Iron vs. Stainless Steel: Understanding the Differences

[aek]

Hi all,

i'm trying to figure out the difference between iron and stainless steel. Other than maybe the appearance, that's all i can say. I can't find any links or any relevant chapters in my textbook. In the back of my mind i think the main difference is the bonding but I'm not sure. Can someone be able to help me.

Thanks

AEK

 

[brewnog]

Iron is an element, stainless steel is an alloy. The addition of other elements (particularly chromium when talking about stainless, but also molybdenum, manganese, phosphorus, nickel and copper, plus some others) has an alloying effect. Carbon, whilst not a metal, is universally found in steels.

All these alloying elements add particular properties to the iron. The inclusion of chromium (between 10 and 15% I recall, but check me) adds corrosion resistance and enhances the aesthetic quality of the steel. Carbon is added for mechanical reasons, and improves the material's strength and toughness.

Stainless steels are often used in applications where hygeine, corrosion resistance, appearance, impact resistance, strength/weight ratio or ease of fabrication are desired.

Any more specific questions hit me!

 

[aek]

absolutely, but how about the bonding present in both solids?

 

[Borek]

Chromium is passivated by its oxygens and that creates resistance of the stainless steel.

Steel is an alloy containing carbon. Iron carbide (Fe3C) called cementite is responsible for steel strength.

I doubt there is a specific bonding present in the iron-chromium alloys.

Just small addition to the brewnog answer.

 

[wachiraporn]

Dear All,

I really doubt whether the stainless steel 430 same as stainless iron 430. Please help to explain what they are and which one is good without rust. I am really blank pleasesseee help.

Thanks,
wachiraporn

 

[Borek]

If it is stainless, it shouldn't rust. If it is stainless, it can't be iron.

Argh, I just found a mistake in my oooooold post:

Chromium is passivated by its oxygens

I meant oxides.

 

[wachiraporn]

Neither nor you heard the stainless iron, but chinese factories claim that they use this one for the home appliances production such as in the convection oven, use shield for covering the motor fan. I thought it might have the metal mix between iron and stainless because they call stainless iron...Still doubt of it!

 

[Astronuc]

Dear All,

I really doubt whether the stainless steel 430 same as stainless iron 430. Please help to explain what they are and which one is good without rust. I am really blank pleasesseee help.

Thanks,
wachiraporn

If one is using the AISI designation 430, then saying stainless iron makes no sense, because 430 has a specific composition. AISI 430 or stainless steel 430 is a ferritic steel with 0.08 % carbon by weight, about 1% max Mn, 1% max Si, and 16 to 18 % Cr.

 

[Astronuc]

Neither nor you heard the stainless iron, but chinese factories claim that they use this one for the home appliances production such as in the convection oven, use shield for covering the motor fan. I thought it might have the metal mix between iron and stainless because they call stainless iron...Still doubt of it!

Perhaps they use iron because some define steel as an iron alloy having at least 0.2% C, but then the 16 to 18% of Cr and other elements would qualify 430 as an alloy steel.