sonic difference between cast iron and cast steel. No ringing sound in case of cast iron but cast steel has ringing sound. This is due to damping capacity in cast iron.
DEnsity differences exist between cast iron and cast steel. Cast iron should be near about 7gm/cc.while cast steel will be 7.8gm/cc.
If you took one solid plate of cast steel and one solid plate of cast iron and laid them side by side, you really couldn't tell the difference between them with just a visual comparison.
arunmrao
If you are talking about gray cast iron there is no ringing sound but if it is ductile iron you will have a ringing sound. Spark testing would be a reasonable method for differentation of steel from cast iron.
I referred to gray iron as cast iron. Sorry that is the practice here. Ductile iron is specifically called as such or SG iron(more popular term here. Sorry if i have confused.
Others with more knowledge may be able to expand on this or argue against it, but I think at least in some cases it would be possible to distinguish cast iron from cast steel visually, if one could observe a fractured surface. Perhaps in your case none are present, but other visual clues would include any identification markings, such as ASTM numbers. A48 is a common grade of gray cast iron while A27 would indicate cast steel. Of course there are many other designations. Could there be clues from the size / shape of the part? I don't know the answer I'm asking.
arcer;
Yes, you are correct in a way, if you had fracture surfaces to compare. However, if you really wanted to distinguish between either material, the best approach would be to perform field metallography or obtain a replica and evaluate the microstructure. These are nondestructive methods.
Instead of looking take a small sharp chisel and find an edge and start chiseling. The cast steel will peel off in nice chip (ductile) while the cast iron will break and make a porous little piece of chip (brittle).
