Is Stainless Steel a non ferrous metal?

In summary, a major recycler's website explains that they separate ferrous materials from nonferrous and further separate various metals from the stream of nonferrous metals. Stainless steel, which contains a significant amount of chromium, is typically considered non-ferrous due to its non-magnetic properties. However, it may still contain small amounts of ferrite or martensite, which can increase its magnetic permeability. In practical terms, austenitic stainless steels are used for "non-magnetic" applications, but a maximum magnetic permeability may need to be agreed upon between customers and suppliers.
  • #1
rollingstein
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Read this quote on a major recycler's website:

"During this processing, we separate ferrous materials from nonferrous and further separate the copper, aluminum, brass, stainless steel, and other metals from the stream of nonferrous metals. "


Is Stainless considered non-ferrous? Why? Isn't it mostly iron?

Or am I misreading what they mean here.

http://www.omnisource.com/buy/?p=our_products
 
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  • #2
hi rollingstein! :smile:

from the british stainless steel association (http://www.bssa.org.uk/faq.php?id=24) …

(motto: "making the most of stainless steel" … wow! who'd have guessed that? :rolleyes:)

Is stainless steel non-magnetic?

It is commonly stated that “stainless steel is non-magnetic”. This is not strictly true and the real situation is rather more complicated. The degree of magnetic response or magnetic permeability is derived from the microstructure of the steel. A totally non-magnetic material has a relative magnetic permeability of 1. Austenitic structures are totally non-magnetic and so a 100% austenitic stainless steel would have a permeability of 1. In practice this is not achieved. There is always a small amount of ferrite and/or martensite in the steel and so permeability values are always above 1. Typical values for standard austenitic stainless steels can be in the order of 1.05 – 1.1. See Composition effects on the magnetic permeability of austenitic stainless steels

It is possible for the magnetic permeability of austenitic steels to be changed during processing. For example, cold work and welding are liable to increase the amount of martensite and ferrite respectively in the steel. A familiar example is in a stainless steel sink where the flat drainer has little magnetic response whereas the pressed bowl has a higher response due to the formation of martensite particularly in the corners.

In practical terms, austenitic stainless steels are used for “non-magnetic” applications, for example magnetic resonance imaging (MRI). In these cases, it is often necessary to agree a maximum magnetic permeability between customer and supplier. It can be as low as 1.004.​
(se also http://en.wikipedia.org/wiki/Stainless_steel#Properties)
 
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  • #3
Stainless steels contain a large percentage of alloying elements, chiefly chromium, which makes it prudent to separate this material from mild steel for recycling.
 
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  • #4
Strictly speaking, any alloy that includes iron is a ferrous material. For handling purposes, alloys that are non-magnetic are often considered non-ferrous.
 
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  • #5
Gotcha! Thanks everyone!
 

1. Is stainless steel considered a non ferrous metal?

Yes, stainless steel is considered a non ferrous metal. Non ferrous metals are those that do not contain iron as a major component. Stainless steel is primarily made up of iron, but it also contains a significant amount of chromium, which gives it its anti-corrosive properties. Therefore, it is classified as a non ferrous metal.

2. What are the main characteristics of stainless steel?

Stainless steel is known for its high strength, durability, and resistance to corrosion. It is also non-magnetic and has a shiny, silver appearance. These properties make it a popular choice for a wide range of applications, from kitchen utensils to medical equipment.

3. Can stainless steel rust or corrode?

Although stainless steel is highly resistant to corrosion, it is not completely immune. Certain environmental conditions, such as exposure to saltwater or harsh chemicals, can cause stainless steel to rust or corrode. However, compared to other metals, stainless steel has a much higher resistance and is often the preferred choice for applications where corrosion is a concern.

4. Is stainless steel more expensive than ferrous metals?

In general, stainless steel tends to be more expensive than ferrous metals such as iron or steel. This is because stainless steel contains additional elements, such as chromium and nickel, which increase its strength and resistance to corrosion. However, the cost of stainless steel can vary depending on the specific grade and application.

5. Are there different types of stainless steel?

Yes, there are several different types of stainless steel, each with its own unique properties and applications. The most common types include austenitic, ferritic, martensitic, and duplex stainless steel. Each type has a different chemical composition and microstructure, giving it specific characteristics and uses in various industries.

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