UNS C67500, traditionally known as "Manganese Bronze," is a powerful metallurgical anomaly. Despite its trade name, it is technically not a true bronze (copper-tin), but rather a highly alloyed, high-tensile Alpha-Beta Brass (copper-zinc). By heavily modifying a standard 60/40 brass matrix with deliberate additions of Iron, Tin, and Manganese, the alloy achieves a massive surge in mechanical strength and wear resistance, allowing it to easily carry heavy dynamic loads.
The true engineering value of C67500 lies in its phenomenal hot-forging capabilities combined with its ability to withstand extreme metal-to-metal friction. It acts as an excellent bearing material, making Manganese Bronze fasteners the traditional heavyweight choice for high-load, low-speed mechanical joints, heavy construction equipment, marine brackets, and heavy-duty pump rods where structural rigidity and anti-galling properties are mandatory.
| Material Classification | High-Tensile Brass (Manganese Bronze) |
|---|---|
| UNS Designation | C67500 |
| Microstructure | Dual-Phase (Alpha-Beta) Solid Solution |
| Magnetic State | Low Magnetic Permeability (Slightly magnetic due to Iron content) |
| Density | 8.36 g/cm³ (0.302 lb/in³) |
| Size Range | Metric: M6 to M64 | Imperial: 1/4" to 2-1/2" |
| Primary Attribute | Excellent Hot Forgeability & High-Load Wear Resistance |
Contains detailed extreme-friction anti-galling limits, optimal hot-forging temperatures for massive marine bolts, and structural shear thresholds for heavy mechanical assemblies.
⬇ DOWNLOAD DATASHEETIn high-load mechanical environments, verifying the precise Iron and Manganese additions is critical to ensuring the metal does not yield or deform under heavy friction. Every lot of C67500 shipped by Ananka includes fully verified mill traceability.
C67500 uses a traditional brass base (~58% Copper, ~39% Zinc) but supercharges it. The addition of Iron (0.8% - 2.0%) refines the grain structure and vastly increases tensile strength. The Manganese and Tin work synergistically to improve seawater corrosion resistance and increase the hardness of the beta-phase crystals.
| Copper (Cu) | Zinc (Zn) | Iron (Fe) | Tin (Sn) | Manganese (Mn) | Lead (Pb) |
|---|---|---|---|---|---|
| 57.0 – 60.0 | Balance (~37.0 – 40.0) | 0.80 – 2.00 | 0.50 – 1.50 | 0.05 – 0.50 | 0.20 Max |
| Mechanical Property | Typical Limits (Half-Hard / Hot Forged) |
|---|---|
| Tensile Strength | 65,000 - 84,000 psi (450 - 580 MPa) |
| Yield Strength | 30,000 - 50,000 psi (205 - 345 MPa) |
| Elongation (in 2 inches) | 20% - 33% |
| Hardness (Rockwell B) | 75 - 90 HRB |
| Standard / System | Designation |
|---|---|
| ASTM Specifications | ASTM B138 (Rod, Bar, and Shapes), ASTM F467/F468 |
| Common Trade Names | Manganese Bronze A, High-Tensile Brass, Alloy 675 |
| European Equivalent | EN CW721R / CuZn40Mn1Pb1 (Approximate) |
| Military / Automotive Std | SAE J461 / SAE J463 |
| Mating Bolts/Studs | Internal Threads (Nuts) | Washers |
|---|---|---|
| C67500 Hot Forged Hex Bolts & Pump Shafts | C67500 Heavy Hex Nuts | C67500 or C46400 Washers |
C67500 handles mechanical stress beautifully, exhibiting strength levels similar to Naval Brass and mild steel. Because it serves as an excellent bearing material, it is less prone to sudden thread galling than Silicon Bronze, though high-pressure lubricants are still required for heavy marine assemblies.
| Nominal Diameter | Threads Per Inch (UNC) | Max Target Torque (in-lbs) | Max Target Torque (ft-lbs) |
|---|---|---|---|
| 1/4" | 20 | 70 - 80 | ~ 6.5 |
| 3/8" | 16 | 200 - 220 | ~ 17.5 |
| 1/2" | 13 | 400 - 450 | ~ 35 |
| 3/4" | 10 | 1300 - 1500 | ~ 115 |
The term "Manganese Bronze" is a historic, commercial misnomer that stuck around. In metallurgy, any alloy primarily combining Copper and Zinc is a brass. Because this specific alloy was so incredibly strong, wear-resistant, and visually resembled true bronze after weathering, early engineers branded it as a "bronze" to signify its heavy-duty, high-performance nature. Today, metallurgists formally classify it as a High-Tensile Brass.
Generally, no. The Iron, Manganese, and high Zinc content create a rigid "beta-phase" crystalline structure. Attempting to aggressively cold-head or severely bend C67500 at room temperature will cause it to fracture. Instead, Manganese Bronze exhibits absolutely spectacular hot-forging properties. Massive hex bolts and heavy structural components are easily formed by heating the metal to a red-hot, malleable state before striking.
Yes, but very slightly. Because the alloy relies on a deliberate addition of 0.8% to 2.0% Iron to achieve its high tensile strength, it possesses a low magnetic permeability. While you cannot pick it up with a standard magnet, it is absolutely not suitable for hyper-sensitive magnetic environments (like MRI machines or directional drilling compass housings) where 100% non-magnetic materials like C17200 Beryllium Copper or C51000 Phosphor Bronze are required.
