difference between cast steel and cast Iron

[garlin]

How does the layman tell the difference between cast steel and cast iron if the steel is poured into a casting to make, lets say a Wok?
Case in point, I received a cast Wok from my Son and Daughter that are on tour in Japan. The Wok appears to have been poured. The top or what I call the circumference edge, top edge, you can see difference in the material by 1/16 to 1/32 of an inch. The handles are cast in with the bowl of the Wok. The finish outstanding. The finest I have seem and there is some type of coating that food will not stick to. It has the weigh of cast iron. I say that from the experience I have from
handling iron cookware. It is hard for me to think this Wok is cast iron because of the extra nice finish it has.

Howard g.Cutler

[Steve_Stephens]

I would think the only difference between cast iron and cast steel would be the material with steel being an alloy of iron and another metal.  I don't see what advantage there would be to using steel on cookware.  We have a local foundry that pours cast steel in making castings for heavy duty truck spring hangers and other items.  The casting process would be the same I think.  Chicago Hardware Foundry cast some non-magnetic pieces of cookware probably in the 1930's.  It is a much lighter silver color than cast iron but I don't know if it is cast stainless steel or what-just that a magnet will not stick and it, other than the color, looks just like cast iron.  Lodge now has some kind of coating for their cookware that they claim is non-stick.

Steve

[C. B. Williams]

This is not my expertise but: I thought both cast iron and steel could be alloys. I have always understood that Griswold (and others) used an alloy that had a minimum contraction factor with some nickel allowing them to make thin castings without cracking when cooling. I thought steel was made using air to blast out some carbon and with other metals making an alloy that is harder than iron. Both being alloys. The Bessemer process of making steel? CB

[Steve_Stephens]

Steel is "      A generally hard, strong, durable, malleable alloy of iron and carbon, usually containing between 0.2 and 1.5 percent carbon, often with other constituents such as manganese, chromium, nickel, molybdenum, copper, tungsten, cobalt, or silicon, depending on the desired alloy properties, and widely used as a structural material."

Iron is "A silvery-white, lustrous, malleable, ductile, magnetic or magnetizable, metallic element occurring abundantly in combined forms, notably in hematite, limonite, magnetite, and taconite, and used alloyed in a wide range of important structural materials."

Stainless steel is "Any of various steels alloyed with at least 10 percent chromium and sometimes containing other elements and that are resistant to corrosion or rusting associated with exposure to water and moist air."

An alloy is "A homogeneous mixture or solid solution of two or more metals."

I see where the dictionary definition of steel and alloy do not correspond.  It says "(steel is) an alloy of iron and carbon" yet carbon is not a metal so how can it make an alloy?

Iron is an element, i.e. composed on only one thing, iron.  It can't be broken down into other substances.  As used, however, in iron cookware it does contain some degree of carbon but since carbon is not a metal that doesn't make iron an alloy.  If iron used in cast iron cookware had any other metal added it would cease to be iron but would probably become steel.  I do think that Griswold used pure grey iron for their castings.  Today, who knows what is used.  We'll have to ask Lodge and, hopefully get a talk from the metalmasters there.

Steel is iron plus certain other metals added.  Steel can be broken down into iron plus whatever other metal(s) it was alloyed with.

Mr. Greg, chemist, can you tell us if my post is on the mark or is missing something?

Thanks,
Steve

[C. B. Williams]

All cast irons are not pure iron





High-alloy cast irons are an important group of materials whose production should be considered separately from that of the ordinary types of cast irons. In these cast iron alloys, alloy content is well above 4% and, consequently, they cannot be produced by ladle additions to irons of otherwise standard compositions. The producing foundries usually have the equipment needed to handle the heat treatment and other thermal processing unique to the production of these alloys.
The heat treatment practices for the following high-alloy graphitic irons are described:
Austenitic gray and ductile irons
High-silicon irons for heat resisting applications
High-silicon irons for corrosion resisting applications


High-alloy cast irons are an important group of materials whose production should be considered separately from that of the ordinary types of cast irons. In these cast iron alloys, alloy content is well above 4% and, consequently, they cannot be produced by ladle additions to irons of otherwise standard compositions. The producing foundries usually have the equipment needed to handle the heat treatment and other thermal processing unique to the production of these alloys.

The cast iron alloys discussed in this article are alloyed for increased abrasion resistance, for strength and oxidation resistance at elevated temperatures, and for improved corrosion resistance. They include the high-alloy graphitic irons and the high-alloy white irons.

The heat treatment practices for the following high-alloy graphitic irons are described:

Austenitic gray and ductile irons
High-silicon irons for heat resisting applications
High-silicon irons for corrosion resisting applications
The high-alloy graphitic cast irons have found special use primarily in applications requiring (1) corrosion resistance or (2) strength and oxidation resistance in high-temperature service. Those alloys used in applications requiring corrosion resistance comprise the nickel-alloyed (13 to 36% Ni) gray and ductile irons, and the high-silicon (14.5% Si) gray irons.
The alloyed irons produced for high-temperature service comprise the austenitic, nickel-alloyed gray and nodular irons, the high-silicon (4 to 6% Si) gray and nodular irons and the aluminum-alloyed gray and nodular irons. Two groups of aluminum-alloyed irons are recognized: the 1 to 7% Al irons and the 18 to 25% Al irons.


Austenitic Nickel-Alloyed Graphitic Irons
These nickel-alloyed austenitic irons have found usefulness in applications requiring corrosion resistance, wear resistance, and high-temperature stability and strength. Additional properties of benefit are low thermal expansion coefficients, nonmagnetic properties, and cast iron materials having good toughness at low temperatures. The procedures and temperatures of the heat treatments for these ductile irons with nodular graphite are similar to those for gray (flake-graphite), corrosion-resistant austenitic cast irons.

[C. B. Williams]

Cast iron is a generic term that identifies a large family of ferrous alloys. Cast irons are primarily alloys of iron that contain more than 2% carbon and 1% or more silicon. Low raw material costs and relative ease of manufacture make cast irons the least expensive of the engineering metals. Cast irons may often be used in place of steel at considerable cost savings. The design and production advantages of cast iron include:

Low tooling and production cost

Ready availability

Good machinability without burring

Readily cast into complex shapes

Excellent wear resistance and high hardness (particularly white irons)

High inherent damping

[Steve_Stephens]

Griswold and other companies probably fine tuned the iron they used as improvements were discovered.  Some Griswold catalogs say "Made of the highest grade cast iron--with exclusive Griswold improvements."

I thought I read in some Griswold literature that they used "pure grey iron".  I don't know if this would be an alloy or pure iron with the proper amount of carbon.   It would be nice to know what changes were made over the years and if those changes might be responsible for some differences we see in Griswold's iron and between Griswold and other maker's iron.

This is a subject that I don't know a lot about especially of all those advanced iron casting alloys C.B. showed.

Steve

[C. B. Williams]

The only thing I was trying to show is that 'cast iron' is not just casting iron (the element), but adding certain things to improve the quality (characteristic) for the purpose it is intented to be used as. I had a friend who once worked in a foundry, and when he saw my Griswold for the first time said "they had to use something special in the iron because I know you can't cast iron that thin and it not crack".  I for sure don't know, I am in construction and a woodworker. I do know that this friend was a master machinist for the last 25 +- years of his life and I will bet knew what he was talking about. C B

[garlin]

HI!


John Myers
I suggest the smoothness of cast iron ends of the old seed box  may have been caused by the environment in which the seed box operated. The movement the seed over the casting and even the dust and dirt can brings about the results of smooth farm equipment casting and leave the raised cast part number as sharp in detail as freshly stamped quarter. I'm not saying this is the case with your seed box only that it may be. Thank you for your response to my question.
The Wok being a new piece of cast iron has a fine finish. The Japanese foundry that cast the Wok has come up, in my opinion, with an outstanding finish for cast iron, if it is cast iron.

Steve Stephens
I take you are saying when casting steel or casting cast iron the finish the of two would be just about the same. Being that there is no advantage in the functionality or the finish use of steel and steel being the more costly, why use it.
The only thing I know that the Wok is an nice piece to cook with. Thank you for your input to my question.

C. B. Williams

When you use the term ,"minimum contraction factor", do you mean the finished cast iron is more readily for expansion, when heated and/or more readily for contraction when cooled?  In other words the ,"minimum contraction factor",  prevents cracking during the heating and cooling of the cast piece. Or have I miss the whole point of it?

The rest of the conversation was interesting but I have not the expertise to discuss it with any real input.
Thank you all.

[Steve_Stephens]

Steve Stephens
I take you are saying when casting steel or casting cast iron the finish the of two would be just about the same.

Howard,
Not necessarily WOULD the casting finish be the same but I think it COULD be.  Depends on what casting sand is used and the size of the piece being cast as larger pieces often required coarser casting sand so the gases could escape from the casting.  Larger castings release more gas.  I don't know if cast STEEL would even be more desirable for cookware than cast IRON.  

Steve