1. Classification of Pure Copper Grades
ASTM UNS System (C10000 Series)
The UNS (Unified Numbering System) for copper and copper alloys assigns a five‑digit number starting with "C". Pure copper falls within the range C10100 to C13000, and is categorized by oxygen content and purity:
Oxygen‑Free Electronic Copper (OFE): Represented by C10100. It has an extremely high purity (≥99.99% Cu) and ultra‑low oxygen content (≤0.001%). It is produced via non‑oxidizing melting, offering the highest electrical conductivity (≥102% IACS) and excellent resistance to hydrogen embrittlement.
Oxygen‑Free High Conductivity Copper (OFHC): Represented by C10200. Purity ≥99.95% Cu, oxygen ≤0.001%. It is the standard grade for high‑performance electrical applications.
Electrolytic Tough Pitch Copper (ETP): Represented by C11000. Purity ≥99.90% Cu, with a controlled oxygen content (typically 0.02–0.04%). It is the most widely used general‑purpose pure copper grade, balancing performance and cost.
Phosphorus‑Deoxidized Copper: Grades like C12000 and C12200, containing trace phosphorus for deoxidation, improving weldability.
Chinese GB/T System (GB/T 5231)
Chinese pure copper grades start with the letter "T" (for "Tong," meaning copper). They are divided into three main categories based on purity and oxygen content:
Common Pure Copper (T‑series):
T1: High purity (≥99.95% Cu), low impurities, used for precision electrical components.
T2: The most common grade (≥99.90% Cu), widely used in wires, cables, pipes, and general industry.
T3: Lower purity (≥99.70% Cu), cost‑effective for non‑critical applications.
Oxygen‑Free Copper (TU‑series):
TU1: Ultra‑low oxygen (≤0.001%), highest purity, equivalent to C10100.
TU2: Low oxygen (≤0.002%), equivalent to C10200.
Phosphorus‑Deoxidized Copper (TP‑series):
TP1/TP2: Contain phosphorus for deoxidation, used in welding and heat‑exchanger applications.
2. Chinese Equivalents of C10100 and C11000
C10100 (Oxygen‑Free Electronic Copper, OFE):
Chinese Equivalent: TU1 (GB/T 5231).
Both are ultra‑high‑purity, oxygen‑free coppers (Cu ≥99.99%, O ≤0.001%), designed for critical electronic, vacuum, and superconducting applications where hydrogen embrittlement must be avoided.
C11000 (Electrolytic Tough Pitch Copper, ETP):
Chinese Equivalent: T2 (GB/T 5231).
Both are general‑purpose, high‑conductivity coppers with similar purity (Cu ≥99.90%) and controlled oxygen levels. They are interchangeable in most industrial and electrical applications.
In summary, pure copper grading is standardized globally to ensure material consistency. C10100 corresponds to China's TU1 (ultra‑high‑purity oxygen‑free copper), while C11000 corresponds to T2 (general‑purpose tough‑pitch copper).
