How to determine the grade of steel: checking the type and composition of the metal

How is steel grade determined?

During the production cycle, everything is simple and clear - metal blanks are purchased in rods, bars, sheets or strips. On one of the edges they are marked (engraved with numbers and letters) and have a special color - color is also a signal for metallurgists. In production, the bulk of the metal is used first, and this marked tip is used at the very end. But at home, craftsmen often buy steel sheets by hand or in such a form that the markings cannot be recognized. Therefore, below we will give several elementary ways to determine the material. To do this you will need:

• the workpiece itself (it is advisable to place it in a vice to reduce the risk of injury);
• hammer and chisel;
• grinding wheel;
• file;
• bake.

Also, create optimal conditions for the test in advance, namely, good lighting, equipment (wear safety glasses, protect exposed areas of the body), materials for comparison, if needed, Internet access.

Now we list the possible verification options.

Methods for determining steel grade

1. Attach the cutting edge of the tool to the surface. Our task is to cut off the top thin layer of medium length. Now let's analyze the chips. If it breaks quickly, you can’t get it at all, only short fragments, then most likely you have a high-carbon one in your hands. It is because of the carbon content that plasticity is lost, hardness appears, and strength suffers. A low-carbon composition, on the contrary, will give long curls of a uniform structure. And the process of knocking down the top layer will be easier.
2. More energy-consuming method. Suitable for those who have a stove - the most ordinary wood stove will do. But for the purity of the experiment, the higher the temperature maintained inside (before hardening), the better. Take a metal rod and a file. We make an incision and remember what efforts were made. Now we subject the sample to hardening and re-cut. If after heating the ease of manipulation remains, then you are dealing with a low-carbon one. A large amount of carbon in the composition makes the metal difficult to process after hardening.
3. For the third method we will need a grinding wheel. First, prepare your workplace - good lighting, put a dark, uniform background behind it so that the sparks are better visible. These are the ones that will be used to check the steel. If they are large, splash in a large volume, and are bright, then you are dealing with high hardness of the material. Otherwise, with a small sheaf and small particles of sparks, the metal structure is not solid. To correctly interpret the result, take another workpiece for comparison, the brand of which you know. Be sure to press both samples with the same force and at the same angle.
4. Using a grinding wheel, you can determine the material by other characteristics, for example, the color of the sparks. Of course, a number of indicators are quite subjective; it is much better to test in comparison with other samples. If you have a lot of small stars scattering in different directions, but they fly close, and they have a red tint, then you are dealing with a high-carbon sample. A sheaf that is lighter and has fewer sparks will indicate an average carbon content, while a very small part of it in the composition will give long straw-colored stripes without stars at the ends - this is how iron is turned.

If you are dealing with steel that has been alloyed, then some of its characteristics can suggest what alloying elements were added. For example:

• The presence of phosphorus in large quantities (this is a harmful impurity) will lead to increased cold brittleness, that is, at negative temperatures, a metal sheet or rod will simply break and cracks will form on it.
• Chrome makes the workpiece very resistant to corrosion, so if you take a clean, rust-free sample that has been sitting outside for a long time, it is most likely chrome.
• The same chromium, like nickel, if a large amount is added, removes the magnetic properties of the sample.

Some other characteristics and special properties are not easy to check at home. But if you can determine the features of metalworking, hardening, and heat resistance, then you can find out the presence of other additives.

General concepts about brands

We will consider markings that were developed back in the USSR and are now actively used in Russia and in all neighboring countries. It is universal in that it includes all classes, of which there are a lot. Basic moments:

• The number is assigned to the entire batch, and a stamp is affixed (paint, by engraving) to each individual product. It consists of numbers and letters, no symbols.
• Sometimes the abbreviation “St” is indicated at the very beginning, that is, “steel,” but this is not at all necessary.
• Typically, the initial numbers indicate hundredths of carbon, while the letter designating this substance is not placed, since carbon content is one of the fundamental characteristics of alloys. For example, if 20 is indicated, then the content is 0.2%.

Now in more detail with an example:

We have letters (Russian or Latin, as in the sample), they indicate the alloying element that is in the composition. If you need a method for determining the grade of metal without reference books, then you will need to fill in the most common abbreviations:

• A – nitrogen.
• N – nickel.
• X – chrome.
• T – titanium.
• K – cobalt.
• B – tungsten.
• C – zirconium.
• C – silicon.
• D – copper.
• B – niobium.
• G – manganese.
• Yu – aluminum.

A more complete list can be found in regulatory documents. By the way, it is interesting that GOST standards for the production of steel alloys, adopted back in the Soviet Union, are still in force today, as are the marking rules. In total, the nomenclature includes more than 1,500 individual values ​​- this is the number of varieties of metals in this category that are manufactured all over the world. It is not surprising that in such a variety it is very difficult to determine by eye what kind of material is in your hands.

We figured out the letters, now the numbers. Everything is simple with them - the first one belongs to carbon, and then we read from left to right: a letter, and behind it a digital indication - what proportion (as a percentage) of the substance is in the composition.

But, in addition to the designation of chemical elements, you can also find other, sometimes incomprehensible, letters. They may indicate the presence of special properties, as well as membership in any category. Let's look at how to check the steel grade using these designations below.

Material quality

In addition to additives specially introduced in precise proportions that improve the quality of the alloy, there are harmful impurities - they are in the solution during smelting without the intention of the metallurgists. These are usually non-metals that have a negative effect. For example, phosphorus makes the metal very brittle when the temperature drops, and sulfur leads to the formation of cracks when heated. Therefore, they try to get rid of these and other elements (oxygen, excess nitrogen), and the less of them in the sample, the higher its quality. May be called:

• ordinary, then “St” is put at the very beginning, this means that the impurities are in the amount of 0.06-0.07%;
• qualitative - no special marks are placed, substance content - up to 0.035%;
• high quality - at the end of the marking there will be an “A” (not to be confused with nitrogen), this means that no more than 0.025% of harmful elements;
• especially high-quality - the name ends with the letter “Ш”, and the percentage does not exceed 0.02%.

In addition, when working with an ordinary quality class, it is also necessary to take into account the categories - from 0 to 6. This results in “St” with a digital index. The lower the number, the better the composition, in terms of impurities.

Another important concept is the degree of deoxidation. This is an indicator that reflects the behavior of the metal in the molten state. It depends on how oxygen is removed from solution. According to this classification, alloys can be:

• Calm (SP in the marking), they harden without gas evolution. They contain manganese, silicon or aluminum.
• Semiquiescent (SS), which are deoxidized in two stages due to the retained carbon.
• Boiling (KP). During their heating, carbon dioxide is actively produced, which rises to the surface in bubbles and thus solidifies.

And if you are dealing with alloy steel, you may come across specialized designations; for example, here are a few abbreviations:

• Ш – ball bearing purpose.
• R – high-speed cutting for making tools.
• A – automatic specialized.
• E - electrical, it is purified from virtually any impurities, more than 99% is solid iron.

General classification of steels

Steel is an alloy of iron and carbon (up to 2% carbon). According to the chemical composition, steel is divided into:

• carbon;
• alloyed;

According to quality, steel is divided into:

• ordinary quality steel;
• quality;
• improved quality;
• high quality

Carbon steel of ordinary quality is divided into three groups:

• A - supplied according to mechanical properties and used mainly when products made from it are subjected to hot processing (welding, forging, etc.), which can change the regulated mechanical properties (St0, St1, etc.);
• B - supplied by chemical composition and used for parts subjected to such processing in which the mechanical properties change, and their level, in addition to the processing conditions, is determined by the chemical composition (BSt0, BSt1, etc.);
• B - supplied according to mechanical properties and chemical composition for parts subject to welding (VSt1, VSt2, etc.).

Carbon steel of ordinary quality is produced in the following grades: St0, St1kp, St1ps, St1sp, St2kp, St2ps, St2sp, StZkp, StZps, StZsp, StZGps, StZGsp, St4kp, St4ps, St4sp, St5ps, St5sp, St5Gps, Stbps, Stbsp.

The letters St indicate “Steel”, the numbers are the conventional number of the brand depending on the chemical composition, the letters “kp”, “ps”, “sp” are the degree of deoxidation “kp” - boiling, “ps” - semi-calm, “sp” - calm ).

High-quality structural carbon steel by type of processing upon delivery is divided into:

• hot rolled and forged;
• calibrated;
• round with special surface finishing, silver.

Alloy steel is divided according to the degree of alloying:

• low alloy (alloying elements up to 2.5%);
• medium alloyed (from 2.5 to 10%);
• highly alloyed (from 10 to 50%).

Depending on the main alloying elements, steel is divided into 14 groups.

High alloys include:

• corrosion-resistant (stainless) steels and alloys that are resistant to electrochemical and chemical corrosion; intergranular corrosion, stress corrosion, etc.;
• heat-resistant (scale-resistant) steels and alloys that are resistant to chemical destruction in gas environments at temperatures above 50 °C, operating in an unloaded and lightly loaded state;
• heat-resistant steels and alloys that operate under load at high temperatures for a certain time and at the same time have sufficient heat resistance.

Depending on the chemical composition and properties, alloyed structural steel is divided into:

• quality;
• high quality A;
• especially high-quality Ш (electroslag remelting).

According to the types of processing upon delivery, steel is distinguished:

• hot rolled;
• forged;
• calibrated;
• silverfish

Rolled products are manufactured according to their intended purpose:

• for hot forming and cold drawing (rolling);
• for cold machining.

Spectral analysis of metals

This is a modern method that allows you to find out the structure of almost any mineral or finished product based on analyzed physical properties, in particular, reflection, emission, luminescence, etc. The fact is that atoms of different substances emit special wave elements characteristic only of one. They have their own length, frequency, etc. Therefore, only the wave nature of the sample can be taken into account in order to accurately determine what additives are in its composition. And for this they use a spectral determinant of steel grade. This is the device that performs this analysis. It is available in almost all industries, but can also be used in everyday life, since it does not require any special skills to use.

But there are nuances. For example, it is important to take into account the fact that during burning (as the sampling process is terminologically called), only the top layer of a few mm is determined, so it is very important that the entire bar (rod) is made of a homogeneous material. It is also worth knowing that there are four types of spectral analysis:

• Emissive – registers waves emitted by a substance.
• Absorption – takes into account how much it absorbs.
• Luminescent - determines whether additives can glow or emit light.
• Raman - focuses on the scattering of light and the excitation of molecular vibrations.

This method is very widely used in laboratories, as well as in large industries. The device uses a high-temperature spark or electric arc plasma (more than 10,000 K) as a light source, which is generated by an external storage device. Only after such excitation from the outside do atoms begin to emit their own waves, and conclusions can be drawn based on their length and features.

Brand of steels and alloys

Home/Brand of steels and alloys

Brand of steels and alloys

“In recent years, to improve the quality of steel, new methods of smelting have been used, which are

reflected in the designations of steel grades: "

VD - vacuum - arc;

VI - vacuum - induction;

Ш - slag;

PV - direct reduction;

ESR - electron slag remelting;

SD - vacuum-arc after slag remelting;

EBL - electron beam remelting;

PDP - plasma-arc remelting;

IS – vacuum-induction plus electroslag remelting;

IP - vacuum - induction plus plasma - arc remelting.

“In addition to those listed, the plant produces from experimental grades of steel having the following

designations:"

EP - Elektrostal (plant) search;

EI - Elektrostal Research;

ChS - Chelyabinsk steel;

ZI - Zlatoust Research;

VNS - VIEM stainless steel;

DI - Dneprospetsstal (plant) research.