How to read steel grades

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

When, speaking about the personal qualities of a person, they use the epithet "steel", they mean an inflexible character, a strong will or a grip that cannot be defeated so easily. Steel was invented to make durable and reliable mechanisms, tools, weapons. Now this metal is indispensable.

What is steel, and how does it differ from iron? The main difference is 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 are designated differently in different countries. Unfortunately, we have not yet come to a common denominator on such an important issue.

Throughout the territory of the former Soviet Union, with the possible exception of the B altic countries, alphanumeric codes are used in accordance with the previous GOSTs. This definition of the steel grade is very convenient and understandable, the number means the percentage of impurities, and the letter means the chemical element.

Steel grades simple, which contain only iron and carbon, are called structural. They are designated simply, Art. 2, for example. This means that it has 0.2% carbon.

Quality unalloyed steelhas a similar encoding, but the percentage of carbon is reflected in two digits, for example Art.08.

If the metal is intended for the production of vessels that will work under high pressure, then the requirements for it are special. As in the case of structural quality steel, the percentage is expressed in two digits, but the letter “K” is added at the end (example - St.12K).

More complex metallurgical compositions are divided into groups - tool, construction, stainless and so on. Each of them has its own marking features, but the general is the letter designation of alloying elements, such as nickel (H), chromium (X), copper (D), tungsten (B), manganese (G), molybdenum (M), silicon (C), cob alt (K).

The method of deoxidation is also reflected in the coding of the steel grade. So, "calm" is denoted by the letters SP, "semi-calm" - PS, and "boiling" - KP.

Alloyed steel grades have a longer designation that includes both letters and numbers. At the same time, it should be remembered that when the impurity content is less than one and a half percent, the figure is not put. So, the code 10 X2 M-Sh will mean that the steel contains 0.1% carbon, 0.2% chromium and less than 1.5% molybdenum. There is also the letter "Sh", it indicates a low content of phosphate. If instead of it there was "A", then this would concern sulfur. Such brands speak of additional quality characteristics.

Structural cast steel is denoted by the letter "L" at the end.

Building structures require low limit metalfluidity, it is reflected by the letter "C", standing in front. The letter on the back indicates additional properties (T for heat strengthening, K for corrosion resistance).

Determination of the grade of steel suitable for the production of tools is made by the letter "U", followed by a two-digit percentage of carbon, for example U8.

There are also stainless steels. Grades like 08X18H10T look like a complex cipher, but in fact, the same principle applies here as for alloyed structural alloys. This does not apply to special cases when letters are assigned in honor of the plants that first smelted metal with special properties.