H59 copper alloy is a type of high-zinc brass, belonging to the category of binary brass alloys. It is valued for its relatively low cost, good castability, and moderate mechanical properties, making it widely used in various industrial and manufacturing fields. Below is a detailed overview:
Chemical Composition
The composition of H59 brass is primarily dominated by copper and zinc, with strict control over impurity elements to ensure stable performance:
Copper (Cu): Content ranges from 57% to 60%. Copper is the key element that provides the alloy with basic properties such as conductivity, ductility, and corrosion resistance.
Zinc (Zn): The remaining portion is mainly zinc (approximately 40%–43%). The high zinc content reduces the material cost while enhancing strength and hardness, though it may slightly lower ductility compared to lower-zinc brasses (e.g., H62).
Impurities: Trace elements are strictly limited to avoid adverse effects, including: lead (Pb) ≤0.5%, iron (Fe) ≤0.3%, tin (Sn) ≤0.2%, nickel (Ni) ≤0.2%, and total impurities ≤1.0%. (Note: Specific impurity limits may vary slightly by industry standards.)
Physical Properties
Density: Approximately 8.4–8.5 g/cm³, similar to other brass alloys, making it lightweight relative to some metals while maintaining structural stability.
Melting point: Ranges from 880°C to 920°C, lower than pure copper, which facilitates casting and hot working processes.
Thermal conductivity: About 100–120 W/(m·K), lower than pure copper but sufficient for applications with moderate heat transfer requirements.
Electrical conductivity: Approximately 25%–30% IACS (International Annealed Copper Standard), suitable for non-critical electrical applications where high conductivity is not the primary demand.
Coefficient of linear expansion: Around 21×10⁻⁶/°C, ensuring reasonable dimensional stability in environments with moderate temperature fluctuations.
Mechanical Properties
H59 brass exhibits mechanical properties that balance strength and processability, with variations depending on the manufacturing process (e.g., casting, forging, or cold working):
Tensile strength: 290–420 MPa (higher than some low-zinc brasses due to the strengthening effect of zinc).
Yield strength: 180–280 MPa, indicating moderate resistance to plastic deformation under load.
Elongation: 10%–20% (lower than H62 brass, reflecting slightly reduced ductility due to higher zinc content).
Hardness: Brinell hardness of 75–120 HB, providing good wear resistance for general structural applications.
Processing Performance
Casting performance: Excellent castability is one of the most prominent advantages of H59 brass. It can be easily shaped using processes such as sand casting, die casting, and investment casting, making it suitable for complex-shaped parts.
Hot working performance: Performs well in hot working (e.g., hot forging, hot rolling) at temperatures between 600°C and 800°C, allowing for the production of forged components or large-sized profiles.
Cold working performance: Has limited cold workability compared to lower-zinc brasses. Cold deformation (e.g., cold drawing, stamping) may cause work hardening, requiring intermediate annealing to restore ductility if high deformation is needed.
Machinability: Good machinability, enabling smooth surface finishes and precise dimensions during turning, milling, or drilling operations, which is beneficial for manufacturing hardware and mechanical parts.
Weldability: Can be welded using methods like brazing and resistance welding, but arc welding may be challenging due to potential zinc evaporation, which can affect joint strength.
Corrosion Resistance
H59 brass offers moderate corrosion resistance in general environments:
Resists atmospheric corrosion and performs adequately in freshwater, forming a thin protective oxide layer over time.
Limitations: Susceptible to corrosion in harsh environments, such as seawater (due to chloride ions), acidic or alkaline solutions, and ammonia-containing media. It may also experience “dezincification” in certain conditions, where zinc is selectively corroded, leaving a porous copper structure that weakens the material.
Application Fields
Due to its cost-effectiveness and castability, H59 brass is widely used in:
Hardware manufacturing: Producing daily hardware items such as valves, faucets, pipe fittings, hinges, and bolts, leveraging its machinability and moderate strength.
Mechanical components: Manufacturing gears, bearings, bushings, and connecting rods for low-load machinery, where its wear resistance and castability are advantageous.
Plumbing and piping: Used in water supply pipes, elbows, and connectors for non-critical water systems (avoiding highly corrosive environments).
Decorative parts: Cast into decorative items, statues, and ornaments, as it can be polished to a bright finish and is more affordable than higher-copper alloys.
Automotive and industrial accessories: Producing small cast components for automotive interiors, instrument panels, and industrial equipment.
Comparison with Similar Alloys
vs. H62 brass: H59 has higher zinc content, lower copper content, and lower ductility but better castability and lower cost. H62 is preferred for applications requiring higher ductility and corrosion resistance (e.g., electrical parts, precision components).
vs. H68 brass: H59 is stronger but less ductile than H68, which has higher copper content and better formability for deep drawing or stamping.
In summary, H59 copper alloy is a cost-effective, castable brass suitable for non-critical structural, hardware, and decorative applications where high conductivity or extreme corrosion resistance are not required. Its balance of properties makes it a practical choice in mass-produced industrial and consumer products.