1. What are the core properties of C28000?
Mechanical Strength: High tensile strength (380–600 MPa, depending on temper) and good yield strength (140–450 MPa), significantly stronger than low-zinc brasses (e.g., C22000) due to zinc solid-solution strengthening.
Formability: Excellent hot workability (forging, extrusion, rolling at 600–800°C) and moderate cold workability (bending, stamping for thin gauges); ductile enough for complex-shaped components but less malleable than pure copper or low-zinc brasses.
Corrosion Resistance: Good resistance to atmospheric corrosion, fresh water, and neutral salts; forms a protective patina layer. However, it is susceptible to dezincification in aggressive environments (e.g., marine, acidic/alkaline media) without proper alloying or surface treatment.
Machinability: Superior machinability (rated ~80 on the brass machinability scale), enabling efficient turning, drilling, tapping, and milling-ideal for high-volume production of precision parts.
Physical Properties: Density (~8.53 g/cm³), melting point (900–940°C), moderate thermal conductivity (~110 W/m·K), and low electrical conductivity (~20 IACS %)-lower than pure copper but sufficient for non-critical electrical applications.
Aesthetic Appeal: Bright golden-yellow color with good polishability, suitable for decorative and architectural uses.
2. What are the advantages of C28000?
Excellent Strength-to-Cost Ratio: Offers higher mechanical strength than low-zinc brasses (e.g., C22000) and pure copper at a competitive price, making it a cost-effective choice for load-bearing components.
Superior Machinability: Outperforms most copper alloys and low-zinc brasses in machining efficiency, reducing production time, tool wear, and manufacturing costs-especially for complex or precision-machined parts (e.g., valves, fittings, fasteners).
Exceptional Hot Workability: Thrives in high-temperature processing (forging, extrusion), allowing for the production of large or thick-walled components (e.g., marine hardware, structural parts) that require shaping at elevated temperatures.
Good Ductility & Formability: Balances strength with sufficient ductility for cold forming processes (e.g., bending, stamping) and assembly operations (e.g., riveting, brazing), expanding its application scope.
Aesthetic Versatility: Natural golden-yellow hue and polishability make it suitable for both functional and decorative applications (e.g., architectural trim, musical instruments, consumer goods).
Widely Available: A standard brass alloy with global supply chain support, available in various forms (sheets, plates, bars, tubes, forgings) and tempers to meet diverse customer needs.
3. What are the disadvantages of C28000?
Susceptibility to Dezincification: High zinc content (40%) makes it prone to dezincification-a corrosion mechanism where zinc is leached from the alloy, leaving a porous, brittle copper-rich structure. This limits its use in marine environments, acidic/alkaline solutions, or high-humidity/corrosive atmospheres without protective coatings (e.g., nickel plating) or dezincification-resistant (DZR) modifications.
Poor Resistance to Stress Corrosion Cracking (SCC): Under tensile stress and exposure to aggressive media (e.g., ammonia, chlorides), C28000 may develop SCC-cracking that can lead to sudden component failure. It is not recommended for high-stress applications in corrosive environments.
Lower Electrical & Thermal Conductivity: Conductivity is significantly lower than pure copper, oxygen-free copper (e.g., C11000), or low-zinc brasses, making it unsuitable for high-current electrical applications (e.g., power cables, transformer windings) or high-efficiency thermal management systems (e.g., heat exchangers for critical equipment).
Reduced Cold Workability Compared to Low-Zinc Brasses: While moderately formable, C28000 is less ductile than low-zinc alloys (e.g., C22000) in cold conditions. It may crack or deform if subjected to excessive cold working (e.g., deep drawing of thick materials) without intermediate annealing.
Not Suitable for High-Temperature Corrosive Environments: Beyond 200°C, its corrosion resistance and mechanical stability degrade, limiting use in high-temperature industrial processes (e.g., chemical reactors, high-heat machinery) or applications with prolonged exposure to elevated temperatures.
Brittleness at Low Temperatures: In cryogenic or extremely low-temperature environments, C28000 may become brittle, reducing its toughness and reliability for applications in cold climates or low-temperature equipment.
