How to determine steel grade at home

All types of rolled metal are subject to marking, which contains information about the composition of the alloy, the content of additives, quality, and degree of deoxidation. If there is no such mark or an old metal structure is used, then the question arises of how to determine the grade of steel without laboratory testing. The grade of the alloy is determined by the qualitative and quantitative chemical composition and its hardness. If you know exactly these two indicators, you can accurately identify the metal.

The chemical composition shows the base metal, alloying and general characteristics. And hardness depends on production technology and additional processing.

In laboratory and production conditions, X-ray fluorescence spectrometry, large-metric titration, test cutting methods, and testing on an emery wheel are used. Some methods can be used for independent analysis.

How to determine steel grade at home - Metals, equipment, instructions

There are simply a huge number of different steel options, each grade is characterized by its own specific features.
If the manufacturer has not carried out markings, then you can find out the characteristics of the metal only by independently conducting various tests. We'll talk about this in more detail later. How to determine steel grade

Methods for determining steel grade

A fairly common question is how to determine the grade of steel. There are several common methods:

The first involves removing chips from the surface, for which a chisel can be used. At high carbon concentrations it will be short and brittle. A decrease in the indicator causes an increase in plasticity. However, it is not possible to accurately determine the brand using this method.
The second method involves hardening the product, after which it is necessary to make cuts. If the material is simply sawed before and after hardening, then it contains a small amount of carbon. Due to the increase in carbon concentration after treatment, the surface becomes too hard.
Determining the steel grade by spark is based on a visual inspection of the sparks that are formed when processing the surface with a grinding wheel. With an increase in the size of the sparks and their number, the hardness index increases, which depends directly on the carbon concentration. Such a test does not give an accurate result, since the main characteristics of the flying chips depend on the force of pressing and some other points. You can find tables that decipher the qualities of a material based on chips.

Spark test methodDevice for determining steel grade

You can also determine the brand by the color of the sparks produced. For this purpose, special tables were compiled. The test can be carried out at home only if the lighting is correct.

However, it is impossible to accurately identify the material in this way.

The option with alloying elements can also be identified by other performance characteristics, for example, resistance to high humidity or strong magnetism.

General concepts about steel grades

In the CIS, the applied designation standards are characterized by the fact that they can be used to indicate the main elements. When considering the issue of decoding the brand, we note the following points:

The abbreviation “St” is often used. In other cases, no abbreviations are used at all, only numbers.
In most cases, the first number indicates the carbon concentration. The following can be used to indicate the amount of alloying components.
The composition may include alloying components that significantly change the properties of the material. An example is the inclusion of chromium, which increases resistance to high humidity.

Classification of steels by purpose

Labeling is deciphered using tables that indicate the designation of the chemical element.

Marking of steels according to international and CIS standards

In order to decipher a brand, you can use a variety of standards. Some alloys are designated by certain symbols that indicate the purpose of the metal.

An example is the following points:

The letter “Ш” is used to designate metals that are used to make bearings. They are characterized by increased wear resistance.
High-quality alloyed workpieces are designated by the letter “L”. Often the symbol is indicated at the end.
“T” is used to designate heat-strengthened rolled products.
High corrosion resistance of the workpiece is determined by the letter “K”.
If copper is included in the composition, then the symbol “D” is used when indicating the brand.
Instrumental can be identified by the letter “U”. They are often used in the manufacture of various tools that are characterized by high wear resistance.
The symbol “P” is indicated to designate alloys that contain tungsten. Such a substance significantly increases the heat resistance of the structure.

By deciphering the brand, you can determine which chemical elements are included in the alloy. The numbers in most cases indicate the concentration, symbols, type of alloy and specific chemical elements.

European steel marking system Carbon steel grades according to GOST and ISO international standards

In conclusion, we note that there is simply a huge number of products on sale; in many cases, the brand is affixed by the manufacturer. It is almost impossible to independently determine the composition without the use of special equipment.

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Classification by production method

Much depends on the equipment used. Blast furnaces have long been replaced by more environmentally friendly and efficient options. Over the past century, several new technologies have emerged:

Converter or Bessemer. During the smelting process, compressed, oxygen-enriched air enters the converter, and the carbon component is burned off. Additional fuel is not required, so during the reaction additional energy is released and the mass heats up on its own. Before the invention of technology, it was impossible to obtain a melting point of 1600 Co, so only cast iron was produced at 1400 Co. In an improved form, the method is still used today.
Martenovskaya. The scientist proposed to reuse the resulting heat: the outgoing air heats the incoming air. For this purpose, the furnace was equipped with a regenerator, which not only restores heat, but also traps soot and condensate. The installations operate under thermal conditions not exceeding 2000 Co. The invention made it possible to remelt scrap; regenerators are used in modern installations, especially glassblowing and plasma.
Elektrostal is a new generation of equipment using induction and arc smelting. In modern installations, the most contaminant-free products are obtained; electricity costs are reduced, since precise temperatures are maintained. Heat-resistant and refractory materials are created in plasma-arc furnaces. It became possible to produce steel using the direct method, without melting the cast iron base.

The maximum increase in temperature to 20,000 Co made it possible to obtain iron reinforced with molybdenum and titanium. Together with melting technology, metal processing methods are simultaneously being developed: cutting, bending, rolling.

How to determine the composition of a metal?

Having selected used tools (needles, files, rasps, braids, etc.), first of all you should determine what grade of steel they are made of. To keep your search as limited as possible, you should know what types of steel a particular tool is made from.

Thus, files can be made of both tool carbon steel (U10, U11, U12, U13) and alloy steel (ShKh6, ShKh9, ShKh15). You can learn more about this from the list of tools below.

The files presented in the KovkaPRO assortment are made of high-alloy steel with a hardness of 64-66HRC

Products made of tool and alloy steel:

Files - U10, U11, U12, U13, ШХ6, ШХ9, ШХ15 Needles - U10, U11, U12 Rasps - U7, U7AShabers - U10, U12 Chisels, chisels - U7, U8 Taps - U10, U11, U12, P9, 9ХС, Р18 Wood drills - 9xsewrla for metal -r9, P18 Exverts-P9, P18, 9XS cutters-P9, P18 Zubila, screwdriver-U7A, U8A, 7XF, 8XFPROPERS-U8 Acernerers-U7A, 7XF, 8XFSHEVENENETEN NE7A, U8APILA-U8 Gapolotnita Rules-UN U8GA, U10 Hacksaw blades – U8, U8A, U9, U9A, U10, U10A, U11, U12 Metal shears – U12AMhammers and sledgehammers – U7, U8 Axes – U7 Scythes, sickles – U7, U8 Forks, teeth (peckers) – U7, U8 rakes

Blacksmith tools – U7, U8

Stage 2: determination of carbon content in steel

How can you determine specifically whether, for example, a file is made of carbon or alloy steel? To do this, you should resort to a simple old method. Craftsmen noticed that small metal shavings obtained when processing metal with an abrasive wheel, when heated, produce a sheaf of sparks, which have their own characteristic features for each metal.

The “straws” that make up a sheaf of sparks, each brand has its own special ones: long, short, continuous, intermittent, heaped and sparse, smooth or thickened; from each of them small bright stars can be separated, sometimes very abundantly; The brightness of the glow of the sheaf of sparks is taken into account, as well as color shades - from light yellow to dark red.

The higher the carbon content in the steel, the more bright stars there are in the sheaf of sparks. If the steel contains a little carbon, for example about 0.12%, then the sparks coming out from under the abrasive disk will fan out in the form of slightly curved lines of yellow-straw color, with thickenings in the middle and at the end (1, see Fig. on page 105).

Steel containing 0.5% carbon and having an average hardness produces approximately the same sparks, but a small number of stars separate from the place of average thickening (2). Copious sparks with stars (3) are released from the high-carbon tool steel.

Chromium steel has long, orange-red sparks; from them, like thin branches from the main branch, short sparks with stars at the end extend from them at different angles (4). Tungsten steel sparks intermittently, and also has small thickenings at the end (5).

Chrome-tungsten high-speed steel produces both short and long sparks of a dark red color with thickenings at the end (6).

Stage 3: Tool Test

Now let's get back to the file. Before you start testing it, you must wear safety glasses and place a sheet of black-painted plywood near the sanding wheel. On a black background, the sparkling metal is visible much more clearly, and the eyes have to strain less.

If we forcefully run a file over the emery wheel and get abundant sparks of a bright yellow color with many stars separating from them, we can conclude that it is made of high-carbon tool steel (U10-U13).

Conversely, a sheaf of orange-red long sparks with branches and stars at the end indicates that the file is made of alloy steel (ШХ6, ШХ9, ШХ15). Of course, in this way only the approximate chemical composition of steel is determined, but for amateur practice this is quite enough.

Knowing that the file is made of tool steel of the indicated grades, the heat treatment mode is determined from the table.

The table shows that the U11-U13 steel from which the file is made is annealed at a temperature of 750°C and then gradually cooled in air. Annealing is carried out in a muffle furnace, forge or in the firebox of a conventional furnace.

It is convenient to anneal metal objects in an electric school muffle furnace, since the built-in thermometer makes it possible to monitor the heating temperature. But the depth of the muffle furnace is limited.

If the file does not fit into it, it is wrapped in several layers of tarpaulin and broken with a strong blow of a hammer.

The broken file is removed from the tarpaulin, annealed in a muffle furnace, and then slowly cooled. The resulting scale often interferes with machining. Therefore, wearing glasses and mittens, they knock it down with a hammer and a chisel.

Annealed and processed tool steel becomes quite soft: it can be easily filed, sawn and forged. With minimal hardness, it has maximum plasticity and viscosity. This makes it possible to make from it gravers for engraving, embossing, chisels, cutters, punches, and other tools for the artistic processing of metal.

Having made the desired tool from a file, it is hardened by heating according to the table to 780°C, followed by cooling in water.

After hardening, the steel becomes brittle, so it is tempered: heated to 180°C and cooled in water or machine oil.

When tempering, the heating temperature of the metal is controlled by the so-called tarnish colors, which correspond to a certain heating temperature.

Determination by hardness

Manufacturers often use softer alloys to reduce the cost of products, such as cutlery. If it is not possible to order a laboratory analysis, you can use the following methods:

Use a hardness tester - stationary or mobile. It shows a fairly accurate result in Rockwell units.
Use a file or needle file. A high-quality tool is accompanied by documentation indicating its hardness. To check, a metal object must be secured in a vice and a file passed over it with medium pressure. If a mark remains, it means that it has less hardness than the tool.
Impact with a reference sample of an alloy whose hardness is known. The part to be tested is fixed and a point blow is applied to it. If a dent forms on it, it means it is softer than the sample. If the impact mark remains on the standard, it means it is harder.
Remove the shavings from the nail. Used to test a sharp object, such as a knife. Nail 100 is hammered halfway into a hard board using a knife and trying to remove shavings from it. If this works, then the hardness of the material is 50 units. The softer alloy is deformed from this action.

The above methods can be applied at home, but laboratory tests give the most accurate results. They are held in Krasnodar.

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, 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.

Designation of products with alloying parts

In order for the marking of steels 10 and 20 to fully demonstrate their technical characteristics, letter marking is used for alloying additives. As a rule, Russian letters correspond to the names of elements. However, there are exceptions, since there are nuances in which the beginning is observed with one letter. For better understanding, the following table has been developed:

Designation	Chem. element	Name	Designation	Chem. element	Name
X	Cr	Chromium	A	N	Nitrogen
WITH	Si	Silicon	N	Ni	Nickel
T	Ti	Titanium	TO	Co	Cobalt
D	Cu	Copper	M	Mo	Molybdenum
IN	Wo	Tungsten	B	Nb	Niobium
G	Mn	Manganese	E	Se	Selenium
F	W	Vanadium	C	Zn	Zirconium
R	B	Bor	YU	Al	Aluminum

There are only 2 non-metals in it - silicon and nitrogen, and carbon is absent. There is carbon impurity in any steel variety, so the designation is only necessary for its content.

How to determine steel grade at home

Steel grade definitions

High-precision methods for determining the grade of steel and alloys

To accurately determine the alloy grade, two important components are necessary:

qualitative and quantitative chemical composition glory;
alloy hardness.

Having such data, you can determine the grade of almost any alloy, since the classification of alloys is based on them.

So the chemical composition of the alloy allows you to determine the base metal, the degree of alloying and the general properties of the alloy.

And the hardness of the alloy makes it possible to distinguish between alloys of the same chemical composition, but with different additional processing of the metal or with different smelting techniques.

Since alloys with the same chemical composition and different properties are extremely rare, in most cases an accurate determination of the alloy composition is sufficient.

Determining the chemical composition of an alloy consists of determining the base metal and determining alloying additives (metallic and non-metallic in nature).

The most accurate and fastest method for determining the content of base metal and alloying components of a metallic nature in an alloy is X-ray fluorescence analysis (X-ray fluorescence spectrometry, XRF, XRF, RFSA). In addition, the advantages of this method include indestructibility and the ability to analyze extremely small samples.

The XRF method makes it possible to identify and determine the content of elements from Cl (17) to U (92) in alloys.

To determine the content of elements such as Li, Be, B, N, O, F, Na, Mg, Al, Si, P, S in alloys, the XRF method in an inert gas environment is used.

The determination of C content in alloys is carried out by automatic coulometric titration based on pH value.

Inaccurate (approximate) methods for determining the grade of steel and alloys

If the grade of steel is unknown, you can approximately determine the quality of the steel by fracture and by test cuts.

The crystalline structure at the fracture site of the steel can be used to judge its strength: the thinner the crystalline structure, the higher quality the steel.

During test cuts, low-hardness steel is filed with any file (including a garnish file), medium-hard steel with a personal and velvet file, and high-hardness steel with only a velvet file.

You can more accurately determine the grade of steel by the resulting beam of sparks on the emery wheel. The shape and length of the spark threads, the color of the sparks and the number, width of the spark beam are different for different grades of steel. By testing standard steel samples for spark, you can learn to recognize steel grades.

Below is a description of the shape of spark beams for some steel grades:

low-carbon steel - uniform, continuous straw-yellow threads of sparks with a small number of stars;
carbon steel with a carbon content of about 0.5% - a bunch of light yellow threads of sparks with stars at the end;
tool steel U7-U10 - a diverging bunch of light yellow threads of sparks with an increased number of stars at the end;
tool steel U12, U13 - a dense and short bunch of light threads of sparks with a very large number of stars at the ends of the threads, while the stars are more branched;
steel containing chromium - a dense bunch of dark red threads of sparks with a large number of yellow stars at the ends of the threads, the stars are highly branched;
high-speed steel containing chromium and tungsten - a bunch of intermittent dark red threads of sparks, at the ends of which there are lighter drop-shaped stars;
spring steel containing silicon - a wide bunch of dark yellow threads of sparks, at the ends of which small stars of a lighter color are formed;
high-speed steel with a cobalt additive - a wide bunch of dark yellow threads of sparks without stars at the end.

Without issuing a protocol with a stamp - 650 UAH/request, if everything is official - 2000 UAH.

Determination of carbon content in alloys

Carbon analysis methods (determination of carbon content in alloys)

Carbon in steels and alloys is analyzed by various methods: an OES100 spark optical emission spectrometer or the combustion method with an infrared analyzer. Carbon can also be analyzed by X-ray fluorescence spectrometer, laser optical emission spectrometer and other methods.

Carbon analyzer AN-7529

Express carbon analyzer AN-7529 is designed to determine the mass fraction of carbon in steels and alloys using the method of automatic coulometric titration based on pH value, for marking analyzes of carbon in products and raw materials of metallurgical and metalworking enterprises.

The AN-7529 express carbon analyzer is used to carry out analyzes in the laboratories of enterprises and research institutions in various industries.

The analyzers are designed for continuous round-the-clock operation in factory laboratories at ambient temperatures from 10 to 35C, relative humidity up to 80% and meet the requirements for group 2 devices.

Measurement characteristics

Measured carbon concentration ranges: 0.03-9.999%

Certification

Without issuing a protocol with a seal – 950 UAH/issue, official conclusion from – 2600 UAH.

If you need to determine the steel grade, please contact Us

Tests for determining the grade of stainless steels

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.

Instruments for determining steel grade

A device for determining steel grade is indispensable where it is necessary to carry out highly specialized express analysis in the field: in workshops and warehouses, in laboratories and in open areas. Such a device will be useful for enterprises that work exclusively with steels and do not need detailed chemical analysis of other alloys.

Specialists of JSC "Spectral Laboratory" have developed and produce several original portable models for identifying steel grades. Thanks to these simple and convenient indicators, you can solve a number of critical production problems.

They make it possible to confirm the compliance of the metal of parts with that specified in the design documentation during incoming inspection, to avoid errors when issuing blanks for production, and to analyze ready-made designs of both large-sized and very small parts.

Operating principle of the devices

To find out the brand of the metal being tested, it is enough to measure its thermoelectromotive force, which directly depends on the chemical composition, and compare it with similar parameters of the reference sample. At the same time, it is not necessary to acquire a bulky collection of templates for all well-known steel grades. It is enough to know the standard values of their thermo-EMF and enter them in comparative tables.

Main characteristics of devices

An important advantage of the devices is that a very small area is sufficient to carry out the test, exactly the size on which the electrodes will fit.

The surface to be analyzed must first be cleaned of paint, oils, rust, and galvanic coating. The measurement procedure and operating instructions are included in the passport of each analyzer.

The devices operate at low voltages.

Advantages of our equipment for determining steel grades:

high accuracy of the results obtained;
ease of use;
reliability;
compactness;
speed of measurements;
relatively low cost.

Our products are an excellent alternative to both traditional empirical methods (which give very approximate results) and expensive spectrometers.

It is not surprising that these devices have found such widespread application.

How to determine the category of scrap metal?

Payment for an unsorted batch of scrap metal is usually set by the receiver at the level of the cheapest grade.

Naturally, the maximum benefit from the delivery of recycled ferrous metal can be obtained by first preparing the scrap according to the established categories.

The main types of ferrous metal waste are determined by GOST 2787-75 and are slightly modified at collection points, for example, for railway or automobile scrap.

Principles for constructing categories

The classification of recycled ferrous metals is carried out in accordance with GOST, based on the following characteristics of scrap metal: carbon content, quality grade of recyclable materials and the presence of alloying additives, their type, concentration. Since the most popular scrap metal is unalloyed iron, the category of waste is determined by two parameters: the type of iron and the quality (final form) of the scrap.

Quality classification

The fewer harmful inclusions remain, the higher the quality characteristics, but sometimes this is not economically justified. The standardization system provides for three classes.

High quality

This category includes carbon products. They contain the most phosphorus, sulfur and gases; they are not homogeneous enough. The qualities are satisfactory for the production of structures and parts.

Unalloyed quality steels are designated by the letter K. For example, 20K

High quality

The low content of harmful impurities and non-metallic inclusions is indicated in the labeling by the letter A at the end. Of the U8 and U8A brands, the second will have the best characteristics, the products will be more accurate and of higher quality.

The letter A is written at the beginning in grades of highly machinable structural steels (A12-automatic, A30, A40), but in this case it does not reflect compliance with the cleanliness standard.

Particularly high quality

Alloys with the minimum possible amount of impurities are designated by the method of production at the end of the marking:

VD – vacuum arc remelting;
Ш – electroslag remelting;
VI – vacuum induction;
PD – plasma-arc.

Special quality is achieved by alloying, since the base obtained from molten cast iron cannot be brought to such indicators. The sulfur content is reduced to 0.1%, phosphorus – to 0.025%. Examples: 30ХГСН2МА – VD. Numbers are omitted here, since additive concentrations range from 0.8 to 1.2%, so their share is rounded to 1.

How to identify stainless steel: methods and materials

Stainless steel is the name of a group of iron alloys that contain corrosion-resistant metals. Carbon, titanium, copper are used as additives, and the composition also includes from 12 to 25% chromium and nickel. Alloy steel alloys are not susceptible to corrosion and are resistant to moisture, aggressive environments, alkalis and acids.

Stainless steel is used to produce dishes, knives, elements of machine tools, cars and industrial equipment, especially in the chemical and oil industries. Such scrap is accepted at a high price, which depends on the composition. The most expensive alloys are those with a high nickel content (from 10%). To get maximum profit from scrap metal, it is important to know how to identify stainless steel?

Metals and alloys that are often confused

The silver alloy of iron and chromium is suitable for the production of kitchen utensils, medical instruments, bearings, cutting elements, etc. But these items are also made from the following materials:

nickel-plated brass (a white copper alloy with a zinc content of more than 25%);
cupronickel (silver-white metal made from an alloy of copper and nickel);
white copper (an alloy containing at least 25% nickel).

Polished aluminum, nichrome, nickel silver and other alloys used for the production of cookware, knives, and jewelry can easily be confused with alloy steel.

Despite their similar composition and high nickel content, they are easily distinguished at a scrap metal collection point and will not be accepted at the desired price.

There are several ways to determine whether aluminum or stainless steel has fallen into your hands: chemical, mechanical, etc.

Analysis using a magnet

In the laboratories of large collection points, a spectrometer is installed - an optical device for spectroscopic research. It is equipped with an interferometer to evaluate the intensity of spectral lines and measure wavelengths. The received data is processed by a computer, giving an accurate conclusion about the composition of the alloy.

If you need to identify stainless steel at home, use improvised but relatively reliable means. One of them is a magnet: it is generally accepted that stainless steel is not magnetic. However, this diagnostic method is not accurate enough, because martensitic and ferritic alloys have magnetic properties.

Using a magnet, only austenitic and austenitic-ferritic alloys with a high content of chromium and nickel can be detected. They are used to produce dishes, plumbing and refrigeration equipment, containers for food liquids, etc. Contrary to popular belief, it is impossible to accurately determine stainless steel with a magnet, but you can roughly identify its type.

Defining food grade stainless steel

As stated above, a magnet helps to identify food grade stainless steel at home. Alloys with a low carbon content and a large amount of nickel in the composition do not react to contact with it. Stainless steel with a high carbon content (more than 0.9%) has magnetic properties and is prohibited for use in the food industry.

Also, to determine food grade stainless steel, various acids are used (citric, tartaric, acetic, etc.). Alloys for food applications contain more alloying additives, so their surface film is stronger and contains almost no iron.

For additional protection against corrosion, passivation is used - a method of treating the surface of a metal, as a result of which its activity is reduced and it does not enter into oxidative reactions.

Under the influence of these acids, stainless steel may become covered with a light patina, which indicates its non-food purpose.

Types and grades of non-magnetic steels

If the origin of the product is known, the reaction with a magnet can roughly determine the type of stainless steel. The following brands are not magnetic:

AISI 409 (analogue 08X13) - containers for cargo transportation, parts for the exhaust system of a car, etc. are made from this ferritic steel. (plasticity and lack of magnetic properties are due to the extremely low C content - less than 0.03%);
AISI 304 (analogous to 8-12X18H10) - household items are made from it, as well as utensils and equipment for the food and pharmaceutical industries;
12Х21НБТ (ЭИ8П) – austenitic-ferritic steel for use in medium-aggressive environments, from which containers and equipment for the chemical and pharmaceutical industries are produced.

Stainless steel grades AISI 402–420, which contain from 11 to 14% chromium and less than 0.07% carbon, are not magnetic.

Magnetic stainless steel

AISI 430 steel (analogous to 08X17, which contains 15% chromium) has magnetic properties.

It is used to produce wire mesh, pipes for transporting petroleum products, and elements of gas and oil refining process plants.

Steel grade AISI 630 contains up to 5% nickel and chromium, as well as a large number of additives: copper, titanium, molybdenum. It is used in instrument making and metallurgy.

Stainless steel can be identified even if it is magnetic. To do this, place a sample of the material in 2% vinegar or another aggressive medium for 1–2 days. Corrosion-resistant alloys will pass this test without visible changes, but metals that are susceptible to corrosion will darken.

Copper sulfate will also help determine magnetic stainless steel at home. First clean the metal surface with sandpaper, and then apply a few drops of a concentrated substance (rusting alloys are covered with a red film).

Spark test

Testing metal for spark color is a common method of sorting scrap metal, which is used even by specialists. The grade of stainless steel can be determined by the following factors:

the number of sparks and flashes, which is directly proportional to the volume of carbon in the alloy;
the color of the sparks, which indicates the composition of the metal (the lighter it is, the higher the likelihood that this is low-carbon steel);
the presence of shiny white sparks, which indicates a high titanium content in the composition.

To carry out the test, an angle grinder (grinder) is required. Start grinding the surface of the steel and observe the reaction. The color, length and shape of the sparks will help you accurately determine metal or stainless steel.

"Yellow flow" or "white fork"

There are many types of sparks: “fork”, “twig”, “arrow”, etc. You learn to distinguish them with experience, but even an untrained person will be able to distinguish a dense and short stream of flashes from the long and rare sparks characteristic of stainless steel. The presence of dark red sparks coming out from under the grinding wheel indicates a high content of nickel, tungsten carbide and cobalt.

If a medium-density stream appears during the grinding process, and the sparks are straw-yellow at the base and white at the end, you have stainless steel.

A long stream of sparks, reaching 1.5 meters, indicates the presence of nitrogen in the composition.

In this case, it is not difficult to determine the grade of stainless steel: nitrogen alloys are quite rare and there are only a few of them (Nitrobe 77, Sandvik™ 14C28N, Böhler N680, etc.).

What does the price depend on?

Low-carbon, corrosion-resistant alloys are used to produce a wide variety of products: blades, profiled sheets, roofing materials, medical supplies. Scrap stainless steel can be collected when dismantling an old fence, dismantling an old refrigerator, throwing away unnecessary kitchen utensils, etc. In this case, potential income will depend on the following factors:

type of steel (austenitic, ferritic, martensitic, etc.);
steel grade (AISI 304, AISI 630, 12Х21НБТ);
type of rolled metal (sheet, section, pipe);
sheet thickness;
compound;
quality.

You can determine the stainless steel brand and composition in a laboratory setting by contacting a reliable collection point. We have the necessary equipment to analyze the composition, assess the quality and test the radiation activity of non-ferrous scrap. But you can pre-evaluate scrap metal at home.

How to evaluate quality?

The quality of stainless steel depends on various factors - from the amount of additives to the joining method. In places where welds are formed, the anti-corrosion properties of the metal deteriorate significantly, which over time leads to the appearance of rust and gradual destruction of the material.

Painted profiled sheets will have to be cleaned of the coating and sanded, damaging the protective layer on the surface. Accordingly, the metal will become less resistant to moisture, its quality will deteriorate, and therefore the price of such scrap will be lower. You can preliminary evaluate the properties of steel using a salt solution.

It should not leave stains on the surface of high-alloy steel. And water will leave yellowish stains on low-quality stainless steel.

The most expensive types of stainless steel

The cost is affected by the amount of nickel in the alloy: in the cheapest types its content does not exceed 5%. The most expensive are high-alloy alloys containing nickel from 12%.

The expensive scrap includes plumbing fittings and rings, wire and various electrical connectors (connectors, adapters, etc.).

Matte (a by-product of non-ferrous metallurgy) with a nickel content of over 35% is also highly valued, although it is classified as slag.

But the most common steel grade is A2, containing approximately 10% nickel and 18% chromium. It is usually used to make household items. To find out the exact price, visit our collection point: to evaluate scrap, specialists must inspect the metal, assess the degree of contamination, composition and properties.

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How can you determine the grade and properties of metals in the workplace?

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Metalwork and tool work

How can you determine the grade and properties of metals in the workplace?

Data about the actual chemical composition of the metal from which the part is made, about its actual hardness and strength, about the quality and nature of the heat treatment performed sometimes does not reach the mechanic’s workplace.

However, their knowledge is necessary, and a qualified mechanic can obtain the necessary data with sufficient accuracy for production needs, without resorting to the help of a workshop or factory metallurgy laboratory. In fact, the steel grade can be determined quite accurately by the color and nature of the flying sparks during grinding.

Carbon steels produce light yellow spark trajectories with individual sparkling stars, and the higher the carbon content in the steel, the more sparkling stars and the shorter the luminous spark trajectories. Steels alloyed with tungsten are distinguished by the red color of the spark beam: the more tungsten in the steel, the darker and redder the spark beam.

The sparkling stars characteristic of carbon steels turn into red drops in this case. Other alloying elements also change the nature of the spark. If, during a spark test, you use samples made of steel of certain grades and compare the nature of their spark beam with the nature of the sparks of the part being tested, then you can establish with sufficient confidence the grade of its steel.