We had a bunch of Meehanite machine bases for Heald 272A's sitting in the back lot stacked up for "seasoning".....well that's all well and good...but I seem to remember occasionally the floor having a problem them moving around during machining...not all...just some.

We also had a vibratory stress relieving machine rig....I even watched a machine base dropped from a crane on to the floor because it would "knock" the stress out......

I think if you have really good material, poured by someone who knows what they are doing, the stresses will be low to begin with.
Otherwise, I would use the navy recommendations.

JMHO.......your mileage may vary....professional driver on closed course........yada yada yada

Dave
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Offline steamer

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #29 on: August 15, 2013, 11:16:00 AM »
Additionally, Nick, I know I've bumped a straight edge and watched it curl up...and following the "generally accepted" practice of letting it "rest" over night have the curl come back  out

NO I can not explain that...but I am not the only one who has observed that either

As to getting the "skin" off....if the surface is in a chilled state, and hard, then a lot of stress will be relieved once it is cut off...but from the surface...not  necessarily from deep inside the part.

At that point it's a question of how thick the sections are..how it was processed and handled...I would say you may have better luck with the lottery than guessing the stress state of the casting in this condition.....I wouldn't want to build an important part of a machine tool or an engine with it.


Which nicely gets us back on topic now doesn't it...perhaps we should save our sheckles for good material to make important parts out of ...hmmmm?
 8)
Dave
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Offline Jo

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #30 on: August 15, 2013, 11:41:39 AM »
Which reminds me I must put those two old sash weights in the bottom of the bonfire before I light it  :naughty:.

Jo
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Offline tel

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #31 on: August 15, 2013, 11:45:38 AM »
 :Lol: I'm a bit of a fan of sash weights - you get the odd unworkable one, but most are far better stuff than people are led to believe.
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Online Dan Rowe

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #32 on: August 15, 2013, 02:55:11 PM »
Bob,
I see you slipped in a technical paper on ageing cast iron. Here is a brief overview of the same research.
http://www.e-smarrt.org/factsheets/aging_graphite.pdf

Dan
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Offline steamer

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #33 on: August 15, 2013, 04:11:14 PM »
Thanks for pointing that out Dan, I didn't spot it before....Sorry Bob.

I'll read it tonight

Dave
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Offline steamer

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #34 on: August 15, 2013, 11:44:25 PM »
Dan,

The age strengthening shown in the project proposal you attached shows a rise in tensile strength of Gray cast iron from 255 MPa to 275Mpa.
The strengthening was to be studied as part of a ongoing research project  as it appears that this was a proposal document for this research.

I did not see any statement regarding surface hardness, though they do claim that machinability was improved...but it did not state by how much.  However, the change in strength is not particularly large from a practical perspective...as parts are very rarely designed to tensile strength or even yield, but to a small fraction of the yield.  An exception to this would be a shear pin perhaps.

The rise in tensile strength is equivalent to a tensile strength improvement from 37000 psi to 40000 psi over a period of approximately 1000 hours. 
Dave
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Offline steamer

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #35 on: August 16, 2013, 12:22:35 AM »
Hi Guys,

Without getting at all technical...............no major company seeking to maximise their profit margin is going to adopt a process which is not going to give a positive benefit, be it buying a field, producing parts 5 years in advance of them being required; etc.

For the technically minded.

http://www1.eere.energy.gov/manufacturing/resources/metalcasting/pdfs/age_strengthening.pdf

Best Regards
Bob

Hi Bob,

I did read your attached paper.   The observations were consistent with my own experience and "lore".  I have been told that the carbon will precipitate and be dispersed in solution over time.   I am astonished by the data showing a large improvement in machinability.   The strength improvement is as was described in the paper Dan described.    I didn't see any discussion of experimental error assessment.   

Your Friend

Dave
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Offline MuellerNick

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #36 on: August 16, 2013, 07:58:41 AM »
Quote
I have been told that the carbon will precipitate and be dispersed in solution over time.


No. In cast iron, the graphite is either spherical (GJS) or laminar (GJL). It is a wanted property that the carbon aggregates. Also, we have worm-shaped carbon (vermicular), called GJV.
The carbon lowers the melting temperature, that's a wanted property. It also increases the dampening, that's why CI is preferred for machinery.
Adding alloys influences the shape of the carbon "blobs".


Nick

Offline steamer

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Offline Bezalel

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #38 on: August 20, 2013, 01:22:03 PM »
Trim>
The carbon lowers the melting temperature, that's a wanted property.
<trim

Hi Nick
 
The Iron Carbon phase diagram seems to contradict that statement.
I prefer to think of it as the right amount of carbon reduces the melting temperature of the alloy.

The Iron Carbon Alloy becomes Eutectic at 4.3% Carbon w/w . An Iron Carbon alloy with just 1% more carbon actually increases the melting temperature.

At 5.4% C w/w the alloy is not a liquid until it reaches a temperature grater than 1600 C.   Pure Iron becomes liquid at 1538 C.

Bez

« Last Edit: August 20, 2013, 01:33:36 PM by Bezalel »
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Offline firehazard

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #39 on: August 21, 2013, 01:09:35 AM »
Hi,

that's a very interesting diagram for those of us who don't have access to a cupola.

thanks

John

Offline MuellerNick

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #40 on: August 21, 2013, 11:48:38 AM »
Quote
The Iron Carbon phase diagram seems to contradict that statement.


Not that much.
Not so much, because carbon steels stops at 2.06% of carbon. Not so much, because the diagram is misleading. Right of the eutectic, the solid line going upwards is NOT where you have molten metal. The dashed line that stops at 1253 C and the solid horizontal line is liquid too.


"L + C(graphite) is liquid plus primary Fe3C.
The section (roughly) lined out by 0.16, 2.1 and 4.2 is liquid too (liquid + gamma-mc (mixed crystals)).
So above 2.06 % C, you have won and a constant melting temperature of 1153 C.




Nick

Offline firehazard

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #41 on: August 22, 2013, 01:18:04 AM »
Hi,

it might be worth mentioning that 4% carbon is regarded as the practical maximum of carbon solubility in iron. You would need to be doing something a bit special to exceed that.

The problem for small scale casting is getting enough carbon into the metal.

I have personally smashed up modern engine blocks with a sledgehammer and, unlike classical grey iron, a Ford or VW block will bend before it breaks.

take care

John


Offline Bezalel

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #42 on: August 24, 2013, 06:31:39 PM »
Quote
The Iron Carbon phase diagram seems to contradict that statement.


Not that much.
Not so much, because carbon steels stops at 2.06% of carbon. Not so much, because the diagram is misleading. Right of the eutectic, the solid line going upwards is NOT where you have molten metal. The dashed line that stops at 1253 C and the solid horizontal line is liquid too.


"L + C(graphite) is liquid plus primary Fe3C.
The section (roughly) lined out by 0.16, 2.1 and 4.2 is liquid too (liquid + gamma-mc (mixed crystals)).
So above 2.06 % C, you have won and a constant melting temperature of 1153 C.




Nick

Hi Nick

That's an very interesting way to interpret a binary phase diagram.

I'll explain for those not familiar with them a few aspects of the PD.

Since the other one was misleading  here is one from a different university.



Each line represents the temperature at which the rate of temperature change stops momentarily during heating or cooling due to latent heat.

This equates to the energy absorbed or released during a change of state or crystal structure.   

The top line from 1535oC through E to 1837oC is known as the liquidus. above which the alloy is termed a liquid solution i.e it is a liquid.
Latent heat is released as the metal cools at this temperature solid crystals form. In many alloys not all the metal will solidify at that temperature. 

The solidus line is a line below which the alloy is a solid which here runs from C to B through E at 1130oC

Between those two lines it is known as a solid solution,  because contains solids at that temperature.

A solid solution is NOT a liquid.

Solubility of carbon in iron is very temperature dependent and you can use heat treatment to change the numbers below via quenching, tempering or annealing. But in general;

At room temperature ( assume very slow cooling to establish Body Centered Cubic crystal formation- alpha Iron) solubility of carbon in Iron is  around 0.008%

At 723oC solubility of carbon in Iron is around 0.022% ( assume very slow cooling Body Centered Cubic crystal- alpha Iron)
At 723oC solubility of carbon in Iron is  around 0.83% ( Face Centered Cubic crystal- gamma Iron)
At 1130oC solubility of carbon in Iron is  around 2.2% ( Face Centered Cubic crystal- gamma Iron)

Solubility of Carbon in Iron as Fe3C is  around 6.7%

John
I know all this hasn't answered your original question,

So IMHO the answer is....... If the sprues machine nice, use them...  if they don't, toss em out.
Depending on what the castings were for, that the sprues came off, they could be made of who knows what.

Bez
« Last Edit: August 24, 2013, 06:37:17 PM by Bezalel »
Queensland - wet one day, humid the next

Offline Jo

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #43 on: August 24, 2013, 06:48:28 PM »
All of these numbers are a bit technical for me busy relaxing at home... All I can say is the latest two sash weight have been recovered from the ashes of the bonfire and they cut on the mechanical hacksaw like butter  8)

Which is some what different from when they started  :facepalm2:

Jo
Usus est optimum magister

Offline Bezalel

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #44 on: August 25, 2013, 12:32:53 AM »


Sumarises it nicely Jo.

Probably all John wanted to know. 

I wasn't expecting to hear back on the annealing in a bonfire plan until after November 5.

Who needs a TTT chart?
 :cheers:
Queensland - wet one day, humid the next

Offline MuellerNick

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #45 on: August 25, 2013, 11:04:02 AM »

I don't think I have to translate "liquidus" and "solidus", even if it is Latin.

First, we have to understand binary eutectic alloys (see picture 1):


We have a liquidus-line. Above that, everything is liquid.
We have a solidus-line. Below that, everything is solid.
So area (1) is completely liquid.
Area (3) is completely solid.
At the eutectic point, the alloy changes completely from solid to liquid.


Now what's on in the areas (2)?
Here, we have a mix of solids and liquids. In a binary system (components A and B), the further we are away from the eutecticum, the more solids of component A or B we have "swimming" in the liquid. This is the superfluous component to get a perfect eutectic alloy.


Now, if we look at picture two:
This is a oversimplified Fe-C diagram. It is only useful right of the 4%-point. The important point is, that it doesn't stop at 10% C, it goes all the way up to 100% C (quite useless from the POV that we want a cast-able iron).
But if you accept that the area (2) of the first picture contains a mix of solids and liquids, we see that at 10% carbon content, 6% are solid Fe3C. These Fe3C are small crystals, no big blobs or whatever that considerably change the viscosity.


Nick

Offline tel

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #46 on: August 25, 2013, 12:06:37 PM »
All of these numbers are a bit technical for me busy relaxing at home... All I can say is the latest two sash weight have been recovered from the ashes of the bonfire and they cut on the mechanical hacksaw like butter  8)

Which is some what different from when they started  :facepalm2:

Jo

I'm with you Jo - the original question was quite simple, and the simple answer is/was 'perhaps' but it seems to have run away from that.
The older I get, the better I was.
Lacerta es reptiles quisnam mos non exsisto accuso nusquam

Offline Bezalel

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #47 on: August 25, 2013, 12:27:45 PM »
Good point Tel

I went back and re-read the original question which was;


what do you guys think?

John.

So now you know...... some of us think way toooooo much   :lolb:

Bez
Queensland - wet one day, humid the next

Offline kellswaterri

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #48 on: August 25, 2013, 12:59:16 PM »
I seem to have created a ''Monster''
                     Frank N. Stein...aka
                                     John
Brilliant debate.......

Offline tel

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Re: Cast iron ''SPRUES'' can they be of use to the model machinist?
« Reply #49 on: August 26, 2013, 09:46:45 AM »
Yeah, but they don't always take de bait!  ;)
The older I get, the better I was.
Lacerta es reptiles quisnam mos non exsisto accuso nusquam