Stainless steel is an alloy of steel, chromium, nickel and other elements such as molybdenum, titanium, copper, manganese and carbon. Of these, the chromium content is generally above 10.5 percent to ensure the production of stainless properties. The structure and properties of stainless steel vary with different elemental compositions. They can be classified into various types such as austenitic stainless steel, martensitic stainless steel, ferritic stainless steel, duplex stainless steel, etc.
Is Stainless Steel Magnetic?
Not all types of stainless steel are magnetic; there are magnetic and non-magnetic stainless steels, depending on the composition. To be magnetic, it must fulfill certain requirements. Stainless steel is available in more than 100 standard alloys, each type with a different composition. Based on their metallurgical properties and microstructure, stainless steels are classified into five categories: austenitic stainless steels, ferritic stainless steels, martensitic stainless steels, duplex stainless steels, and precipitation-hardening steels.
Which Types of Stainless Steel are Magnetic?
Austenitic stainless steel: non-magnetic
generally speaking, austenitic stainless steel is not magnetic. This is because the iron element in the austenitic stainless steel is mostly ferrous ions, in a relatively stable crystal structure, so the magnetism is weak. Although some alloys (e.g. grades 304 and 316) contain iron, these materials are non-ferromagnetic and the crystal structure is important for the magnetic properties. Using heat treatment or work hardening (e.g. bending, drilling, etc.), austenitic stainless steels can become partially magnetic, forming ferrites in certain regions. As a result, austenitic grades exhibit slight magnetism at the edges of mechanical operations (e.g. plates).
Martensitic Stainless Steel: magnetic
martensitic stainless steel is magnetic. This stainless steel in the process, part of the iron element will be ferromagnetic crystal structure form, so has a certain magnetic.
Ferritic Stainless Steel: magnetic
ferritic stainless steel magnetic performance between austenitic stainless steel and martensitic stainless steel. Its magnetic strength depends on the specific composition and process conditions.
Duplex Stainless Steel: magnetic
Duplex stainless steel combines austenitic and ferritic crystals, so it offers the best of both worlds, with magnetic properties and generally higher corrosion resistance than austenitic 304 and 316 stainless steels.
Precipitation Hardening Stainless Steel: non-magnetic
This type of steel, like Grade 17-4 PH, can be non-magnetic in its softened state but may become slightly magnetic after undergoing an aging process known as precipitation hardening. This process strengthens the steel by forming tiny, dispersed particles within the steel matrix.
Non-magnetic Stainless Steel Grades
Magnetic Stainless Steel Grades
- 409
- 430
- 439
- 441
- 434
- 436
- 444
- 446
- 403
- 410
- 410S
- 414/L
- 418
- 420
- 440
- 416
- 2205
- S31803
- S32101
- S32202
- S32304
- S32520
- S32750
- S32760
- S32900
Factors Influencing Magnetism
Several factors influence the magnetic properties of stainless steel:
1. Composition:
The ratio of iron, chromium, nickel, and other elements determines the magnetic or non-magnetic nature of the alloy.
2. Cold Working:
Cold working processes, such as rolling or bending, can induce magnetism in stainless steel.
3. Heat Treatment:
Certain heat treatments can alter the crystal structure of stainless steel, affecting its magnetic behavior.
FAQ
Not all stainless steels are magnetic, 400 series stainless steels and duplex steels are magnetic, and 300 series stainless steels are non-magnetic in the annealed condition.
The magnet will not stick to Austenitic stainless steel under heat treatment condition, Ferritic, Martensitic, and duplex stainless steel are magnetic.