Stainless steel is magnetized or not: how to identify stainless steel

Given that fact, that stainless steel is now available in a wide variety of brands, it is impossible to answer the question unequivocally, whether it is magnetized or not. The magnetic properties of stainless steels depend on the chemical composition and, in accordance, from the internal structure of alloys.

Portable metal analyzer allows you to quickly determine the content of chemical elements and draw conclusions about the quality of stainless steel

What determines the magnetic properties of materials

Magnetic field with a certain level of intensity (N) acts on the bodies placed in it in this way, which magnetizes them. The intensity of such magnetization, which is denoted by the letter J, directly proportional to the field strength. In the formula, which calculates the intensity of magnetization of a substance (J =? H), the coefficient of proportionality is also taken into account? - magnetic susceptibility of the substance.

Depending on the value of this factor, all materials can fall into one of three categories:

• paramagnetics - coefficient? more than zero;
• Diamagnet -? is zero;
• ferromagnets - substances, whose magnetic susceptibility is significant (such substances, to which, in particular, include iron, cobalt, nickel and cadmium, able to actively magnetize, even when placed in weak magnetic fields).

Directions of action of magnetic moments of neighboring atoms in substances of different magnetic nature

Magnetic properties, which has stainless steel, also related to its internal structure, which may include austenite, ferrite and martensite, as well as their combinations. The magnetic properties of stainless steel are affected as the phase components themselves, so and so, in what proportion they are in the internal structure.

Stainless steels with good magnetic properties

Stainless steel has good magnetic properties, in which such phase components prevail:

• Martensite - is a ferromagnet in its pure form.
• Ferrite - this phase component of the internal structure of stainless steel, depending on the heating temperature can take two forms. Such a structural form becomes a ferromagnet in that case, if the steel is heated to temperature, below the Curie point. If the heating temperature of stainless steel is above this point, then the alloy begins to be dominated by high-temperature delta-ferrite, which is a pronounced paramagnetic.

From all the above we can conclude that, magnetized and stainless steel, in the internal structure of which martensite predominates. As well as usual carbon steels, such alloys react to the magnet. On this basis, they can be distinguished from non-magnetic.

The ability of stainless steel to be magnetized does not affect its corrosion resistance

Stainless steel, in which ferrite or its mixture with martensite predominates, most often also belong to the ferromagnet, but their properties may differ depending on the ratio of the phase components of their internal structure.

Stainless steel, whose magnetic properties may change, Are mainly chromium and chromium-nickel alloys, which may belong to one of the following groups.

martensitic

Steels with martensitic internal structure, which, as well as usual carbon, can be strengthened by hardening and tempering. Taka stainless steel, except for general mechanical engineering enterprises, actively used in everyday life (in particular, it is used to make cutlery and cutting tools). Among the most common brands of such magnetic steels, products from which are made with heat treatment and can be subjected to finishing grinding and polishing, include 20X13, 30Х13, 40Х13.

Steel grade 30X13 is less ductile, than alloy 20X13, despite the similar composition (click to enlarge)

This category also includes an alloy brand 20X17H2, which has a high content of chromium in its chemical composition, which significantly enhances its corrosion resistance. Why such stainless steel is popular? The point is, what, in addition to high corrosion resistance, it is characterized by excellent machinability by cold and hot stamping, cutting methods. in addition, products from such material are well welded.

ferrite

Common magnetic steel ferrite type, which due to the low carbon content in its chemical composition is more soft, than martensitic alloys, is 08Х13, actively used in food production. Products and equipment are made of such stainless steel, designed for washing, sorting, grinding, sorting, as well as transportation of food raw materials.