1. What Material is C22000?
C22000 is a copper-zinc alloy (classified as "commercial bronze" or "cartridge brass") under the UNS (Unified Numbering System) standard. Despite its common name "bronze," it is technically a type of brass-distinguished by zinc as the primary alloying element (unlike traditional bronze, which is copper-tin based). C22000 is renowned for its excellent ductility, formability, machinability, and corrosion resistance, making it one of the most widely used brass alloys in industrial and consumer applications. It complies with international standards such as ASTM B111, B152, and B280, and is equivalent to European grade CW505L, Japanese grade C2200, and Chinese grade H90 (GB/T 5231).
2. What Color is the Surface of C22000?
The surface of C22000 exhibits a bright golden-yellow to yellowish-brown hue-a characteristic appearance of high-copper brass. This color is attributed to its high copper content (90% Cu, typical). When freshly polished or processed, it has a glossy, metallic luster resembling gold. Over time, exposure to air, moisture, or mild corrosive environments will cause a thin, protective patina to form, gradually darkening the surface to a deeper bronze-like tone (reddish-brown). However, this patina is non-destructive and can be restored to its original golden color through polishing or surface treatment (e.g., plating, passivation).
3. What is the Chemical Composition of C22000?
C22000's chemical composition is standardized by international bodies (e.g., ASTM, ISO) to ensure consistent performance. The key components (per ASTM B111/B111M and UNS specifications) are as follows:
| Element | Content Range | Role |
|---|---|---|
| Copper (Cu) | 88.0–92.0% | Base metal; provides corrosion resistance, ductility, and conductivity. |
| Zinc (Zn) | 8.0–12.0% | Primary alloying element; enhances strength and formability while maintaining a golden color. |
| Lead (Pb) | ≤0.07% | Trace impurity (or controlled additive in some variants); improves machinability. |
| Iron (Fe) | ≤0.10% | Trace impurity; must be limited to avoid reducing ductility. |
| Nickel (Ni) | ≤0.30% | Trace impurity; may slightly improve corrosion resistance. |
| Tin (Sn) | ≤0.20% | Trace impurity; minimal impact on properties. |
| Total Impurities | ≤0.50% | Sum of all minor elements (excluding Cu and Zn) to ensure purity. |
