S-Cu-6 (CS051B) Grade Overview
S-Cu-6, recorded under the number CS051B, is a copper alloy scrap grade defined in EN 12861:1999, the European standard covering copper and copper alloys in scrap form. It occupies the middle of the purity range: the grade requires a minimum of 99.7 % copper including silver, with oxygen held to 0.06 %, and it applies individual ceilings to iron, nickel, aluminium, lead, zinc, tin and bismuth instead of a single residual allowance. That structure makes CS051B a predictable melt stock for copper products that need good conductivity together with reliable hot and cold workability.
The classification is copper alloy scrap and the grade carries no listed equivalents, so its identity is established by analysis rather than by trade name. For a smelter, a rod mill or a strip producer, the practical value of the grade lies in the fact that every residual that can damage either conductivity or formability is individually controlled.
Chemical Composition of S-Cu-6 (CS051B)
All figures below are maxima unless a minimum is shown. Silver is counted with the copper content, the oxygen content is limited to 0.06 %, and unlisted elements are restricted to the general residual allowance.
| Element | Limit, % | Effect on processing |
|---|---|---|
| Cu including Ag | min 99.7 | Base metal content |
| O | max 0.06 | Governs porosity and hydrogen behaviour in melting |
| Fe | max 0.04 | Raises strength, lowers conductivity |
| Ni | max 0.01 | Retained in solution, affects conductivity |
| P | max 0.001 | Dominant threat to electrical conductivity |
| Al | max 0.02 | Oxide inclusions and casting defects |
| Pb | max 0.04 | Hot-shortness in rolling and drawing |
| Zn | max 0.04 | Volatilises in the melt, fume and zinc loss |
| Sn | max 0.04 | Raises hardness, reduces ductility |
| Bi | max 0.0005 | Grain-boundary embrittlement |
| Other elements | each max 0.002 | General residual allowance |
The combination of a 99.7 % copper minimum with a 0.06 % oxygen ceiling is what separates this grade from lower scrap categories. Oxygen is not a residual impurity in the usual sense: above the limit it produces steam-related porosity during casting and makes the melt sensitive to hydrogen, so the ceiling is a process-control requirement rather than an analysis formality.
Standard Basis and Designation Rules
EN 12861:1999 fixes the designation, sampling and characterisation of copper and copper alloy scrap and sets the chemical limits that separate one grade from another. It lists no equivalent grades for S-Cu-6, so a substitution must be supported by agreed analysis. Two deliveries described in identical commercial language can still differ in iron, tin or zinc by a factor of several, and each of those elements moves the hardness, conductivity and forming behaviour of the finished copper product.
A grade claim is proven by chemical analysis of a representative sample of the lot.
Sampling must cover the whole consignment, because scrap is not a homogeneous material.
Mixed alloys, plated or soldered material, coatings, oil and moisture must be removed before charging.
Casting and Condition Designations Used with the Grade
The record additionally carries the standard letter codes for casting route and delivery condition that appear throughout copper alloy specifications. They describe how the material is produced or ordered and do not alter the chemistry limits.
GS – sand casting
GM – permanent mould casting
GZ – centrifugal casting
GC – continuous casting
GP – pressure die casting
R – condition defined by a minimum tensile strength, with tensile strength and elongation mandatory
H – condition defined by a minimum hardness, with hardness mandatory
The usual mechanical property symbols, ReH for minimum yield strength, Rm for tensile strength, A for minimum elongation and J for the notch impact test, are also listed. For a scrap grade these are not mandatory limits and become contractual only when a cast product is ordered to a stated condition.
Inspection, Sampling and Melt-Shop Practice
Verification of CS051B runs in two stages. Physical sorting removes mixed alloy, soldered or plated items, insulation and damp material, and prepares the lot for representative sampling. Instrumental checking follows, using X-ray fluorescence or spark analysis on prepared samples, and the composition is confirmed again by a bath analysis after melting and before casting. Because iron, tin and zinc are each capped at 0.04 % while copper must reach 99.7 %, the grade rewards careful segregation of the incoming material far more than it rewards refining capability.
The grade is charged for wire rod, strip and other copper products where a moderate iron and tin level is acceptable and where the low phosphorus and bismuth content protects ductility through cold reduction. Its individually controlled residuals also make the melting behaviour predictable, which simplifies furnace scheduling and reduces the risk of an off-analysis heat.
Frequently Asked Questions
Q: What is S-Cu-6 CS051B?
It is a copper alloy scrap grade defined in EN 12861:1999 with a minimum of 99.7 % copper including silver and individual limits on iron, nickel, aluminium, lead, zinc, tin and bismuth.
Q: Why is oxygen limited to 0.06 %?
Above that level oxygen causes porosity during casting and makes the melt sensitive to hydrogen, so the ceiling is a casting-process requirement rather than a simple impurity limit.
Q: Which standard defines the grade?
EN 12861:1999, the European standard for copper and copper alloys in scrap form, which fixes both the designation and the chemical limits.
Q: Are equivalent grades available for S-Cu-6?
No equivalents are listed, so any substitute must be qualified by agreed chemical analysis against the specified limits.
Q: How is the lots composition verified?
By physical sorting, sampling, X-ray fluorescence or spark analysis, and a final bath analysis after melting and before casting confirms the heat.
Q: What does the grade designation CS051B mean?
It is the grade number recorded for this material; the grade itself is identified as S-Cu-6, classified as copper alloy scrap, and defined by its chemical composition.
