Steel grades to classify various steels by their composition and physical properties have been developed by a number of Standards_organizations" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial" title="Standards organizations">standards organizations.

• steel_grades" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial" title="SAE steel grades">SAE steel grades
• Standards" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial" title="British Standards">British Standards
• Standardization" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial" title="International Organization for Standardization">International Organization for Standardization ISO/TS 4949:2003
• Standardization" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial" title="European Committee for Standardization">European standards - EN 10027
• For alloys in general (including steel), unified numbering system (UNS) of ASTM International and the Society of Automotive Engineers (SAE).
• Japanese steel grades : JIS standard
• Germany steel grades : DIN standard
• China steel grades : GB standard

[edit]steel_grades">European standard steel grades

steelgrade-diagram.svg" style="background-image: none; color: rgb(6,69,173); text-decoration: none; background-origin: initial; background-clip: initial">steelgrade-diagram.svg/220px-EN10027-steelgrade-diagram.svg.png" style="border-bottom: rgb(204,204,204) 1px solid; border-left: rgb(204,204,204) 1px solid; background-color: rgb(255,255,255); vertical-align: middle; border-top: rgb(204,204,204) 1px solid; border-right: rgb(204,204,204) 1px solid" width="220" />

steelgrade-diagram.svg" style="background-image: none !important; border-bottom-style: none !important; border-right-style: none !important; display: block; border-top-style: none !important; color: rgb(6,69,173); border-left-style: none !important; text-decoration: none; background-origin: initial; background-clip: initial" title="Enlarge">

EN 10027-1 steel grade designation system.

^[1] European standard steel grade names fall into two categories:

1. Steel specified by purpose of use and mechanical properties.
2. Steel specified by chemical composition.

The inclusion of a letter 'G' before the code indicates the steel is specified in the form of a casting.

[edit]Category 1

Basic steel grade designations for category 1 steels consist of a single letter (designating application) then a number signifying the mechanical property (often yield strength) dictated in the standard for that application designation. For some application designations another letter is included before the property value, this number is used to indicate any special requirements or conditions. These additional letters and values depend entirely on the application of the steel and are specified in the standard and far too numerous to mention here.

Below is a table indicating the most common application codes.

[edit]Category 2

These steel grades often begin with a letter (absence of a letter indicates non-steel/" target="_blank" class="keylink">alloy steel with Mn >1% or steel/" target="_blank" class="keylink">alloy steel with all alloying elements <5% by weight). The most common of these letters are C (Carbon) and X (Alloying element >5% is present). Subsequent to this letter is the carbon quantity by weight given as the percentage multiplied by 100. Following on from this are the alloying elements in order of decreasing weight percentage. Finally there is a series of numbers. Unless the type code is X or HS these numbers correspond (in the order respective to the alloying elements given earlier) to the value of the aforementioned alloying element multiplied by that element's adjustment factor (given in the standard). If an alloying element is present without an adjustment factor then that element's quantity is unknown or unimportant but is mentioned because it is added on purpose to the alloy. E.g. 13MnNi6-3 (0.13% Carbon, 1.5% Manganese, 0.75% Nickel)

If the type code is X, the numbers following the alloying elements are the actual percentage by weight of the corresponding alloying element.

In the case of High speed steels the code differs. Beginning with the letter HS signifying the type then the addition of four or less numbers signifying the percentages of the following alloying elements in order: Tungsten, Molybdenum, Vanadium, Cobalt. E.g. HS2-9-1-8 (2% Tungsten, 9% Molybdenum, 1% Vanadium, 8% Cobalt).

[edit]Additional symbols

In addition to the above category codes there are symbols that can be added to the grade code to identify any additional compositional requirements, delivery conditions, mechanical properties, &c. These values depend solely on the type/application code given in the first part of the code and are so numerous as to be impossible to indicate here. Additional symbols are separated from the main code by the plus sign (+).

The most common additional symbols are the impact and temperature codes for structural steels, category 1 - Sxxx.

Delivery condition codes are also relatively common, the most common being:

[edit]steel_number">European standard steel number

In addition to the descriptive steel grade naming system indicated above, within EN 10027-2 is defined a system for creating unique steel grade numbers. While less descriptive and intuitive than the grand names they are easier to tabulate and use in data processing applications.

The number is in the following format: x.yyzz(zz)
Where x is the material type (only 1 is specified so far), yy is the steel group number (specified in EN10027-2) and zz(zz) is a sequential number designated by the certifying body, the number in brackets being unused but reserved for later use.

The steel groups are indicated below:

The current certification body is the VDEh in Düsseldorf, Germany.

[edit]Comparison

Below is a table comparing steel grades from different grading systems.