What Is the Density of Copper Alloys - Knowledge

1. General Density Range of Copper Alloys

The density of copper alloys typically ranges from 8.2 g/cm³ to 9.5 g/cm³, which is lower than pure copper (≈8.96 g/cm³) in most cases (exceptions include high-nickel cupronickel). This variation stems from the density of alloying elements:

Elements with lower density than copper (e.g., Zn: 7.14 g/cm³, Al: 2.70 g/cm³, Sn: 7.31 g/cm³) reduce the overall alloy density when added.

Elements with higher density than copper (e.g., Ni: 8.91 g/cm³, Fe: 7.87 g/cm³, Be: 1.85 g/cm³-note: Be is added in trace amounts, so its impact is negligible) have a minimal or slightly increasing effect on density.

2. Density of Common Copper Alloy Grades (Classified by Type)

To facilitate practical application (e.g., weight calculation for mechanical design, cost estimation in foreign trade), the density of typical commercial grades is listed below (data based on ASTM/ISO standards, applicable to annealed state):

Alloy Category	Common Grades	Chemical Composition (Key Elements)	Density (g/cm³)	Typical Applications
Brass (Cu-Zn)	C26000 (Cartridge Brass)	Cu: 68–70%, Zn: 30–32%	8.47	Valves, fittings, electrical connectors
	C36000 (Free-Cutting Brass)	Cu: 60–63%, Zn: 35–38%, Pb: 2–3%	8.50	Screws, nuts, precision machined parts
	C46400 (Naval Brass)	Cu: 60%, Zn: 39%, Sn: 1%	8.53	Marine hardware, propeller shafts
Bronze (Cu-Sn/Al/Be)	C51000 (Phosphor Bronze)	Cu: 94–96%, Sn: 4–6%, P: 0.1–0.3%	8.80	Springs, bearings, electrical contacts
	C60800 (Aluminum Bronze)	Cu: 85–88%, Al: 10–12%, Fe: 2–3%	8.70	Valves, gears, marine corrosion-resistant parts
	C17200 (Beryllium Bronze)	Cu: 97–98%, Be: 1.6–2.0%, Ni: 0.2–0.6%	8.73	High-strength springs, aerospace components
Cupronickel (Cu-Ni)	C70600 (90/10 Cupronickel)	Cu: 88–90%, Ni: 9–11%, Fe: 0.8–1.2%	8.94	Marine pipes, heat exchangers
	C71500 (70/30 Cupronickel)	Cu: 68–72%, Ni: 28–32%, Fe: 0.4–1.0%	8.99	Ship hulls, desalination equipment
Copper-Nickel-Zinc (Nickel Silver)	C75200 (18% Nickel Silver)	Cu: 65%, Ni: 18%, Zn: 17%	8.64	Decorative parts, musical instruments
Copper-Chromium-Zirconium (Cu-Cr-Zr)	C18150 (Chromium Copper)	Cu: 98.8–99.4%, Cr: 0.5–1.0%, Zr: 0.1–0.2%	8.90	Welding electrodes, high-current busbars

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3. Density Differences Among Different Grades: Significant or Not?

The density difference among copper alloy grades is moderate (≤8% maximum variation) and not extreme. Specifically:

Within the same alloy category: Density varies slightly (≤2%). For example:

Brass grades (C26000: 8.47 g/cm³; C36000: 8.50 g/cm³) differ by only 0.35% due to similar Zn content.

Cupronickel grades (C70600: 8.94 g/cm³; C71500: 8.99 g/cm³) have minimal variation because Ni and Cu have similar densities.

Across different alloy categories: Density differences are more noticeable (2–8%). For example:

Aluminum bronze (C60800: 8.70 g/cm³) is 3.2% less dense than beryllium bronze (C17200: 8.73 g/cm³) due to Al's lower density.

Naval brass (C46400: 8.53 g/cm³) is 5.2% less dense than 70/30 cupronickel (C71500: 8.99 g/cm³) due to higher Zn content in brass.

Key Takeaway:

Density differences among copper alloy grades are not significant enough to cause drastic performance changes (e.g., structural strength, corrosion resistance). However, they are critical for:

Weight-sensitive applications (e.g., aerospace components, automotive parts) where precise density data ensures accurate weight calculations.