Density of molten (stainless) steel? 2

[rd400guy]

In the steel industry, we generally use 0.26 pounds per cubic inch as the density of molten steel. After designing a prototype mold and casting a few ingots using it, it has become apparent that 0.26 pci is not the correct density.

Specifically, we're casting stainless steels (T-304L, T-303+, and T-316L) and tool steels (A2, D2, and H13), and we're consistently getting actual ingot weights that are less than the theoretical ingot weight. So my question:

Does anyone know of a reference that lists reliable molten steel density? I can find liquid density of elements, and I'm willing to believe that 0.26 pci is accurate for mild steel, but for highly alloyed steels, I need more precise numbers. Thanks in advance.

 

[mcguire]

The density of 304 and 316 at room temperature are listed at 0.29 pci in the Handbook of Stainless Steel. I don't know of any source of the density of these alloys in the molten state.
I would check foundry societies or handbooks since this information is critical for foundy pattern making.

 

[metengr]

Here is a web site from Auburn U that shows the change in density as a function of temperature (1600 deg C) for a CF8M (316 ss) stainless steel;

metalcasting.auburn.edu/data/CF8M_Stainless_Steel/CF8MSS.html

 

[EdStainless]

Everyone that I know in the biz has their own correction factors, based on their own casting practice. And they don't share.
You have mold sizes and ingot weights, work your own up. I am sure that you could use the same factor for any 3XX series stainless.
I would expect a fair amount of variation between tool steel grades though, since their compositions are so different.

= = = = = = = = = = = = = = = = = = = =
Corrosion never sleeps, but it can be managed.

http://www.trenttube.com/Trent/tech_form.htm

 

[BillPSU]

You've got several problems when you are comparing molten steel of any variety with the ingot weight. First depending on the superheat of the melt the density will change due to increased volumetric expansion. Secondly unless you are vacuum pouring the ingot the iron is trying to oxidize and iron oxide weighs less than iron. Third you will experience shrink in the ingot where density will be less than expected.
I agree with EdStainless there are correction factors in the industry however in the casting industry the weight of the casting includes the weight of the gating system and the risers. The risers is where the shrink occurs (hopefully) in castings.

 

[metengr]

I was able to locate information on the change in density as a function of temperature for carbon steel (1026) and iron.

For iron, the density at the liquidus temperature (1536 deg C) is reported to be 7022 kg per m^3. At a superheat of 1727 deg C, the density decreases to 6866 kg per m^3.

For AISI Type 1026 carbon steel, at 1027 deg C the density is 7550 kg per m^3. For comparison purposes, iron at 1127 deg C has a density of 7515 kg per m^3. It appears that the iron and steel density changes behave in similar fashion, so if you have complete temperature versus density data for iron that could be used to approximate the density changes for steel/low alloy steel,as well.

The data reported above was from "Transport Phenomena in Materials Processing" by Poirier and Geiger.