How can you identify stainless steel?

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:

• paramagnetic materials – 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.

Ferritic

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

Martensitic-ferritic

A popular brand of magnetic stainless steel, the internal structure of which consists of martensite and free ferrite, is 12X13.

Corrosion resistance of steel grade 12Х13 (other name 1Х13)

Non-magnetic stainless steels

Stainless steels that are not magnetic include chromium-nickel and chromium-manganese-nickel. They are usually divided into several groups.

Austenitic

The most popular brand of such stainless steels, which occupy a leading place among non-magnetic steel alloys, is 08Х18Н10 (international analogue according to AISI 304 classification).

Steels of this type, which also include 08Х18Н10, 08Х18Н10Т, 12Х18Н10Т, 10Х17Н13М2Т, are actively used in the production of equipment for the food industry; kitchenware and cutlery; plumbing equipment; containers for food liquids; refrigeration equipment elements; containers for food products; medical supplies, etc.

Composition and application of austenitic steels

The great advantages of such stainless steel, which does not have magnetic properties, are its high corrosion resistance, demonstrated in many aggressive environments, and manufacturability.

Austenitic-ferritic

Steels of this group, the most popular grades of which are 08Х22Н6Т, 08Х21Н6М2Т and 12Х21Н5Т, are distinguished by a high chromium content and a low nickel content. To give such a stainless steel the required characteristics (an optimal combination of high strength and good ductility, resistance to intergranular corrosion and stress-corrosion cracking), elements such as copper, molybdenum, titanium or niobium are introduced into its chemical composition.

Chemical composition of some industrial grades of austenitic-ferritic steels (click to enlarge)

In addition to the above, stainless steels that are not magnetic include alloys with an austenitic-martensitic and austenitic-carbide structure.

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

How to distinguish stainless steel from other metals

How to distinguish one steel grade from another if, for example, AISI 304 and AISI 303 sheets were stored together? A number of simple, inexpensive and non-damaging tests can help solve this problem. It should be noted right away that such tests have a number of serious limitations.

For example, such tests will not help determine which of two sheets of steel of the same grade has been heat treated and which has not. Additionally, there is no easy way to distinguish certain grades of steel from each other. For example, it is impossible to distinguish steel AISI 304 (08Х18Н10) from AISI 316L (03Х17Н14М3), or 304 (08Х18Н10) from 304L (03Х18Н11).

A molybdenum content test will help determine whether molybdenum is present in steel, but without additional information the grade of steel cannot be correctly determined. For example, AISI 316 (10Х17Н13М2) steel, based solely on the results of this test, can be defined as 316L (03Х17Н14М3), 2205 or 904L.

Often, only with the help of more complex tests, in which the metal is exposed to chemical reagents, strength or heat resistance is checked, can the grade of steel be reliably determined. If simple tests do not help, then a full spectral or chemical analysis in the laboratory cannot be avoided.

Reaction to magnet

This test will help determine that austenitic steels (for example, AISI 300 series) do not react to a magnet when approaching it. Other stainless steels, such as ferritic, martensitic and duplex, react to magnets. When performing this test, it should be remembered that some austenitic steels, for example, 304 (08Х18Н10), can be attracted by a magnet if they were produced by cold rolling.

Reaction to nitric acid

Helps differentiate carbon steel from stainless steel. First, you need to place a steel sample in a solution of nitric acid (from 20-50%) at room temperature, or drop the solution onto a clean steel surface. A reaction will begin on the surface of the carbon steel, releasing caustic brown vapor. This reaction does not occur with stainless steel. When working with nitric acid, you must be extremely careful, and you should not inhale the vapors released during the reaction.

Molybdenum content test

Helps determine whether steel contains molybdenum. Steel containing sufficiently molybdenum, for testing as follows: 316 (10x17n13M2), 316L (03x17N14M3), 444, 904L, 2205, all "super -duplicate" alloys (S32760, Zeron 100, S32750, 2507, S32550, S32520, UR52N+). The test can also determine molybdenum in other steels containing approximately 2% Mo.

When conducting a test, it is best to compare an unknown steel with a control sample, for example, AISI 304 (08Х18Н10) and AISI 316 (10Х17Н13М2) steels. For the test you will need an acid-based reagent (you can use either the American “Decapoli 304/316” or “Moly Drop 960”, or domestic analogues, although they are quite difficult to find).

First, it is necessary to prepare the surface of the test sample by cleaning it with sandpaper. Then drop the reagent onto the surface of the steel to be determined and onto the control sample. Dark yellow spots appearing after 2-4 minutes indicate the presence of molybdenum. When carrying out the test, do not forget that its reliability may be affected by the temperature of the samples.

For example, some steels containing about 0.5% molybdenum in impurities may react positively to the test at low temperatures. During the test, you should be careful when working with the reagent and follow the requirements for safe work with acids.

Sulfur content test

Sulfur is a harmful impurity that causes brittleness of steel during hot forming. This test helps determine the level of sulfur in steel. For this test, control samples of AISI CS1020, S1214, 304 or 303 steels will be needed, comparison with which will help in determining the degree of sulfur content. To carry out the test, it is necessary to clean the surface of the test sample using sandpaper, and control samples should be prepared in the same way.

Next, you should soak the photographic paper in a 3% sulfuric acid solution for 3 minutes, apply the photographic paper face to the surface of the test sample, hold for 5 seconds and compare the results of the tested steel and the control samples. A dark brown stain indicates high sulfur content. When testing, it should be taken into account that the reliability of the result is seriously influenced by the density and duration of contact of the paper with the surface.

When performing this test, also remember to be careful when working with acid.

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Source: http://ooo-asteko.ru/kak-otlichit-nerzhaveyku-ot-drugih-metallov/

How to identify stainless steel at home - Metals, equipment, instructions

31.10.2017 16:13

The material in question presents ten ways to distinguish aluminum from stainless steel.

Some of them are very easy to use at home, without having absolutely any tools, equipment or chemicals.

This will allow you to quickly and accurately determine the value of a particular item (product) made of aluminum or stainless steel.

1. Magnet

Unfortunately, it is not always possible to reliably distinguish these two metals from each other using a magnet. The fact is that any brand of aluminum, one way or another, does not stick to the magnet. But not all stainless steel has the same property.

If the product under study is magnetic, then it is definitely not aluminum. The sample may refer to stainless steels that contain sufficient amounts of nickel. If copper or chromium predominates in stainless steel, then it will not react in any way to a magnet.

2. Marking

As a rule, some stainless steel products have appropriate markings that allow you to accurately identify the item being examined. In this case, everything is quite simple. Inscriptions like “STAINLESS” and other similar ones are a clear sign that this is definitely not aluminum.

3. Plain paper

One of the easiest ways to determine the difference between aluminum and stainless steel. For the experiment you will need a sheet of plain paper. It must be white paper. The one used for printer printing is suitable. The denser it is, the better for the business.

The essence of the experiment is as follows. First, you need to clean the edge of the product under study from dirt, grease, oils and other deposits. Next, you need to move this place along a sheet of white paper. The pressing force should be as strong as possible. It is very easy to draw conclusions. Stainless steel on a white sheet will not leave any marks, while aluminum will show thin stripes of gray color.

4. Metal color

Another criterion that more or less clearly distinguishes stainless steel from aluminum is the shade of the product in question. If we have stainless steel in front of us, then its surface, as a rule, has a shiny, colorless tint. However, over time this condition persists.

If we consider an aluminum product, then the color of its surface is usually matte (this metal is difficult to polish to a glossy shine), gray or whitish. After processing with sandpaper, the sanded area will quickly become covered with an oxide film and become dull.

5. Mechanical loads

This is also a fairly simple method that can be done at home. Its essence lies in the fact that the product under study must be hit against a solid metal object. To obtain a more accurate and visual result, this should be done in the dark.

If the product is made of stainless steel, then we will see quite pronounced sparking upon impact. It can be seen even in dim lighting. In the case of aluminum, there will be no sparking, even if you look very carefully in complete darkness.

6. Thermal conductivity and melting

In the case of various containers, metal can be determined by heating. So, in an aluminum pan, ordinary water is brought to a boil quite quickly. Under the same conditions (volume of water, heating) in a stainless steel container, this process takes much longer. This is due to the fact that the thermal conductivity of aluminum is many times better than that of steel.

The melting point of aluminum is about 660°C, while for stainless steel this indicator is beyond 1800°C.

When using a conventional gas burner, which is used as camping equipment, it is quite easy to reach a temperature of 700°C.

This means that it is also possible to melt a small aluminum object on such a fire. Stainless steel cannot be melted under normal conditions (without pressurization and oxygen supply).

7. Copper sulfate

An excellent and quite affordable option for determining aluminum or stainless steel is to expose the metal to a solution of copper sulfate. It is sold in agricultural stores at a low price. When processing this material, cloudy marks and stains will certainly remain on aluminum. Vitriol has no visible effect on stainless steel.

8. Lye

Alkaline solutions are also quite accessible today, and help to easily distinguish between these two metals. It can be sodium or potassium hydroxide. As in the case of vitriol, aluminum reacts to treatment with alkali, as a result of which brown spots remain. If the product being examined is made of stainless steel, we will not find any visually visible traces.

9. Acid

For a successful experiment, a solution of citric acid or lemon juice will be sufficient. A more pronounced result will be obtained when the metal is exposed to more aggressive acids. The essence of the definition is the same as with vitriol and alkali. External processing will leave stains on the aluminum surface. Stainless steel does not react with acids.

10. Density

The longest and most difficult way to distinguish the two metals in question is to determine their specific density. This is only applicable for small products, as well as for those that have a regular geometric shape. The bottom line is that you first need to calculate the volume of the sample under study, and then, using a simple formula, find out its specific gravity.

The result obtained is ultimately compared with fixed density values. For aluminum this figure is about 2.6 g/cm3, while stainless steel is almost three times denser - from 7.6 to 8.1 g/cm3.

Source: https://spb-metalloobrabotka.com/kak-opredelit-nerzhaveyuschuyu-stal-v-domashnih-usloviyah/

How to distinguish stainless steel from aluminum

One of the most popular types of metal in production is aluminum. It is often used to make household products. To determine exactly what kind of metal you have, use these tips and perform a few simple tests.

1. The easiest way is to use a magnet. Aluminum is paramagnetic and practically non-magnetic. Even a child can carry out a test using a magnet at home.
2. Using a plain piece of paper. To carry out the test, you will need to remove dirt from the surface of the object being tested and run it with paper, pressing firmly on the product. If you have stainless steel in front of you, then there will be no traces left on the sheet, but with aluminum, gray stripes will appear.
3. Another criterion for distinguishing stainless steel from aluminum is the color of the metal. If the surface is smooth and shiny, then this is stainless steel; aluminum has a matte surface without a characteristic shine.
4. Thermal conductivity indicators. To install metal accessories, simply pour water into a container and bring to a boil. In aluminum cookware, water will boil much faster, since the thermal conductivity of this metal is much higher.
5. Separately, we can distinguish chemical methods for determining stainless steel using various acids and alkalis. When treating aluminum with alkali, brown spots remain on the surface; stainless steel will not have any visible changes.
6. Exposure to copper sulfate. You can find this reagent in any agricultural store. After application to the aluminum surface, cloudy stains will certainly remain. Vitriol has no effect on stainless steel.

Using these methods will allow you to determine at home with 100% accuracy where the product is made of aluminum and where it is made of stainless steel.

How to distinguish stainless steel from other types of steel

In appearance, all steel grades are almost identical, but at the same time they have different technical characteristics. This means that products made from different types of steel behave differently. To distinguish stainless steel from another grade of steel, you can use several methods:

• Use of nitric acid. This chemical liquid helps distinguish stainless steel from carbon steel. If you apply a few drops to the surface of the steel, a reaction will begin in which caustic steam will be released. This reaction is typical for carbon steel; no changes will occur with stainless steel.
• Check the reflection on the surface. Stainless steel has bluish-yellow tints on its surface.
• Marking. Steel products are always marked with the type and grade of material used. If the numbers are preceded by the letters “STAINLESS”, this means the use of alloy steel.

These simple tips will help you accurately determine the presence of stainless steel.

How to distinguish stainless steel from non-ferrous metals

It is difficult for an ignorant person to separate stainless steel from non-ferrous metals. This will require complex chemical actions and reagents. Still, you can use some expert advice:

1. Take a small piece of the sample and drill a hole. In duralumin, the chips move away in a spiral and do not stick to the drill.
2. Hydrogen peroxide and 20% sodium sulfide can be used. When these reagents are applied to a cut, the surface of non-ferrous metals will darken.

Distinctive characteristics of food grade stainless steel from technical grade

It must be said that the division of stainless steel into two types has a special character, since they differ in areas of use. The main difference between them is the surface treatment. For the food type, the surface is of particular importance, since the metal will come into contact with food products.

Distinctive features of food grade stainless steel are a smooth surface with a high level of processing. Food grade stainless steel is a highly alloyed metal that is resistant to corrosion and rust. The amount of additives affects the quality of product operation. The food grade is susceptible to the influence of an aggressive alkaline environment, so it adds more metal impurities. Based on the composition and markings, you can accurately determine what type of stainless steel it is.

Results

To determine the type of metal and the distinctive features of stainless steel, it is enough to know the basics of chemistry and some characteristics of metals. By conducting simple chemical experiments or using simple household methods for installing stainless steel products, you can easily determine what type of metal was used.

We also recommend reading:

Raw materials from which aluminum is produced

Aluminum pipes: properties and applications

Corrugated Aluminum Sheet: Applications

Source: https://aluminiypro.ru/kak-otlichit-nerzhavejku-ot-drugih-metallov

How to identify food grade stainless steel at home?

Stainless steel or in common parlance “stainless steel” is used by people for various purposes, because it is a metal often used in everyday life. Reasonable price and good quality have made this type of product popular among the population.

Stainless steel products are the main attributes of everyday life and have entered the life of every person seriously and for a long time. Stainless steel is used not only in everyday life, but also in production.

It’s safe to say that food-grade and regular stainless steel is an important element of human life.

What is the difference between food grade stainless steel and technical stainless steel?

The difference between these two types is the coating on the surface of the industrial steel and how it is processed.
For food grade steel, it is important what kind of surface the food will touch. The surface polished to a mirror shine is typical for the food version of stainless steel; the technical version has a matte surface.

Technical steel differs from food steel in the following ways:

1. Different surface coating.
2. Different levels of surface treatment.

What is food grade stainless steel?

The name speaks for itself: you need steel that will not rust with prolonged or moderate contact with food. Therefore, the dishes must be made from appropriate material. Food grade steel is the best choice, combining availability, reliability and quality.

It is necessary to pay attention to the fact that the concept of “food grade stainless steel” does not officially exist in the state standard and is used only in everyday life.

Food grade stainless steel

Stainless steel is a highly alloyed metal and is therefore resistant to corrosion. Chromium added to the metal allows it to not rust. The amount of alloying additives determines the corrosion resistance.

Molybdenum, titanium, and nickel also significantly improve the protective properties of steel. The conditions in which stainless steel is used are decisive for it.

In the food industry, equipment is affected by an aggressive environment, and therefore it is important what metal it is made of.

If there is a need to learn about food grade or technical stainless steel, you should conduct an experiment. The material to be tested must be placed in vinegar and kept there for some time. Darkening of the sample indicates that it is technical steel; preservation of the color indicates food grade stainless steel.

Stainless steel is used in various areas of production. Its cost directly depends on the brand, sheet size, and ability to withstand various environmental influences. Currently, one of the developing areas is the sale of nickel-free steel. Cutting objects, in particular knives, are made from such steel. The steel was called “technical stainless steel”.

Technical stainless steel

12Х18Н10Т grade of steel sheets is in demand and is a product of a domestic manufacturer. Food grade stainless steel is also produced abroad, demonstrating decent quality. In order to determine how much a sheet costs, you need to know its parameters. Stainless steel sheets produced abroad have the following types of surfaces:

• Matte.
• Mirror.
• Sanded.

They are in demand, which is important for the development of production.

Where is food grade steel used?

In the food industry, there is a need to select a material that will come into contact with food. This choice must be approached with special responsibility.

Negative interactions are possible during food storage and transportation. Even high-quality stainless steel does not in all cases have the ability to withstand the effects of materials.

In such cases, it is possible to use special food alloys that have special requirements.

Alloys are used in the food industry and are capable of not reacting to aggressive influences. Every kitchen has stainless steel cookware, which pleases its owners with reliability and practicality. The surface of the electrical equipment is made of stainless steel. All this is convenient to use, has a long service life and excellent quality.

For use in everyday life and in production, choose stainless steel, which will be in close contact with food, and therefore must be of high quality.

Special alloys are used to make equipment that is not susceptible to any external influences. The most popular and cheapest grade of stainless steel is 08Х18Н10 (AISI coding – 304).

This alloy is excellent for use in the food industry and catering plants.

08Х18Н10

How to choose a grade of food grade stainless steel: types and scope of use of food grade stainless steel

The production of equipment or containers that interact with food requires the selection of a specific material. Preparation, storage, transportation of food, sanitation, are most often associated with conditions where even stainless steel can be susceptible to corrosion and negatively affect the quality of food. The so-called food grade stainless steel helps solve this problem.

Food grade stainless steel is a general name for grades of stainless steel that have increased corrosion resistance . GOST does not have this definition; it is for this reason that food grade stainless steel often needs to be selected based on scattered reviews and information. What is food grade stainless steel, and how to choose the right grade of steel? First things first.

  How to properly cook stainless steel with electrodes?

Why do you need food grade stainless steel?

The manufacture of various containers and utensils that come into contact with food products involves the selection of special materials that have special properties. Since even ordinary stainless steel, which is famous for its anti-corrosion properties, cannot always withstand aggressive chemical processes that are related to the food industry .

In these cases, the issue is resolved by using specialized food grade stainless steel compounds. It is these alloys that are best suited for the manufacture of various types of equipment for processing and storing food.

These compositions meet the highest requirements (toxicological, hygienic, aesthetic) for metals that can be used in the food industry.

Advantages of food grade stainless steel:

• environmentally friendly;
• easy to maintain;
• not afraid of most chemical environments;
• wear-resistant;
• complies with clear rules for the dissolution of heavy metals in working environments.

Stainless steel is rightfully one of the best materials for making cookware that is used in everyday life.

No housewife will refuse a beautiful frying pan made of this steel, a saucepan, quite practical and elegant cutlery, and any other kitchen utensils.

The surfaces of refrigerators, cookers, and so on are made from stainless steel. Today, the number of uses of stainless steel products in everyday life is constantly growing.

Manufacturers of various products and catering establishments install stainless pipes . They are also used for the manufacture of technological devices used at all stages of the food preparation process - for preparing and grinding raw materials, mixing, cooking, transporting, separating and sorting.

Which stainless steel compounds are food grade?

By “stainless steel” we usually understand a large range of high-alloy metals containing a fairly large amount of chromium (about 25 percent).

It is this chemical element that gives the alloys anti-corrosion characteristics due to the fact that upon contact with an aggressive environment it forms a special protective film on the steel surface.

This protective layer prevents the metal from rusting because it contains insoluble oxides.

To increase anti-corrosion properties and give metals special characteristics, other chemical elements (nickel, titanium, molybdenum, etc.) are added to stainless steel, which change the properties of the alloy.

For example, in mildly corrosive environments, you can use stainless steel at a chromium ratio of approximately 14-18 percent without worrying about rusting.

If you add a little chromium (make its amount less than 18 percent), as well as molybdenum and nickel, then this metal composition can already be used in saline solutions and other rather aggressive liquids.

In our country, there are no separate State standards and rules for “food grade stainless steel”. It is for this reason that most people find it difficult to answer which brands of stainless steel can be classified as “food grade” and which cannot.

Experts say that almost all stainless compositions existing today can, purely theoretically, be classified as those that are suitable for preparing or storing food products.

In this case, the main thing is to decide on the rules for their operation .

Source: https://varimtutru.com/kak-opredelit-pischevuyu-nerzhaveyku-v-domashnih-usloviyah/

Food grade stainless steel: steel grade, application, advantages

Food grade stainless steel, as stainless steel is abbreviated to be used for the production of products that come into contact with food and liquids during their operation, is a material with a special chemical composition. The properties of this metal, represented by various grades, determine a fairly wide scope of its application.

Stainless steel sheet grade 08Х18Н10 (AISI 304) polished in film

Surface quality and roughness

For the food industry, the surface of the metal is important. AISI provides the following types of surface treatments:

• 1D - hot rolled, pickled and heat treated. The surface has a matte sheen and is slightly rough.
• 2B – cold rolled, pickled, heat treated and tempered. Characterized by a matte surface, high smoothness and gloss with gloss. One of the most common in modern industry.
• BA – cold rolled, using special rolls, followed by bright annealing. Has a mirror surface.
• 4N - polished stainless steel surface in various ways.
• PE - sheet metal has a protective film on one side.

Interesting information: How to identify the difference. If there is a need to test stainless steel, it is necessary to place the sample in a saline or 2% vinegar solution and leave for several days. If the steel has not darkened, it can be used for production. The second method is to sand an area of ​​metal with sandpaper and apply a solution of copper sulfate to this place. The absence of a red film indicates that the alloy belongs to stainless steel grades.

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.

What is “technical stainless steel”?

Stainless steel is used in various areas of production. Its cost directly depends on the brand, sheet size, and ability to withstand various environmental influences. Currently, one of the developing areas is the sale of nickel-free steel. Cutting objects, in particular knives, are made from such steel. The steel was called “technical stainless steel”.

Technical stainless steel

12Х18Н10Т grade of steel sheets is in demand and is a product of a domestic manufacturer. Food grade stainless steel is also produced abroad, demonstrating decent quality. In order to determine how much a sheet costs, you need to know its parameters. Stainless steel sheets produced abroad have the following types of surfaces:

• Matte.
• Mirror.
• Sanded.

They are in demand, which is important for the development of production.

Operational Requirements

During the manufacture and use of equipment, steel is exposed to all kinds of influences. There is a danger of changes in the surface structure, which leads to a deterioration in the declared indicators and a decrease in performance characteristics.

Compliance with the following requirements for the production and operation of food grade stainless steel products will extend their life and be safe when preparing any food, in any quantity.

• During design and production, contact of dissimilar metals must be avoided. If such contact is unavoidable, insulating gaskets should be used.
• Products intended for designated industries must be designed and manufactured without narrow, difficult-to-reach cavities. Such defects lead to the retention of various substances and will allow the residues of cleaning and washing chemicals to concentrate. This fact explains why welds must be butt welds. Overlapping connections of elements are strictly prohibited.
• If there is no urgent need, minimize the time of interaction of steel with high-temperature concentrates that contain sodium chloride, solutions containing acids, even at low temperatures, disinfecting and cleaning chemicals based on chlorine.
• Avoid food drying on metal surfaces, regardless of the nature of the food. Even neutral food can turn sour and acids will appear that destroy the surface.

From the information presented on this page, we can conclude that before choosing a specific grade of stainless steel for the manufacture of food industry equipment, it is necessary to conduct research and examination of the sample under conditions close to those in which it will have to be used.

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.

Selection of popular stainless steel grades

For use in everyday life and in production, choose stainless steel, which will be in close contact with food, and therefore must be of high quality. Special alloys are used to make equipment that is not susceptible to any external influences. The most popular and cheapest grade of stainless steel is 08Х18Н10 (AISI coding – 304). This alloy is excellent for use in the food industry and catering plants.

08Х18Н10

Areas of application

As previously noted, the scope of application of stainless steel has been significantly expanded. Stainless steel grade for the food industry can be used in the production of the following products:

1. Cutlery and crockery.
2. Various electrical goods intended for cooking.
3. Equipment for the food industry: storage, transportation, preparation.
4. In some cases, sheets of metal are used to line the interior surface of the cargo compartment of a vehicle.

Stainless steel teapot

Stainless steel kitchen set

The composition can include a variety of chemical elements, due to which not only corrosion resistance increases, but also strength and hardness.

How to identify stainless steel at home - Metalworker's Guide

How to distinguish one steel grade from another if, for example, AISI 304 and AISI 303 sheets were stored together? A number of simple, inexpensive and non-damaging tests can help solve this problem. It should be noted right away that such tests have a number of serious limitations.

For example, such tests will not help determine which of two sheets of steel of the same grade has been heat treated and which has not. Additionally, there is no easy way to distinguish certain grades of steel from each other. For example, it is impossible to distinguish steel AISI 304 (08Х18Н10) from AISI 316L (03Х17Н14М3), or 304 (08Х18Н10) from 304L (03Х18Н11).

A molybdenum content test will help determine whether molybdenum is present in steel, but without additional information the grade of steel cannot be correctly determined. For example, AISI 316 (10Х17Н13М2) steel, based solely on the results of this test, can be defined as 316L (03Х17Н14М3), 2205 or 904L.

Often, only with the help of more complex tests, in which the metal is exposed to chemical reagents, strength or heat resistance is checked, can the grade of steel be reliably determined. If simple tests do not help, then a full spectral or chemical analysis in the laboratory cannot be avoided.

Tests for determining the grade of stainless steels

How to distinguish one steel grade from another if, for example, AISI 304 and AISI 303 sheets were stored together? A number of simple, inexpensive and non-damaging tests can help solve this problem. It should be noted right away that such tests have a number of serious limitations.

For example, such tests will not help determine which of two sheets of steel of the same grade has been heat treated and which has not. Additionally, there is no easy way to distinguish certain grades of steel from each other. For example, it is impossible to distinguish steel AISI 304 (08Х18Н10) from AISI 316L (03Х17Н14М3), or 304 (08Х18Н10) from 304L (03Х18Н11).

A molybdenum content test will help determine whether molybdenum is present in steel, but without additional information the grade of steel cannot be correctly determined. For example, AISI 316 (10Х17Н13М2) steel, based solely on the results of this test, can be defined as 316L (03Х17Н14М3), 2205 or 904L.

Often, only with the help of more complex tests, in which the metal is exposed to chemical reagents, strength or heat resistance is checked, can the grade of steel be reliably determined. If simple tests do not help, then a full spectral or chemical analysis in the laboratory cannot be avoided.

What affects the price of stainless steel, how to determine stainless steel

Scrap of non-ferrous, rare earth metals,
battery, cable scrap.

Stainless steel or stainless steel is part of the group of alloy steels and may include impurities that are designed to improve its characteristics: hardness, resistance to aggressive environments, corrosion and high temperatures.

What can be scrapped?

Stainless steel scrap collection centers are ready to accept:

• pipes;
• sheets;
• shavings;
• dishes;
• cutlery;
• metal scraps;
• springs and other metal parts, and finished stainless steel products.

What affects the price of scrap?

The main evaluation criterion in the process of accepting stainless steel scrap is the percentage of nickel and chromium. The more nickel there is in a metal, the more expensive it is.

The price of scrap is also affected by:

• Appearance and condition of the metal. The presence of rust will reduce the initial cost of scrap. And loose rust is the first sign of low quality metal.
• Magnetic properties. Products that are not magnetic will cost more.
• Density and durability of paintwork. A strong paint layer complicates the metal cleaning procedure, therefore reducing the cost of scrap.
• Number of metal layers. Multilayer steel is less in demand, so its price will be lower.

How to quickly determine the quality of stainless steel

The cost of stainless steel directly depends on its quality. You can determine the quality of steel:

• on low-quality stainless steel, a drop of water leaves a yellowish stain;
• Salt will also help check the quality of the metal. On the surface of high-quality alloys, salt leaves no traces after drying;
• high quality metal produces a short, direct spark.

nickel in various metal objects

The percentage of nickel in stainless steel is classified:

• nickel 2-5% - may be contained in sanitary waste objects;
• nickel 10% - present in kitchen utensils;
• nickel 12% - found in plates, metal scraps, construction waste and other heat-resistant materials;
• nickel 30-85% - metal alloys (matte);
• nickel 95% - present in construction and plumbing rings, connectors, wire, powder, scrap and other high-alloy steel.

How to distinguish stainless steel from other metals

Taking into account the fact that stainless steel may or may not have this property, there is no need to focus on this indicator.

Therefore, in order to distinguish stainless steel from scrap of other metals, you need to clean a small area of ​​the surface of the object being tested until the metal shines, then use a few drops of concentrated copper sulfate applied to the scrap.

Stainless steel under the influence of vitriol will become covered with a coating of red copper. It is almost impossible to determine whether a stainless steel belongs to the food category without special devices.

How to hand over stainless steel in Moscow

The procedure for accepting stainless steel in Moscow by MDM-Vtormetall is aimed at maintaining the interest of the donating party:

• collection points are located in different parts of the city;
• We provide pick-up service at any convenient time;
• We provide free consultations;
• We are considering the possibility of dismantling the facility ourselves.

Our scrap metal collection center tries to offer the most favorable prices for receiving stainless steel.

Use in medicine

This alloy, due to its high hygienic properties, rigidity, wear resistance and ease of cleaning from various contaminants, including bacteriological

Architectural and construction elements

Today, stainless steel, due to its hygienic properties, high strength and corrosion resistance, is used everywhere, including in architecture.

Bar equipment

In bars, like in any dining room, there is a kitchen where you can find a lot of different stainless steel equipment. But this article will talk about equipment for

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Source: http://www.mdm-vtormetall.ru/stati/interesnoe-o-nerzhavejke/podrobnosti-o-lome-nerzhaveyushhej-stali.html

How to distinguish food grade stainless steel from technical grade

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When creating products that may come into contact with food and liquids during operation, food grade stainless steel is often used. The properties of this material determine its wide distribution. The main property is related to corrosion resistance. A wide variety of blanks are supplied for sale, most often in the form of sheets.

General characteristics of food steel

The main characteristics of food grade stainless steel are higher than regular ones. This is due to the fact that not every metal can withstand the conditions under which food is transported and stored. That is why, over a long period, developments have been carried out to obtain a material with exceptional performance qualities.

Modern food grade stainless steel is characterized by the following features:

1. Aesthetically attractive appearance. However, it remains practically unchanged over a long period.
2. The differences between food-grade stainless steel and technical stainless steel are that the former is produced in compliance with strict hygienic and toxicological requirements.
3. Environmental Safety. The surface does not interact with the environment.
4. Ease of maintenance. Stainless steel can be cleaned quickly if necessary and does not require special chemicals.
5. The surface film can withstand aggressive influences.

Recently, food grade steel is often used in the manufacture of household products. In addition, sheet material is used for lining the interior of ovens or stoves. High performance characteristics determine that stainless steel can last for a long period.

Food grade stainless steel sheet

A fairly common question is how to distinguish food grade stainless steel from technical grade stainless steel. The category of metals under consideration includes alloys that contain about 27% chromium.

By increasing the concentration of this chemical, an oxide film is formed on the surface, which significantly increases the corrosion resistance of the metal.

How to identify food grade stainless steel? As a rule, the difference lies in the concentration of certain elements in the composition:

1. At a certain concentration of chromium and calcium, the resistance of the surface to water vapor can be increased. At the same time, anti-corrosion properties can be maintained at temperatures up to 1150 °C.
2. The composition may also include nickel, which increases the resistance of the surface to nitric or other acids.
3. Molybdenum increases the resistance of the metal to acetic and sulfuric acid.
4. In some cases, copper is added, due to which the metal becomes more resistant to corrosion and stretching.
5. Silicon protects the material from the action of sulfuric and hydrochloric acid.

It is worth considering that a high concentration of alloying elements can negatively affect the basic mechanical characteristics of the metal. Therefore, when choosing a more suitable stainless steel, the conditions under which it will be used are taken into account.

Popular brands

When choosing the most suitable alloy, attention is paid to how long the product will be in contact with an aggressive environment. Some products can be created from an alloy that is less resistant to corrosion, but still has good strength.

Food grade stainless steel steel grade AISI 304 is the most widely used. This is due to the fact that 08×18N10 is characterized by low cost and high resistance to various chemicals and substances. In addition, the following qualities are taken into account:

1. A good degree of weldability, which simplifies the process of producing various products.
2. High strength and increased machinability with low heat.
3. It is possible to carry out electric polishing to obtain the highest quality surface.
4. High resistance to intercrystalline corrosion. It can significantly reduce the strength of the material and its other qualities.

Another popular brand of food grade stainless steel 08×13 is characterized by universal properties. It is used in the manufacture of various products, including those used in everyday life. A heat treatment container is often created using a 20×13 grade, which is characterized by ductility and increased wear resistance. In addition, when exposed to heat, the surface does not lose its corrosion resistance.

Industries that require metals with increased corrosion resistance include winemaking or alcohol production, and waste recycling. In this case, steel grade 12×13 is used. It is characterized by the following properties:

1. High heat resistance. During operation, stainless steel can heat up to temperatures above 100 °C, due to which the basic properties change.
2. Protection from exposure to mildly aggressive environments.
3. Good toughness

Stainless steel is often used in the manufacture of containers for industrial and household purposes, in which food is heated to high temperatures. The 08×17 brand is suitable for this. This alloy has the following properties:

1. Corrosion resistance at elevated temperatures. Some food-grade stainless steels cannot withstand high heat, resulting in corrosion on the surface.
2. High mechanical properties. The created products can last a long time under various operating conditions.
3. Thermal conductivity. As a rule, heating of the contents occurs from the outside. That is why thermal conductivity is considered the most important parameter.
4. With sufficient strength, high ductility is also maintained.

Chemical composition of food grade stainless steel 20X13

Universal ones are most common in the production of household appliances. This group includes alloy 08×17T, which is most often supplied to production in the form of rolled sheets.

Features of marking and GOSTs

Labeling of food grade stainless steel is carried out in accordance with the established rules in GOST. As a rule, when designating an alloy, the concentration of the main alloyed elements is indicated.

Download GOST 5632-2014

Among the marking features, we note the following points:

1. The first number indicates the concentration of carbon - the main element that determines the strength and hardness of the alloy.
2. Certain symbols are used to designate alloying elements. For each, the concentration is indicated as a percentage.
3. If a number is not placed in front of the symbol, then the concentration of the chemical element is less than one percent.

Food grade stainless steel in industry

In addition, food grade stainless steel (GOST defines sanitary and technical standards) may contain other impurities that are not indicated when labeling. An example is sulfur and phosphorus - both elements are included in the composition of almost all metals, they are harmful impurities, and with an increase in the amount of which the alloy loses its properties.

Source: https://moy-instrument.ru/masteru/kak-otlichit-pishhevuyu-nerzhavejku-ot-tehnicheskoj.html