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I Forge Iron

Is this why Cast Steet is not as good as Forged Steel?


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Hello folks, 

 

I have been reading posts here and other places where some guy will ask if he can (some how manage) to melt good steel and cast a good (anything). The answer is, for the most part as far as I can recall, that the melting and casting results in the wrong types grain pattern in the steel.

 

So am I correct in my understanding that it is the hot or cold rolling that makes the right grain pattern and there is only so much you can do with hardening and tempering?

 

Just so you know I am about as close to being able to melt and cast steel or iron as I am to turning lead in to gold so this is just me trying to understand.

 

thanks

Ernest 

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That's quite the generality. Not as good in what application? I don't see a lot of forged swage blocks around, but lots of nice cast steel ones. There are some mighty fine cast anvils as well...

Although those are no doubt beyond what individuals are making at home with their backyard foundry.

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Cast STEEL  is actually a fine performing material!!  It is NOT EASY to accomplish!!!  CERTAINLY NOT for backyard hobbyists!!  Cast IRON is a different material.  Much more simply done... though still beyond the reach of most backyard guys.  There are also several types/grades of cast IRON and MANY alloys of cast STEEL.  Whether hot or cold rolled makes only minor differences in the steel properties!  Many modern anvils are cast STEEL and very high quality performers!  This technology is too new to appear in anvils of earlier vintages.

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As I understand it, it's a multy fold problem, as a hobbiest, obtaining the consistant high heat (but not to high) to melt the steel, but not burn of the carbon, or intrudice atmospheric contaminants. Obtaining, or manufacturing equipment that will safely handle the molten steel, and actually safely porting it in to a mold. Molten aluminum is dangerous enugh. The consensus seams to be, the expense, skills needed and safty concerns one is money ahead to perchase a cast steel component, or fabricate/forge one.
In the world of marketing comparing apples to oranges is a valade way to sell a product. Forged iron and steel was the way to go when rought iron was the king and steel was its cousin, as the slag inclusians ment that a forged peice was much like a split out tool handle verses a sawn one ( the grain ran in the right direction) wile cutting out a peice was my so good as you ended up cutting across the grain and the peice might split/crack along the slag inclusions. In to days age, marketing uses this "knlowlege" that forged is better as a selling point. And comparing a forged crank shaft or piston rods to cast nodular iron one was a selling point for high performance engines. But to say that the forged part was better because it was forged vs cast was a fallacy, you cast nodular iron, wile it is more economical to forge steel to manufacuare a crank shaft vs casting a steel one.
And frankly steel starts out as cast billets thease days, and are rolled (forged) in to bars and plates, cold rolling dose work harden the serfaces, but as soon as we heat it that goes away.

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Sorry folks, this is one of the examples of me not expressing my self. I know cast steel is, well, steel and there is a reason that we have kept using it for so long and that is it works.

What I was thinking was people that want to cast steel swords and knives and cast steel anvils over forged steel anvils.

I know that trying to melt and cast steel is a VERY ADVANCED skill and not something that you want to try for the heck of it.

One good example is the Lord of the Rings saga. I have seen people post "can you make a sword like in LOTRs?" and the answer is yes-BUT you would not want to.

 

thanks all

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One of the problems I see of casting a steel sword is the enlarged grain growth from the casting process.   Also when one casts items there can be voids from cooling. and mis mached grain alignments, This may not be a problem with a anvil but even casting hammers to shape they get a good slam from a forging press.

 

When we cast into an ingot, it gets reduced to size and shape by forging/rolling, that does not happen when cast to final shape.  Simply an added benifit from forging is the smashing of the large grains into smaller ones, and the realignmentt of the grain structure.

 

I have been wrong before...

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With cast steel any forging or passes a rolling mill reduces the grain structure.  How much of that can be accomplished through the appropriate thermal cycling.  I have a pretty good idea of where you can end up in a knife,  but then that is a pretty small item vs an anvil.  Still  need to account for voids and flaws.  Kind of curious

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There are two types of casting that are much stronger than forged or otherwise formed metals: Monocrystaline and Amorphous.

 

Monocrystaline is, as the name implies, a casting where the metal is manipulated while cooling to form a single crystal throughout the entire piece. Turbine engine compressor and turbines are made this way, the whole thing is ONE big honking crystal. It's the crystal boundaries that act as initiators for material failure, call it grain growth if you wish. What you're looking at in a broken piece, all the shiny facets are crystal boundaries with the other side missing. They act just like a cold shut, I SHOULD say a cold shut acts like a crystal boundary, all the force on the piece is conducted to the fault in the form and concentrates there.

 

Amorphous castings are metal with NO crystal structure at all, zero and are in a completely different league from "normal" forms of the given metal. They're typically several x as strong with unbelievable good failure conditions. The only one I know (I think) for sure is they do NOT work harden, no grain (crystal structure) to grow.

 

Do it in a home shop? I'm going to give it a try as soon as I get the time machine debugged.

 

Frosty The Lucky.

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We cannot say that casting or forging is a superior method of production without first defining the goals or performance characteristics. Both methods will produce fantastic parts. The general way in which forgings tend to be superior to castings is in applications with fatigue loading such as large gears, axles, shafts etc. The reason for this is because during forming, the metal is forced to flow around corners/contours.This means that the properties (in particular ductility and impact strength) in forgings tend to be non-uniform. Castings do not have grain flow and therefore properties are the same in all directions. The directional nature of properties in forgings means that you can select the forging method to achieve the best possible properties for the application, while with castings, you don't have that advantage.

 

The other value to forgings, especially open die forgings, is that there are no pattern costs so for small quantity jobs, the cost of production may be lower so even though the properties of casting could be fine for the job, a forging is chosen due to lower cost. 

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May I humbly suggest:

- Metallurgy for the Non-Metallurgist, Second Edition(05306G) [Hardcover]

by ASM International, Arthur C. Reardon

http://www.amazon.com/dp/1615038213/ref=wl_it_dp_o_pC_S_ttl?_encoding=UTF8&colid=214TBF4SKG1OU&coliid=I3II46MYN6AS0E

 

Dave: OUCH! For those of us who can't afford to keep feeding our libraries would you please just tell me how far off base I was?

 

Give it to me straight Bro I can take it! <grin>

 

Frosty The Lucky.

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One of the problems I see of casting a steel sword is the enlarged grain growth from the casting process.   Also when one casts items there can be voids from cooling. and mis mached grain alignments, This may not be a problem with a anvil but even casting hammers to shape they get a good slam from a forging press.

 

When we cast into an ingot, it gets reduced to size and shape by forging/rolling, that does not happen when cast to final shape.  Simply an added benifit from forging is the smashing of the large grains into smaller ones, and the realignmentt of the grain structure.

 

I have been wrong before...

I love that term "good slam from a forging press". Well Done Sir!

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It was the alignment of the grain that I was foggy on. I had seen a post that someone used repeated thermal cycling to re-shape the grain but the alignment of the gain is the bit I was missing. This is why, from what I have read, the auto makers and other major steel consumers have been able to take steel and use rolling and shaping to make lighter, stronger and more durable everything from cars to cans over the last 150+ years. There is a book series called 1632 where people find them selves needing to make due with what is on hand and that reminded me of the advances in technology such as the rolling of steel.

 

These books are a great read provided you can suspend disbelief (at least I think you may need to) on some things such as a group of very motivated people making the necessary heating and tooling for a rolling mill to roll railroad track in to strips of armor plate with only the resources found in an average sized West Virginia coal mining town (post mine closing in the gone to seed phase of life) and 17th century Central Germany. 

 

The mining town is transported (mine and all) to Thuringia  where the towns people to what Americans do best, defend their way of life. 

The United Mine-workers of America vs the Holy Roman Empire!

 

http://en.wikipedia.org/wiki/1632_(novel) read free at the publishers site http://www.baenebooks.com/p-379-1632.aspx 

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