C28000 is the ordinary 60/40 brass of the drawn-bar and machined-parts world. It sits between the highly ductile 70/30 grade and the free-cutting leaded brasses, offering more strength than either low-zinc brass or pure copper at a moderate cost, together with corrosion resistance, thermal and electrical conductivity, and machining behaviour that suits automatic production.
What C28000 Material Is
C28000, historically called Muntz metal, contains approximately 60 % copper and 40 % zinc. At that composition the alloy is a two-phase mixture of alpha and beta grains, so it is harder and more rigid than the lower-zinc brasses and it work hardens quickly. The beta phase also gives the alloy its distinctive warm gold colour, close to architectural bronze, which is why polished and lacquered parts are often left unfinished on exterior hardware.
Chemical and Mechanical Profile
| Item | Requirement |
|---|---|
| Copper (Cu) | 59.0 – 63.0 % |
| Zinc (Zn) | Balance |
| Lead (Pb) | Low residual, limited by the applicable product standard |
| Density | 8.39 g/cm³ (0.303 lb/in³) |
| Melting range | approximately 900 – 940 °C |
| Electrical conductivity (annealed) | about 28 % IACS |
| Thermal conductivity | about 120 W/(m·K) |
| Modulus of elasticity | about 103 GPa |
Tensile strength and elongation are specified per temper, so the buyer orders a temper line and the standard supplies the acceptance values for that line. The general behaviour is predictable: annealed material is the most formable, drawn tempers add strength, and the extra hard tempers are reserved for parts that must resist wear or hold a thread under load.
International Equivalents
| System | Designation | Copper content |
|---|---|---|
| UNS | C28000 | 59.0 – 63.0 % |
| China | H62 (GB/T 4423 drawn bar) | 60.5 – 63.5 % |
| Japan | C2800 (JIS H3250) | 59.0 – 63.0 % |
| Older European designation | CuZn40 | about 60 % nominal |
These designations describe the same 60/40 family, with minor differences in the permitted copper band and residual element limits. Where a drawing quotes one system and the mill certificate quotes another, the ordered grade controls acceptance, and the difference in copper band must be understood before the two are treated as identical.
Machining, Forming and Joining
Machining: the beta phase produces short chips and good surface finish on automatic lathes; positive rake tooling, sharp edges and generous coolant give long tool life.
Cold working: limited. Bending and coining are practical, but heavy reduction requires intermediate annealing because the alloy hardens rapidly.
Hot working: the alloy is ductile in the elevated temperature range where the beta phase deforms readily, which is why extrusion and hot forging routes are common.
Joining: soldering and brazing are straightforward and widely used in plumbing and electrical assemblies; fusion welding requires controlled heat input to limit zinc loss.
Finishing: the alloy polishes to a bright gold finish, takes clear lacquer well and can be tinned or plated after standard cleaning.
Typical Applications
Machined parts dominate: bar stock is turned into fittings, bushes, nuts, valve bodies and stems, electrical terminals, decorative hardware, marine fasteners and architectural sections. The alloy is also used for pipe and tube in water systems and for stamped parts where strength matters more than deep drawability.
One demanding application deserves specific mention. High-precision hydraulic valve components must control oil flow with minimal leakage, so bores, spools and seats are held to close tolerances and fine surface finish. C28000 machined in a suitable temper holds those tolerances, resists the slight acidity of hydraulic fluid, and does not gall against mating brass or steel parts as readily as a softer alloy; where the valve sees high sliding loads, a harder drawn temper or a different copper alloy is selected after reviewing wear duty.
FAQ
Q: What is C28000 brass material?
It is the 60/40 copper-zinc alloy known as Muntz metal, supplied as drawn bar, tube, strip and plate and used mainly for machined and wet-service components.
Q: Is C28000 the same as H62?
They belong to the same 60/40 family. The UNS grade is specified at 59.0 – 63.0 % copper and the Chinese GB/T 4423 H62 grade at 60.5 – 63.5 % copper.
Q: Why does C28000 work harden so quickly?
Its beta phase deforms less readily than the alpha phase of low-zinc brasses, so strength rises fast during cold reduction and intermediate annealing becomes necessary.
Q: Can C28000 be used for hydraulic valve bodies?
Yes, in a temper suited to the machining and wear duty, with tolerances and surface finish specified for the sealing function of the valve.
Q: Does the alloy resist sea water?
It resists marine air and salt spray well and has long marine history, but continuous aggressive chloride exposure is reviewed for dezincification before approval.
Q: How is C28000 ordered?
By grade, product form, temper, dimensions and the governing standard, supported by a certificate of analysis and the mechanical test results for the ordered temper.
