I have some questions

[Bustaballs]

Hello!

I was having trouble finding the information I was looking for and I figured a master weapon or bladesmith could assist me. I have a few questions that might seem a bit odd.


If you were to take a chunk of steel, put it in a fire until it reached melting point, then set it down somewhere in a room that is room temperature, how long would it take to cool?

How long would it take to cool if it was buried under rubble?

Does it matter how large the piece of steel is? If so, about how long would it take for a piece of steel to cool that is 20 feet tall and 3 feet wide on all sides? Just an estimate is fine.

I'm sorry about the strange questions but I can't find an answer anywhere else.

 

[patrickjames]

your serious?
pj

 

[Gollnick]

If you were to take a chunk of steel, put it in a fire until it reached melting point, then set it down somewhere in a room that is room temperature, how long would it take to cool?

That would depend on a lot of factors such as how large the "chunk" of steel is. What container it's in. Air movement, etc. When you talk about melting steel, you are talking about a lot of heat.

Most knifemakers never actually melt steel. They buy a piece that is fairly close to the final dimensions they're working toward and then they either heat it to a point where it's maulable, which is well below melting, and then they form it typically by hammering. This process is called forging. Or, they remove materials with some combination of sawing, grinding, filing, etc. This process is called "stock removal."

As a result, knifemakers are not likely to have first-hand experience with handling liquid steel.

How long would it take to cool if it was buried under rubble?

That question is way to vague. It depends entirely on what the "rubble" is made of. It could take either more or less time depending on what the "rubble" is.

Does it matter how large the piece of steel is? If so, about how long would it take for a piece of steel to cool that is 20 feet tall and 3 feet wide on all sides? Just an estimate is fine.

That is a huge piece. That is larger (twice at least) than the ingots that steel mills pour. Those take many days to cool. But, efforts are deliberately made to keep them from cooling too quickly lest cracks develop.

Keep in mind, also, that when substances change phase, go from being liquid to solid, there is phase-change energy involved too. We often neglect that. But when you're talkin about 180 cubic feet of a complex metal alloy, that can not be neglected. When you're talking about 180 cubic feet of material cooling from thousands of degrees (which is how hot liquid steel is), nothing can be neglected because even a few percent error will throw your result off by days.

Just as a first-cut estimate, your answer will be in days, possibly tens of them.

 

[T. Erdelyi]

Chuck, when the telephone solicitors get you on the phone you string 'em along don't ya?

How long was the longest ya ever kept one goin'?

 

[Bustaballs]

Ah. Well let's say it's a piece of steel that is 3x3x3 feet. It's set into a fire until it reaches 800*C. It's then taken out and set on a dirt floor in a average room temperature with no wind and no container.

Then let's say the rubble consists of other steel chunks (some molten) and very fine dust.

Is it possible to get an estimate for that?

 

[orthogonal1]

Yeah, you can estimate it.

Just breeze on over to the google search, search "heat transfer" and "thermodynamics", get the basic equations.

Need to get the radiant heat rate of steel (one is about as good as another for estimation) at various phases, the mass of steel, etc.

I'd use my books, but they are in storage at this time.

Oh, yeah, pay attention to units. Btu versus Kcal, etc. Don't mix without appropriatte conversion factors.