Heat Resistant Steel Numbering System for European and International Standardising Organisations
Heat resistant steel is steel that has been alloyed to resist the damaging effects of heat, such as oxidation and corrosion. This type of steel is essential for engineering and fabrication projects that require resistance to extreme temperatures. Manufacturers of heat resistant steel create a variety of alloy compositions to produce different grades of the metal according to their own specifications. European and International Standardising Organisations (ESOs & ISOs) have developed their own numbering system for heat resistant steel in order to provide a uniform system for the identification of different grades of heat resistant steel across the European and global markets.
In order to understand the ESOs & ISOs numbering system, one must first become familiar with the basic components of heat-resistant steel. Heat-resistant steel is typically composed of carbon, manganese, chromium, silicon, molybdenum, nickel and vanadium, among other elements. These elements are added to the final formulation in varying amounts to produce different levels of mechanical and physical properties, such as increased strength and improved corrosion resistance.
The ESOs & ISOs use two numbers to identify different grades of heat-resistant steel. The first number (or prefix) is used to identify the series or type of alloy or alloy composition; for example, stainless steel is labelled ‘316’. The second number (or suffix) is used to identify the grade within that series. For example, 316L is a low-carbon grade of stainless steel.
In addition to the two-number system, the ESOs & ISOs have an alpha-numeric code which is based on the European standard EN 10088-3. This code is used to further classify heat-resistant steel grades, based on their properties. The code includes the series (prefix) and grade (suffix), as well as additional specifications such as hardness, corrosion resistance and temperature resistance.
For example, a 304L heat-resistant steel specification might read EN 10088-3:1.4306 X2CrNi19-11. The prefix in this code is ‘1.’, and the suffix is ‘X2CrNi19-11’. The first part of the suffix, ‘X2CrNi19’, describes the composition of the alloy; the ‘X2’ shows that the steel contains Chromium and Nickel, while the ‘CrNi19’ shows the relative percentages of each element. The last part of the suffix, ‘11’, is the grade number and is used to identify the specific grade of alloy within the series.
In addition to EN 10088-3, other standards may also be used to identify heat-resistant steel grades. Depending on the use and application of the steel, different standards are applicable, such as ASTM standards for aerospace alloys or DIN standards for automotive alloys. As with the EN 10088-3 codes, these other codes will typically include a prefix and suffix to identify the series and grade of the alloy respectively.
The ESOs & ISOs numbering system is an important tool that manufacturers and fabricators can use to properly identify and source the correct grade of heat-resistant steel for their application. The system enables them to easily differentiate between various alloys and grades, and source the right type of heat-resistant steel for the job. It is important for all those involved in projects that require heat-resistant steel to have a good understanding of the ESOs & ISOs numbering system in order to ensure that the correct grade and type of steel has been selected for the job.
