Is stainless steel magnetic?

Is stainless steel magnetic: magnetic properties of stainless steel

Considering the fact that stainless steel today is produced in a wide variety of brands, it is impossible to unequivocally answer the question of whether it is magnetic or not. The magnetic properties of stainless steels depend on the chemical composition and, accordingly, on the internal structure of the alloys.

A portable metal analyzer allows you to quickly determine the content of chemical elements and make a conclusion about the quality of stainless steel

What determine the magnetic properties of materials?

A magnetic field with a certain level of its intensity (H) acts on bodies placed in it in such a way that it magnetizes them. In this case, the intensity of such magnetization, which is designated by the letter J, is directly proportional to the field strength. The formula by which the intensity of magnetization of a certain substance is calculated (J = ϞH) also takes into account the coefficient of proportionality Ϟ - the magnetic susceptibility of the substance.

Depending on the value of this coefficient, all materials can be included in one of three categories:

• paramagnets – coefficient Ϟ is greater than zero,
• diamagnetic materials – Ϟ is equal to zero,
• ferromagnets are substances whose magnetic susceptibility is significant (substances, which, in particular, include iron, cobalt, nickel and cadmium, are capable of actively magnetizing, even when placed in weak magnetic fields).

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

The magnetic properties that stainless steel has are also associated with its internal structure, which can include austenite, ferrite and martensite, as well as combinations thereof. At the same time, the magnetic properties of stainless steel are influenced both by the phase components themselves and by the ratio in which they are found in the internal structure.

Stainless steels with good magnetic properties

Stainless steel, in which the following phase components predominate, has good magnetic properties:

• 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. This structural form becomes ferromagnetic if the steel is heated to a temperature below the Curie point. If the heating temperature of the stainless steel is above this point, then high-temperature delta ferrite, which is a pronounced paramagnet, begins to predominate in the alloy.

From all of the above, we can conclude that the stainless steel that is magnetic is one in which martensite predominates in its internal structure. Like regular carbon steels, these alloys react to magnets. By this feature they can be distinguished from non-magnetic ones.

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

Stainless steels, in which ferrite or its mixture with martensite predominate, are most often also classified as ferromagnetic, but their properties may vary depending on the ratio of the phase components of their internal structure.

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

Steels with a martensitic internal structure, which, like conventional carbon steels, can be strengthened by quenching and tempering. Such stainless steel, in addition to general engineering enterprises, is actively used in everyday life (in particular, cutlery and cutting tools are made from it). The most common grades of such magnetic steels, products from which are produced with heat treatment and can be subjected to finishing grinding and polishing, include 20Х13, 30Х13, 40Х13.

Steel grade 30Х13 is less ductile than alloy 20Х13, despite its similar composition (click to enlarge)

This category also includes the 20Х17Н2 alloy, which is characterized by a high chromium content in its chemical composition, which significantly enhances its corrosion resistance. Why is this stainless steel popular? The fact is that, in addition to high resistance to corrosion, it is characterized by excellent workability using cold and hot stamping and cutting methods. In addition, products made from such material are well welded.

A common ferritic-type magnetic steel, which, due to the low carbon content in its chemical composition, is softer than martensitic alloys, is 08Х13, which is actively used in food production. Such stainless steel is used to make products and equipment intended for washing, sorting, grinding, sorting, and transporting food raw materials.

Mechanical properties of steel 08Х13

A popular brand of magnetic stainless steel, the internal structure of which consists of

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Is stainless steel magnetic: magnetic properties of stainless steel Link to main publication

Source: https://tradesmarter.ru/analitika/prs_magnititsya-li-nerjaveyka-magnitnye-svoystva-nerjaveyushchey-stali_42c4a.html

Magnetic stainless steels and corrosion resistance

Are there magnetic stainless steels and how does this affect corrosion resistance?

There is no clear answer to the question of whether stainless steel is magnetic, since the magnetic properties of alloys are determined by the properties of their structural components.

Classification of materials according to their magnetic properties

Bodies placed in a magnetic field become magnetized. The magnetization intensity (J) is directly proportional to the increase in field strength (H):

J= ϰH, where ϰ is a proportionality coefficient called magnetic susceptibility.

If ϰ>0, then such materials are called paramagnetic, and if ϰ

Some metals - Fe, Co, Ni, Cd - have extremely high positive susceptibility (about 105); they are called ferromagnets. Ferromagnets are intensely magnetized even in weak magnetic fields.

Stainless steels for industrial use may contain ferrite, martensite, austenite, or combinations of these structures in different proportions. It is the phase components and their ratio that determine whether a stainless steel is magnetic or not.

Magnetic stainless steel: structural composition and grades

There are two phase components of steel with strong magnetic characteristics:

• Martensite, from the point of view of magnetic properties, is a pure ferromagnet.
• Ferrite can have two modifications. At temperatures below the Curie point, it, like martensite, is ferromagnetic. High temperature delta ferrite is paramagnetic.

Thus, corrosion-resistant steels, the structure of which consists of martensite, are magnetic stainless steel. These alloys react to magnets like regular carbon steel. Ferritic or ferritic-martensitic steels can have different properties depending on the ratio of phase components, but, most often, they are ferromagnetic.

This category includes chromium and some chromium-nickel steels. They are divided into the following subgroups:

• Martensitic steels are hard and can be strengthened by quenching and tempering, just like regular carbon steels. They are used mainly for the production of cutlery, cutting tools and general mechanical engineering.

Steels 20Х13, 30Х13, 40Х13 martensitic class are produced mainly in a heat-treated ground or polished state

Chromium-nickel martensitic steel 20Х17Н2 has higher corrosion resistance than 13% chromium steels. This steel is highly manufacturable - it lends itself well to stamping, hot and cold, can be processed by cutting, and can be welded by all types of welding.

• Ferritic steels of type 08Х13 are softer than martensitic steels due to their lower carbon content. One of the most consumed ferritic steels is the magnetic corrosion-resistant alloy AISI 430, which is an improved analogue of grade 08Х17. This steel is used for the manufacture of technological equipment for food production, used for washing and sorting food raw materials, grinding, separating, sorting, packaging, and transporting products.
• Ferritic-martensitic steels (12X13) have martensite and structurally free ferrite in their structure.

Non-magnetic stainless steel

Non-magnetic alloys include chromium-nickel and chromium-manganese-nickel steels of the following groups:

• Austenitic steels occupy a leading position in terms of production volume. Non-magnetic stainless steel of the austenitic class is widely used - AISI 304 steel (analogue - 08Х18Н10). This material is used in the production of equipment for the food industry, the manufacture of containers for kvass and beer, evaporators, cutlery - pots, pans, bowls, kitchen sinks, in medicine - for needles, marine and refrigeration equipment, plumbing equipment, tanks for various liquids composition and purpose and dry substances. Steels 08Х18Н10, 08Х18Н10Т, 12Х18Н10Т (used in hardware A2), 10Х17Н13М2Т (used in hardware for use in aggressive environments, acid-resistant and salty, A4) have excellent manufacturability and high corrosion resistance even in chemical production vapors and ocean waters.
• Austenitic-ferritic steels are characterized by a high chromium content and a low nickel content. Additional alloying elements are molybdenum, copper, titanium or niobium. These steels (08Х22Н6Т, 12Х21Н5Т, 08Х21Н6М2Т) have some advantages over austenitic steels - higher strength while maintaining the required ductility, greater resistance to intergranular corrosion and corrosion cracking.

The group of non-magnetic materials also includes corrosion-resistant austenitic-martensitic and austenitic-carbide steels.

Method for determining whether non-magnetic steel is corrosion resistant

As the information presented above shows, there is no clear answer to the question – is stainless steel magnetic or not?

If steel is magnetic, can you tell if it is corrosion resistant? To answer this question, you need to clean a small area of ​​the part (wire, pipe, plate) until it shines. Two or three drops of a concentrated solution of copper sulfate are applied and rubbed onto the cleaned surface. If the steel is coated with a layer of red copper, the alloy is not corrosion resistant. If no changes have occurred on the surface of the material, then this is stainless steel.

It is impossible to check at home whether steel belongs to the group of food alloys.

The magnetic properties of stainless steel do not in any way affect the performance characteristics, in particular, the corrosion resistance of the material.

Having received the necessary information, you can select the hardware and stainless steel fasteners you need in our store: http://lednik.com.ua/shop

Source: https://lednik.com.ua/articles/492/

Is stainless steel magnetic?

Among the main properties of a metal, the degree of magnetism is distinguished. Recently, there is simply a huge number of stainless steels, the performance characteristics of which can differ significantly. In many ways, the property under consideration depends on the chemical composition of the alloy. It is quite difficult to independently check the degree of magnetism, since it can vary depending on operating conditions.

Is stainless steel magnetic?

Non-magnetic stainless steels

There are quite a large number of metals that do not have magnetic properties. They contain nickel and manganese. The following groups of alloys are distinguished:

1. Austenites are the most widely used. This group includes 08Х18Н10 and 10Х17Н13М2Т. These metals are actively used in the manufacture of various products in the food industry, for example, cutlery and dishes. Increased corrosion properties are maintained in almost any operating environment.
2. Austenitic-ferritic stainless steels 08Х22Н6Т and 08Х21Н6М2Т are characterized by an increased concentration of chromium and some other alloying elements. To change the basic characteristics, other chemical elements are also included in the composition.

Steel 10Х17Н13М2ТSteel 08Х18Н10

Non-magnetic stainless steel is selected when the resulting product should not respond to the influence of a magnetic field.

The choice of stainless steel can be made not only taking into account the degree of magnetism, but also the following points:

1. Weldability. Some versions need to be preheated, others weld well even when cold.
2. Ductility is taken into account when choosing a material for cold and hot stamping. A sufficiently high ductility index determines that it is possible to stamp metal sheets in a cold state.
3. Corrosion resistance when exposed to high temperatures. Many metals lose their characteristics when exposed to strong heat, including corrosion resistance.
4. Price is also an important factor. Metals can have high performance characteristics, but due to their high cost, their use for the production of some products is impractical.
5. Degree of machinability. Often, workpieces are supplied for cutting on special equipment. Due to the high concentration of carbon, hardness increases and the surface treatment process becomes more complicated.
6. Heat resistance is also an important quality that is considered when choosing a material. With good heat resistance, the manufactured product does not lose its strength and hardness when exposed to high temperatures.

Some brands are subjected to heat treatment, which increases the strength and hardness of the surface.

When tempering is carried out, the structure becomes more plastic and resistant to variable loads.

How to determine whether magnetic or non-magnetic steel is stainless?

As previously noted, it is possible to determine whether stainless steel is magnetic without the use of special equipment. Among the features of the procedure, we note the following points:

1. The test area should be polished to a high shine. Hand tools and special materials can be used for this.
2. A few drops of concentrated copper sulfate are applied to the cleaned area.
3. If the metal is stainless steel, then a red coating will appear on the surface.

Determination of magnetic properties using vitriol

This process allows you to determine which stainless steel is magnetic and which is not corrosion resistant. It is almost impossible to determine the characteristics of a food alloy on your own.

Magnetic properties can also be checked using a regular magnet. However, it does not give an accurate result.

That is why it is recommended to purchase products from reputable manufacturers.

Portable metal analyzer

In conclusion, we note that magnetic properties do not in any way reduce the corrosion resistance of the surface. That is why such alloys are characterized by a wide range of applications.

Source: https://stankiexpert.ru/spravochnik/materialovedenie/magnititsya-li-nerzhaveika.html

Magnetic or not

We make most of our products from stainless steel. The second bottom of the chimney must be made of stainless steel - this part absorbs hot smoke from the chimney, so the requirements for anti-corrosion protection are increased here.

Sometimes our clients try to check the quality of stainless steel using a magnet - there is a “folk way”. But do not rush to accuse the supplier of deception if you suddenly discover the magnetic properties of “stainless steel”. In fact, more than 250 grades of steel are now produced, which have the general name “stainless”, but are very different in composition and properties and may well be magnetic.

Modern classification of stainless steel

Stainless steel is a type of alloy steel that is resistant to corrosion due to its chromium content. In the presence of oxygen, chromium oxide is formed, which creates an inert film on the surface of the steel, protecting the entire product from adverse influences.

Not every grade of stainless steel demonstrates the resistance of chromium oxide film to mechanical and chemical damage. Although the film recovers when exposed to oxygen, special grades of stainless steel have been developed for use in aggressive environments.

The first conditional type of division into groups:

• Food
• Heat resistant steel
• Acid resistant steel

The second type of classification is by microstructure:

• Austenitic - non-magnetic steel with the main components of 15-20% chromium and 5-15% nickel which increases corrosion resistance. It is well suited to heat treatment and welding. It is the austenitic group of steels that is most widely used in industry and in the production of fasteners.
• Martensitic steels are significantly harder than austenitic steels and can be magnetic. They are hardened by quenching and tempering like simple carbon steels, and are used mainly in the manufacture of cutlery, cutting tools and general engineering. More susceptible to corrosion.
• Ferritic steels are much softer than martensitic steels due to their low carbon content. They also have magnetic properties.

Stainless steel markings

In Russia and the CIS countries, an alphanumeric system has been adopted, according to which numbers indicate the content of steel elements, and letters indicate the name of the elements. The designations common to all are the letter designations of alloying elements: H - nickel, X - chromium, K - cobalt, M - molybdenum, B - tungsten, T - titanium, D - copper, G - manganese, C - silicon.

Standard stainless steel, according to GOST 5632-72, is marked with letters and numbers (for example, 08Х18Н10Т). In the United States, there are several systems for naming metals and their alloys. This is due to the presence of several standardization organizations, these include AMS, ASME, ASTM, AWS, SAE, ACJ, ANSI, AJS. It is quite clear that such marking requires additional clarification and knowledge when trading metal, placing orders, etc.

Europe (EN)	Germany (DIN)	USA (AISI)	Japan (JIS)	CIS (GOST)
1.4021	X20Cr13	(420)	SUS 420 J1	20Х13
1.4028	X30Cr13	(420)	SUS 420 J2	30Х13
1.4031	X39Cr13	SUS 420 J2	40Х13
1.4016	X6Cr17	430	SUS 430	12Х17
1.4510	X3CrTi17	439	SUS 430 LX	08Х17Т
1.4301	X5CrNI18-10	304	SUS 304	08Х18Н10
1.4541	X6CrNiTi18-10	321	SUS 321	08Х18Н10Т
1.4401	X5CrNiMo17-12-2	316	SUS 316	08Х17Н13М2
1.4404	X2CrNiMo17-12-2	316 L	SUS 316 L	03Х17Н14М2
1.4571	X6CrNiMoTi17-12-2	316 Ti	SUS 316 Ti	10Х17Н13М2Т
1.4435	X2CrNiMo18-14-3	316 L	SUS 316 L	03Х17Н14М2
1.4878	X12CrNiTi18-9	321H	12Х18Н10Т
1.4845	X12CrNi25-21	310 S	20Х23Н18

Of the variety of brands, we use three main ones in our production - AISI 304, AISI 316 and AISI 430.

Read more about the stainless steel grades we use

•  Stainless steel AISI 430 (Russian standard 12X17); 

Due to the low carbon content, it is the most flexible and bends relatively easily. A high percentage of chromium provides a high level of protection.

Retains its properties in corrosive and sulfur-containing environments, and is resistant to sudden temperature changes.

We use AISI 430 stainless steel for bending strips, decorative items, intake hoods, chimneys (if there is no gas or diesel), and external insulation of chimneys on sandwich pipes.

• Stainless steel AISI 304 (Russian standard 08Х18Н10);

This is the most popular stainless steel, which is in great demand in all industries, including our bending production. Has a high level of corrosion resistance.

Our main use for this type of stainless steel is chimneys, diesel and gas penetrations, internal pipes on sandwich pipes for chimneys and other products that will be used in aggressive environments.

AISI 304 stainless steel is chromium-nickel and belongs to the austenitic group of steels, that is, it is not magnetic. Just like its analogues steel 08Х18Н10, 08Х18Н10Т, 12Х18Н10Т, etc.

However, under certain physical influences, rolled metal from this group can exhibit magnetic properties. For example, when welding any type, under the influence of high temperature, alloying elements burn out and the structure of the metal changes at the weld site.

Accordingly, at this point the metal begins to exhibit magnetic properties. A change in the structure of the crystal lattice of a metal also occurs under mechanical influence, such as forging metal, rolling threads, pressing, bending metal, etc. Which also leads to the manifestation of magnetic properties.

At the same time, the general chemical and physical properties of steel do not change.

Source: https://eurogib.ru/news/read/articles/magnititsya_ili_net_nerzhaveyka_/

AISI 430 is magnetic or not

How to distinguish high-quality stainless steel fittings or strip from a cheap and short-lived copy? People often ask the question: “is aisi 430 magnetic or not?” No one can give an exact answer. The reason is that to obtain blanks you need more than 5 elements that have different parameters. In combination with each other, the product completely changes its attitude towards magnets.

Metal products are goods based on an alloy of ferrous or non-ferrous metals. Depending on the combination of components and their proportion to the total mass, not only malleability and resistance to physical damage, but also external characteristics change. Often changes affect every property, including its magnetic qualities.

One of the most prominent categories of ferrous metal products is steel. It is manufactured by rolling through cold-rolled and hot-rolled machines. The degree of fire resistance and ductility varies depending on the type of its production. If the sales process is taken under the influence of high temperatures, then the output is a raw material that can withstand severe climatic changes. The alloy produced under the influence of cold is characterized by increased flexibility and thermal conductivity.

Carbon steel is the basis for the production of smooth or corrugated stainless steel. It is universal, therefore it is actively used in various spheres of society:

• food industry;
• construction;
• heat and electricity;
• chemical and oil and gas industry;
• architecture;
• mechanical engineering and so on.

Magnetic properties

There are two types of steel products:

• Ferritic. The blanks of this group are magnetized. Additional alloying elements are copper, titanium and molybdenum. While maintaining its ductility, rolled metal has high strength. Intergranular corrosion is excluded.
• Austenitic. Physico-chemical phenomena due to the action of magnets are excluded. Used for the sale of kitchen products: containers, food industry equipment, frying pans, sinks. It is used in the medical field: needles are sold from such raw materials.

Moreover, the presence or absence of such a characteristic feature does not in any way affect the functionality of the material and its corrosion resistance. Both options have high anti-corrosion characteristics.

Can AISI 430 be magnetic or not? The answer is clear: yes, if it refers to ferritic metal structures. This means that its composition is dominated by chromium content and virtually no nickel and manganese.

Steel materials: features and differences

Regardless of the above feature, the coating of this brand can be of two types:

Each of them has its own processing technology. To make the surface shiny, reflecting everything around with maximum precision, long-term polishing is necessary. This allowed architects to create unique interior items and build modern buildings with an exclusive design.

To obtain a rough texture, grinding of the metal is required. A special tool with a coarse nozzle makes the coating darker, without glare, without a pronounced shine. The use of such rolled products is required for stamping parts and structures, which for the most part will be located inside installations and systems (in the design of a car or aircraft).

If you need a stainless pipe, strip, circle or wire, but the question arises about its additional parameters, you should remember that magnets do not react to the durability of the metal product and its external characteristics.

Source: https://www.globus-stal.ru/articles/aisi-430-magnititsya-ili-net-/

How to Determine Whether Magnetic or Non-Magnetic Steel is Stainless

Considering all of the above, we can draw the following conclusion: even if steel has magnetic properties, this does not mean at all that it cannot be classified as a stainless-type alloy.

There is a fairly simple way to check whether magnetic steel is stainless steel.

In order to determine this, it is necessary to clean the surface area of ​​the product being tested to a metallic shine, and then apply a few drops of concentrated copper sulfate to this area.

The fact that this is stainless steel is indicated by a coating of red copper that covers the cleaned area. This simple method allows you to very accurately determine whether magnetic steel is stainless. But it is almost impossible to check (and especially determine at home) whether stainless steel belongs to the food category.

If you decide to check whether magnetic steel is stainless or not, keep in mind that its properties, such as the ability to magnetize, do not in any way impair its corrosion resistance.

Source: http://met-all.org/metalloprokat/nerzhaveyushhij/nerzhavejka-magnititsya-ili-net.html

Food grade stainless steel: GOST. How to identify food grade stainless steel? What is the difference between food grade stainless steel and technical stainless steel?

Stainless steel is the most popular material from which containers and utensils that come into contact with food are made. Stainless steel has good anti-corrosion properties, durability and low weight. However, it is worth considering that this material is not always resistant to aggressive environments; in this case, special food-grade formulations are used.

Of course, it is best to store food in steel or glass containers, since the foam propylene that is popular today does not meet all the necessary requirements. In addition, its service life is much shorter than that of products made of steel.

Many people are interested in how to distinguish food-grade stainless steel from material that is unsuitable for storing food? To answer this question, it is worth considering the advantages, features and classification of this metal.

Advantages of food grade stainless steel

If we talk about the advantages of food-grade stainless steel, it is worth highlighting:

• environmental safety of the material;
• ease of maintenance;
• resistance of the material to most chemicals;
• wear resistance;
• compliance with standards for the dissolution of heavy metals.

In addition, it has long been proven that instead of frying pans with a non-stick coating, it is much healthier to use utensils made from food-grade stainless steel. The best cooking stoves and refrigerator surfaces are made from the same material.

Stainless steel, suitable for storing and preparing food, is a highly alloyed metal containing 25% chromium. It is thanks to this chemical element that alloys are famous for their anti-corrosion characteristics. In case of contact with an aggressive environment, a special protective film is formed on the metal surface. Thanks to this surface layer, the metal does not rust.

In addition, titanium, molybdenum, nickel and other chemical components are added to food-grade stainless steel, which further increase the anti-corrosion properties of the material.

GOST and stainless steel grades

If we talk about state standards, they do not stipulate the rules related to stainless steel. This is why experts find it difficult to answer which material is recommended for use in the food industry. In turn, the manufacturers of this stainless metal respond that regardless of its brand, it is suitable for food products.

Do the standards really say nothing about food grade stainless steel? GOST 5632-72 is perhaps the closest regulatory document that can be used when choosing the best alloy for household use. This State Standard refers to grades of high-alloy steel and corrosion-resistant and heat-resistant alloys. Let's take a closer look at this classification.

Austenitic, corrosion-resistant stainless steel is produced under this brand. The European analogue is AISI 304. This material is not magnetic. It is used in all industrial and commercial sectors.

This material has a low price and good quality. It is often used in the food industry, but only on the condition that the metal does not come into contact with caustic soda or sulfamine solutions.

12Х18Н10Т

The European analogue of this brand is AISI 321. This heat-resistant steel is also not magnetic. Stainless steel of this brand is often used in the manufacture of elements of furnace fittings, heat exchangers and exhaust manifolds. The thing is that this steel is suitable for use at high temperatures from 600 to 800 degrees.

08Х13

The European analogue of this material is AISI 409. This steel is widely used in the production of kitchen utensils and cutlery. This food grade stainless steel is most often found in stores. The material gained such popularity due to its high degree of adhesion and ability to adapt to different operating conditions.

This dish can be safely heated or stored in the freezer.

20Х13-40Х13

Steel of this type belongs to the category of composite materials, so it is often used in the manufacture of household and industrial sinks, as well as for the production of utensils for hygienic or thermal processing of food.

The European analogue of this brand is AISI 420. If the cookware bears one of these markings, then you can safely buy it for household use.

This stainless steel does not rust, tolerates sudden changes in temperature, and is also a fairly plastic and wear-resistant material.

12Х13

In Europe, this material is produced with the AISI 410 marking. Steel of this type is more often used in the production of equipment for winemaking, food processing and alcohol production. In addition, this material is characterized by increased heat resistance in mildly aggressive environments.

08Х17

In Europe, this steel is produced under the brand name AISI 430. This stainless steel is indispensable if the food in the cookware is subjected to heat treatment. This type of steel has the highest strength. However, this material quickly deforms in a sulfur environment. At the same time, stainless steel does not rust and can withstand mechanical loads. It is recommended to buy frying pans from this material, since 08X17 is characterized by a high thermal conductivity coefficient.

All other materials are used in special conditions, their cost is much higher. However, not all stainless steel can be safely used for cooking and storing food. In order not to delve into how food-grade stainless steel differs from technical stainless steel, it is much easier to read a few useful recommendations. They will allow you to quickly determine whether a given material is suitable for food. This is useful to know for every consumer concerned about their health.

How to distinguish food grade stainless steel from technical grade?

To determine the composition of the anti-corrosion alloy, as well as the possibility of its use in everyday life, you can write down the brands that were listed above. If such markings are on the utensils, then they are suitable for preparing and storing food.

But sometimes it happens that in front of your eyes is a material of an unknown brand, and the seller insists that this alloy is absolutely environmentally friendly and cannot harm humans. In this case, it is enough to place the metal in a 2% vinegar solution and wait for the reaction. If the shade of the material has changed, it has become dark, then it is better not to use it. The constancy of color indicates that the stainless steel is indeed food grade. It can be used.

There is another method that consumers often use after reading information on how to identify food-grade stainless steel. They use a magnet for this. But it is worth understanding that this method is completely ineffective, since stainless steel can be magnetic or non-magnetic. Accordingly, using a magnet will not help in any way determine whether the material can be used for food.

To choose the best metal, you should study the information about the product and ask the seller for accompanying documents. Any utensils must be manufactured in accordance with certain standards and requirements. If there is no marking on the product, then it is better to refuse such a product. Otherwise, you can purchase low-quality utensils that are dangerous to human health.

Source: https://FB.ru/article/321576/nerjaveyka-pischevaya-gost-kak-opredelit-pischevuyu-nerjaveyku-chem-otlichaetsya-pischevaya-nerjaveyka-ot-tehnicheskoy

Stainless steel that is magnetic - Is stainless steel magnetic or not: how to determine stainless steel

alexxlab | 03/10/2018 | 0 | Questions and answers

Is stainless steel magnetic or not: how to determine stainless steel

Considering the fact that stainless steel today is produced in a wide variety of brands, it is impossible to unequivocally answer the question of whether it is magnetic or not. The magnetic properties of stainless steels depend on the chemical composition and, accordingly, on the internal structure of the alloys.

A portable metal analyzer allows you to quickly determine the content of chemical elements and make a conclusion about the quality of stainless steel

Why is stainless steel magnetic?

One of the most popular types of rolled metal is heat-resistant stainless steel, grades of which are able to retain their properties at high temperatures, incl. in aggressive environments. Containers and equipment made from such alloys are effectively used for hot liquids, caustic acid solutions, and in the manufacture of parts for heating devices and boilers.

For the material itself, designations make it easy to determine the composition and purpose. For welding consumables such as stainless steel electrodes, the marking determines their use and classification:

• Consumable wire electrodes - copper, aluminum, steel, cast iron, etc.;
• Non-melting - tungsten, graphite (synthetic). Special coal is also used for electrical equipment;

Is stainless steel magnetic or not? Grades and properties of stainless steel

• March 27, 2019
• Miscellaneous
• Svetlana Pavlova

It is impossible to imagine the absence of anti-corrosion steel in modern life. The emergence of a stainless alloy made it possible to make great strides in many areas of the national economy. Only the addition of chromium to steel makes it resistant to corrosion. But when using it, consumers often have a question: is stainless steel magnetic or not? That's what we'll talk about in this article.

What is anti-corrosion steel?

Steel that does not become rusty during use is popularly called stainless steel. It is obtained from an alloy of iron with carbon and various alloying additives: nickel, chromium, niobium, titanium. Each of these components enhances or reduces certain properties of the alloy - magnetism, strength, hardness, ductility, corrosion. The main quality of stainless steel is corrosion resistance. It just depends on the chromium content in it.

The more of this metal in the alloy, the less susceptible it is to corrosion. Therefore, all steels that are resistant to rust contain at least 10.5% chromium. The uniqueness of this metal is that when it reacts with oxygen, it creates an oxide film on the surface of the product, which prevents the alloy from reacting with aggressive environments. Moreover, if the surface is damaged, the film forms again after the oxidation of chromium with oxygen.

Stainless steel classification

And yet, is stainless steel magnetic or not? Depending on the composition of chemical elements and internal structure, it can be magnetic or not, and is divided into the following types:

• Ferritic - contain more than 20% chromium, are resistant to aggressive environments, are endowed with magnetic properties, are affordable, and are widely used.
• Austenitic - do not corrode, contain large amounts of nickel and chromium, are flexible and durable. Easy to weld, belong to non-magnetic alloys.
• Martensitic - anti-corrosion alloys can be exposed to high temperatures, do not emit harmful fumes, and have increased wear resistance and strength.
• Combined - special stainless steels that combine the properties of all the above groups. Produced according to individual customer requests. The greatest demand is for austenitic-martensitic and austenitic-ferritic alloys.

It should be noted that the magnetic properties of steel do not affect its corrosion properties.

Magnetic properties of materials

All materials according to their magnetic properties are divided into:

• Paramagnets - tin, platinum, aluminum - increase the external magnetic field due to the coincidence of molecular currents with it.
• Diamagnets - copper, silver, zinc, their internal field weakens the external one.
• Ferromagnets - iron, cobalt, nickel, in which magnetization is greatly enhanced even under weak influence of an external field.

Why is stainless steel magnetic? This happens when the external magnetic field is strengthened by the internal one. Moreover, the more intensely they increase each other, the magnetization will be stronger. In addition, the magnetic properties of stainless steel depend both on the ratio of alloy additives that make up its composition, and on the phase state of the steel.

How to identify a stainless steel product?

Many consumers often try to determine on their own what metal a particular household item is made of. Visually, ordinary steel cannot be distinguished from stainless steel, so it is customary to use a magnet to check.

There is an opinion that real anti-corrosion steel is not magnetic. Can stainless steel be magnetic or not? Anything can happen. Therefore, this method of verification does not give a reliable result.

Sometimes it happens that a product is attracted to a magnet, but serves for a long time without changing its qualities.

And vice versa, which does not react to it in any way, upon contact with water it becomes covered with rust. Corrosion resistance can be correctly determined by examining its chemical composition, which is impossible to do at home. To protect yourself from counterfeits, it is better to purchase household products in branded stores.

Stainless steel that is not magnetic

Very often, alloys with a high content of chromium, nickel and manganese are used to produce anti-corrosion steel. They are used to produce a large number of different equipment and products for use in various fields. Non-magnetic steels include:

• Austenitic. They are used to make equipment for ships, refrigerators, the food industry, kitchen utensils and plumbing equipment.
• Austenitic-ferritic. The main advantages of such alloys are strength and increased resistance to cracking.

People most often in everyday life come across equipment and products made from these steels, so to the question “Is stainless steel magnetic or not?” and answer in the negative, although this is incorrect.

Anti-corrosion magnetic steels

Alloys that are resistant to rust but are strongly attracted to a magnet include:

• Martensitic - the material has high strength, can be ground and polished well, is very resistant to corrosion, and can be easily processed by stamping, cutting and welding. In addition to the manufacture of industrial equipment, it is used for the manufacture of cutlery. Therefore, the question of whether stainless steel is magnetic or not can be answered positively.
• Ferritic – the most popular grade of steel with magnetic properties is AISI 430, used for the production of food equipment.

Use of chromium-nickel steel

Anti-corrosion steel 12Х18Н10Т is an environmentally friendly and durable material.

The composition of the chromium-nickel alloy, in addition to the main component - iron, includes up to 19% chromium, which provides it with strong anti-corrosion properties, and 11% nickel, which transfers it to the class of austenites and imparts flexibility, strength and heat resistance.

Due to its characteristics, it is widely used. Many people are interested in whether steel grade 12Х18Н10Т is magnetic or not? It is non-magnetic, like all austenitic alloys, and is used in the following industries:

• Chemical - aggressive acids: acetic, nitric, phosphoric are transported through pipes made of this grade of steel.
• Food – dairy, meat, alcohol.
• Mechanical engineering – production of parts in contact with acids and alkalis, production of welded equipment, exhaust system manifolds.
• Petroleum - for the manufacture of pipes.

In addition, chromium-nickel alloys are used in the fuel and energy sector. Furnace fittings and heat exchangers are made from them.

Conclusion

Now you know which stainless steel is magnetic and which is not, and that these properties do not have any effect on the quality of the purchased product. At home, there is no way to check whether the dishes or plumbing equipment you purchased will rust or not. Everything will become clear during operation. To avoid making a mistake in your choice, make purchases at large retail outlets and from well-known manufacturers.

Source: https://truehunter.ru/458381a-nerjaveyka-magnititsya-ili-net-marki-i-svoystva-nerjaveyuschey-stali

Useful

Designation of alloying elements in stainless steels
The influence of the main alloying elements on the properties of stainless steels
Compliance of foreign standards with Russian GOST
Why is one brand of stainless steel magnetic and another not?
What is “Food Stainless Steel”?
The most common types of surface of stainless steel sheets

Designation of alloying elements in stainless steels

• In the initial part of the stamp there are numbers (two or one) showing the carbon content.
• Two numbers indicate its average content in the alloy in hundredths of a percent, and one – in tenths. There are also steels that do not have numbers at the beginning of the brand name. This means that the carbon content in these alloys is within 1%.
• The letters that can be seen behind the first digits of the brand name indicate what the alloy is made of.
• The letters that give information about a particular element in its composition may or may not be followed by numbers.

  If there is a number, then it determines (in whole percentages) the average content of the element indicated by the letter in the alloy, and if there is no number, it means that this element is contained in the range from 1 to 1.5%.

X - chromium
N - nickel
K - cobalt
M - molybdenum
B tungsten
T - titanium
D - copper
G - manganese
C - silicon
F - vanadium
P - boron
A - nitrogen
B niobium
E - selenium
C - zirconium
U - aluminum

Chromium (Cr):

• is the main element of steel, determining its resistance to oxidation (corrosion). Chromium sharply increases the corrosion resistance of steel when it increases in the alloy above 12.5%, starting from this concentration a dense oxide film of Cr2O3 is formed on the surface (chromium actually makes steel stainless, for example, steels 20Х13, 30Х13, 40Х13, etc.

  );

• when the chromium content in steel is 12-14%, the thermal conductivity of steel is 2 times less than pure iron, and the electrical resistance increases 3 times;
• provides increased strength at elevated temperatures, the addition of chromium increases the hardness and strength of steel without reducing its ductility;
• reduces the impact strength of steel.

Nickel (Ni):

• The main function of nickel is to stabilize the austenitic structure of steel; such a structure is especially strong and elastic. The minimum amount of nickel capable of stabilizing the austenitic structure is 8% (this is exactly how much nickel is found in the most common imported steel AISI 304);
• the presence of 8-10% nickel in steel provides it with good ductility and good forming properties;
• improves the weldability of steel and further increases the resistance of steel to oxidation (corrosion) in the weld area;
• nickel increases the heat resistance of steel (especially in relation to resistance to deformation);
• Thanks to nickel, stainless steel polishes better and is more scratch resistant than conventional steels (brushed and mirrored surfaces).

Molybdenum (Mo):

• increases the resistance of steel to oxidation (corrosion) at high temperatures, reduces the resistance of steels to pitting corrosion;
• increases red resistance, elasticity, tensile strength;
• provides additional thermal strengthening.

Titanium (Ti):

• increases the strength of steel;
• Titanium is added to stainless steels to prevent intergranular corrosion.

Carbon (C):

• with an increase in carbon to 0.8%, the hardness and strength of the steel increases, but leads to an increase in the threshold of cold brittleness (for example, steels 40Х13 and 95Х18 are used for the production of knives);
• the more carbon there is in the steel, the more difficult it is to process by cutting, the worse it deforms and the worse it welds (for example, the most common commercially available imported steels of the 300 series AISI304/321/316 have 0.8% carbon in their composition, which gives them a wide range of applications compared to domestic steel 12x18n10t).

Compliance of foreign standards with Russian GOST.

Currently, almost all stainless steel products supplied to our country are marked according to AISI, DIN, or EN standards. Let's consider the compliance of these standards with Russian GOST.

AISI (American Iron and Steel Institute), American Institute of Iron and Steel

The designation of standard stainless steels according to AISI includes three numbers followed by one, two or more letters in some cases. The first digit of the designation determines the steel class.

Thus, the designations of austenitic stainless steels begin with the numbers 2XX and 3XX. While ferritic and martensitic steels are defined in class 4XX.

Moreover, the last two digits, unlike carbon and alloy steels, are in no way related to the chemical composition, but simply determine the serial number of the steel in the group.

The additional letters and numbers following the numbers used to designate AISI stainless steels mean:

xxxL – Low carbon content < 0.03%xxxS – Normal carbon content < 0.08%xxxN – Added nitrogenxxxLN – Low carbon content < 0.03% + added nitrogenxxxF – Increased sulfur and phosphorus contentxxxSe – Added seleniumxxxB – Added siliconxxxH – Extended range of carbon content

xxxCu – Copper added

For example:

Steel 304 belongs to the austenitic class, the carbon content in it is

Source: https://nergspb.ru/useful/