Understanding the Copper Alloy BS EN Material Designation System

The copper alloy BS EN designation system (providing individual copper and copper alloy identifications) covers two parts: a symbol and a number. As with many other existing European national standards (ENs), symbols are based on the ISO compositional system (e.g. CuZn37 is 63/37 brass). ISO and EN symbols may be identical but the detailed compositional limits are not always identical and cannot be assumed to refer to unique materials.

Numbering System
A numbering system has been developed to offer a more user- and computer-friendly alternative. The system is a 6-character, alpha-numeric series, beginning C for copper based material; the second letter indicates the product form as follows:

• B – Materials in ingot form for re-melting to produce cast products
• C – Materials in the form of cast products
• F – Filler materials for brazing and welding M – Master alloys
• R – Refined unwrought copper
• S – Materials in the form of scrap
• W – Materials in the form of wrought products
• X – Non-standardised materials

A three-digit number series in the 3rd, 4th and 5th places is used to designate each material and can range from 001 to 999. Numbers are allocated in preferred groups, each series being shown below. The sixth character, a letter, indicates the copper or alloy grouping as follows:

Symbol Designations

Here are the key points about symbol designations:

• The symbols used are based on the ISO designation system (ISO 1191 Pt1).
• The principal element, copper, is first.
• Other alloying elements are included in decreasing order of percentage content.
• Where contents are similar, alphabetical order may be used.
• The numbers after elements represent nominal compositions.
• No number is normally used if the nominal composition is less than 1%.

Material Condition (Temper) Designations

Material condition (alternative term – temper) designations are defined in BS EN 1173. In most product standards, materials are available in a choice of material conditions. Depending on the product standard there may be one or more mandatory properties associated with the particular material condition.

For designation purposes the principal mandatory property for each material condition is identified by a letter, as follows:

A – Elongation
B – Spring bending limit
D – As drawn, without specified mechanical properties
G – Grain size
H – Hardness (Brinell or Vickers)
M – As manufactured, without specified mechanical properties
R – Tensile strength
Y – 0.2% proof strength

Products can only be ordered to one material condition and not a combination. However, besides the designating property, other properties may be mandatory; check the standard document for full details.

Normally three digits, but in a few instances four digits, follow the material condition designating letter, where appropriate, to indicate the value of the mandatory property with the possibility of a final character, ‘S’, for the stress relieved condition. Normally the value refers to a minimum for the property. Sometimes, as with grain size, it refers to a nominal mid-range value.

Castings
For castings, properties are dependent on the casting process used. This is designated according to the system:

GS sand casting
GM permanent mould casting
GZ centrifugal casting
GC continuous casting
GP pressure diecasting

Examples

CW614N – R420

Refers to wrought CuZn39Pb3 copper-zinc-lead alloy to be supplied to a minimum tensile strength of 420 N/mm²

CC750S-GS
Refers to sand cast CuZn33Pb2 copper-zinc duplex alloy

Ordering Information
Each product standard gives examples of the full ordering information required including quantity, product form, standard number, designation, condition, tolerances and packaging.

For drinking water applications, include ‘—DW’ after the material designation to ensure compliance in respect of the chemical composition according to the 4MS Initiative (see Part B – 4MS Common Composition List for approved copper alloys).

Declarations of Conformity
Where the full quality systems standardised in EN ISO 9001 series of standards are not required, a declaration of conformity may still be needed to confirm compliance with order requirements:

In EN 1655 ‘Copper and Copper Alloys – Declarations of Conformity’, four levels of declaration of conformity are available:

Type A for suppliers who do not have a certified quality assurance scheme.

Type B for suppliers who do not have a certified quality assurance scheme but have access to an accredited laboratory.

Type C for suppliers who have a certified quality assurance scheme but do not have access to an accredited laboratory.

Type D for suppliers who have both a certified quality assurance scheme and access to an assessed laboratory.

These declarations are more specific than those based on systems used for steels included in BS EN 10204 ‘Metallic Products – Types of Inspection Documents’.