When, speaking about the personal qualities of a person, they use the epithet “steel”, they mean an unbending character, a strong will or grip that is so simple not to defeat. Steel was invented to make durable and reliable mechanisms, tools, and weapons. Now you can not do without this metal.
What is steel, and how does it differ from iron? The main difference in impurities, the main of which is carbon. In order to give special properties to this metal, other components are added to the alloy.
The same steel grades in different countries are designated differently. Unfortunately, a common denominator has not yet been reached on such an important issue.
Throughout the territory of the former Soviet Union, with the exception of perhaps the Baltic countries, alphanumeric codes are used in accordance with previous state standards. Such a definition of the steel grade is very convenient and understandable, the number means the percentage of impurity content, and the letter means a chemical element.
Marks have become simple, in which only iron and carbon are present, are called structural. They are simply indicated, Art. 2, for example. This means that the carbon in it is 0.2%.
High-quality unalloyed steel has a similar coding, but the percentage of carbon is reflected in two digital characters, for example, Art. 08.
If the metal is intended for the production of vessels that have to work under high pressure, then the requirements for it are special. As in the case of structural high-quality steel, the percentage is expressed as a two-digit number, but the letter “K” is added at the end (example - Art.12K).
More complex metallurgical compositions are divided into groups - instrumental, construction, stainless and so on. Each of them has its own marking features, but the letter designation of alloying elements such as nickel (H), chromium (X), copper (D), tungsten (B), manganese (G), molybdenum (M), silicon ( C) cobalt (K).
The deoxidation method is also reflected in the coding of the steel grade. So, “calm” is indicated by the letters SP, “half-calm” - PS, and “boiling” - KP.
Alloy steel grades have a longer designation, which includes both letters and numbers. It should be remembered that when the impurity content is less than one and a half percent, the figure is not set. So, code 10 X2 M-W will mean that steel contains 0.1% carbon, 0.2% chromium and less than 1.5% molybdenum. There is also the letter "Sh", it indicates a reduced phosphate content. If “A” stood in her place, then this would concern sulfur. Such brands speak of additional quality characteristics.
Structural cast steel is indicated at the end by the letter “L”.
For building structures, a metal with a low yield strength is required, it is reflected by the letter “C” standing in front. The letter, standing at the back, speaks of additional properties (T - heat strengthening, K - corrosion resistance).
The determination of the grade of steel suitable for the manufacture of tools is made by the letter “U”, after which a double-digit figure of the percentage of carbon, for example, U8, is put.
There are also
stainless steels. Stamps, like 08X18H10T, look like a complex cipher, in fact, the same principle applies here as for alloy structural alloys. This does not apply to special cases when letters are assigned in honor of plants that first smelted metal with special properties.