The answer is YES and NO.
Stainless steel magnetic properties vary depending on the grade. There are magnetic and non-magnetic stainless steel.
Let me explain:
Basics About Stainless Steel
Stainless steel is an alloy. Some of the alloying elements include:
- Iron
- Chromium
- Nickel
- Silicone
- Aluminum
- Carbon
- Molybdenum, etc.
As you can see, the alloying elements consist of magnetic and non-magnetic materials.
The most common types of stainless steel are:
- Austenitic stainless steel
- Ferritic stainless steel
- Martensitic stainless steel
- Duplex stainless steel
Under each type of stainless steel, there are grades. As earlier mentioned, you will find that each stainless steel grade has unique magnetic properties.
Stainless Steel Magnetic Properties
Two factors contribute to SS magnetic properties:
- Ferromagnetic materials are part of stainless steel alloys such as iron and nickel.
- The stainless steel crystal structure will determine whether the alloy is magnetic or not
Let’s compare magnetism in stainless steel:
| Type of Stainless Steel | Magnetic Properties of Stainless Steel |
| Austenitic stainless steel | · Most austenitic stainless grades are non-magnetic
· The non-magnetic property is attributed to the austenitic crystal structure. · It can only be magnetized when there is an electric current. However, it rarely forms a permanent magnet · At times, work-hardening or heat treatment may contribute to partial magnetic properties in austenitic stainless steel |
| Ferritic stainless steel | · Magnetic stainless steel since it has a higher iron composition (It has large quantities of ferrite)
· Although the crystal structure of iron and ferrite contribute to the magnetic properties, there are certain grades with weak magnetic properties · Examples of magnetic stainless steels here include 409, 430, 439, etc. |
| Martensitic stainless steel | · They are magnetic
· Common types of magnetic stainless steel in this category include 410, 420, 440, etc. · They have iron, and crystal structures that contribute to the magnetic property |
| Duplex stainless steel | · It has both Ferritic and austenitic SS properties. They are magnetic. |
| Precipitation hardening stainless steel | · Most of these steels become magnetic after hardening |
From the table above, it is quite evident that:
- Both ferrite and iron contribute to the stainless steel magnetism
- On the other hand, austenite offsets the ferrites thereby making such stainless steel non-magnetic metals.
Why Understand Stainless Steel Magnetic Properties
Understanding stainless steel magnetism will help you decide whether the grade is suitable for a specific application or not.
In certain processes, the magnetic properties of stainless can be advantageous. Whereas in some applications, magnetism can cause problems.
FAQs
Can Magnets Stick on Stainless Steel?
It will depend on the type of stainless steel. Austenitic stainless steels are non-magnetic metals. Therefore, the magnet will not stick on an austenitic stainless steel surface.
Is there a Correlation between Magnetism and Corrosion Resistance in Stainless Steel?
No, the two are not related in any way.
Take for example;
- 316 stainless steel has one of the best corrosion resistance properties, however, they are not magnetic.
- At the same time, the 420 and 430 stainless steel grades have the best corrosion resistance properties and are highly magnetic at the same time.
Is Stainless Steel 304 Magnetic?
SS 304 is an austenite making it non-ferromagnetic material.
Is Stainless Steel 316 Magnetic?
316 is a non-magnetic stainless steel. At times, they behave like paramagnetic materials.
Is Austenitic Stainless Steel Magnetic?
No.
The non-magnetic property is attributed to the crystal structure.
Is Stainless Steel Magnetic or Not?
Yes and no.
Magnetism in stainless steel depend on the grade. For instance, austenitic stainless steel is nonmagnetic. At the same time, ferritic and martensitic SS are magnetic.
Is Food Grade Stainless Steel Magnetic?
Yes and no.
Food grade stainless steel have chromium content less than 16%.
Among the most common food-grade stainless steels are 304 and 316. They are non-magnetic.
Another popular option is the 430 grade which is popular for kitchen equipment. It is a magnetic SS.
Conclusion
In short, stainless steel can be magnetic or non-magnetic depending on the grade. However, for stainless steel to be magnetic, it must meet two critical criteria. First, iron must be present, while the crystal structure should be martensitic or ferrite. Of course, austenite must be low.
More Resources:
Magnetism in Stainless Steel – Source: Metal Supermarket
Is Steel Magnetic – Source: HM
SS Magnetism – Source: UMD
Steel Melting Point – Source: HM