Two Ordinary Brasses That Cover Most Applications
H59 and H62 are binary copper-zinc alloys designated under the Chinese GB/T 5231 system, and together they account for a very large share of ordinary brass consumption in hardware, plumbing, electrical and general engineering products. Both are duplex alpha plus beta structures, both are readily available as plate, strip, rod, tube and wire, and both are economical compared with the higher-copper brasses. The differences between them lie in copper content, and copper content controls almost everything else: strength, ductility, hot working behaviour, corrosion resistance and price.
In simple terms, H62 buys balance and workability, while H59 buys strength and cost efficiency at the expense of ductility and corrosion performance.
Chemical Composition Under GB/T 5231
The composition windows are narrow but decisive. H62 sits close to the boundary where the beta phase becomes a major constituent, while H59 is further into the duplex field.
| Element | H59 | H62 |
|---|---|---|
| Copper (Cu), % | 57.0 to 60.0 | 60.5 to 63.5 |
| Zinc (Zn), % | Balance | Balance |
| Iron (Fe), % max | 0.3 | 0.15 |
| Lead (Pb), % max | 0.5 | 0.08 |
| Total other impurities, % max | 1.0 | 0.5 |
| Phase structure | Alpha plus beta duplex | Alpha plus beta duplex |
The wider impurity allowances in H59 are one reason it is the lower-cost grade: less pure cathode and more recycled input can be used while still meeting the specification. Where a purchase order states only brass, the delivered grade is often the cheapest one that satisfies the drawing, so the copper content should always be verified against the certificate of analysis.
Mechanical and Physical Properties
Property values depend strongly on temper and product form, so the table below gives representative ranges rather than guaranteed minima. Actual requirements should be quoted against the relevant product-form standard, such as the plate, strip, rod or tube standard applicable to the grade.
| Property | H59 typical | H62 typical |
|---|---|---|
| Density | About 8.4 g/cm³ | 8.43 g/cm³ |
| Tensile strength | 315 to 350 MPa | 372 to 540 MPa |
| Yield strength | 200 to 250 MPa | 250 to 360 MPa |
| Elongation | 35 to 45% in soft temper | 30% and above, temper dependent |
| Hardness | About 60 to 80 HRB | About 85 to 120 HV |
| Electrical conductivity | Lower, following the lower copper content | About 27% IACS |
H62 therefore offers a higher strength ceiling for a comparable section and better electrical conductivity, while H59 is chosen where the requirement is essentially strength and hardness at minimum material cost.
Corrosion Behaviour and Dezincification
Both grades rely on a protective surface film, but the higher zinc content of H59 makes it more susceptible to dezincification, the selective leaching of zinc that leaves a weak, porous copper residue. In potable water, mildly acidic condensate or continuously wet service, H59 is a poor choice and H62 is only adequate in low-risk conditions. Where dezincification resistance is a design requirement, the correct answer is an inhibited or higher-copper alloy, or an alloyed brass containing tin, aluminium or arsenic as an inhibitor, rather than either of these two ordinary grades.
Atmospheric and dry indoor service: both grades perform acceptably.
Fresh water and condensate: prefer H62; avoid H59 for permanent wetted parts.
Marine and chloride-rich environments: neither grade is suitable without additional alloying.
Ammonia-bearing atmospheres: both are at risk of stress corrosion cracking if residual stresses are not relieved.
Applications and Selection Guidance
H59: fasteners, nuts, washers, fittings, hardware, decorative castings, brackets and general pressed parts where strength and cost dominate.
H62: plumbing and heating fittings, valves, connectors, radiator parts, electrical terminals, stamped and deep-drawn components, and general machined parts where a balance of strength and ductility is needed.
Neither grade is the right answer for high-volume automatic screw machining; a leaded free-cutting brass is specified for that duty, subject to the lead restrictions of the destination market.
When a project is split across several component types, one practical approach is to standardise on H62 for all cold-formed and machined parts and reserve H59 for low-risk, cost-sensitive hardware. This keeps one set of forming parameters, one annealing schedule and one set of inspection criteria, which usually saves more in scrap and setup time than the raw-material difference between the two grades.
FAQ
Q: What is the main difference between H59 and H62 brass?
Copper content. H59 contains 57.0 to 60.0 percent copper and H62 contains 60.5 to 63.5 percent, so H62 is more ductile, more corrosion resistant and more expensive, while H59 is stronger and cheaper.
Q: Which grade is better for outdoor use?
H62. Its lower zinc content gives it better resistance to dezincification and atmospheric attack, while H59 is best kept to dry indoor service or non-critical hardware.
Q: Can H59 and H62 be interchanged freely?
No. They are close enough that a low-stress part may work in either, but tensile strength, elongation and corrosion life differ, so substitution requires engineering approval and a check of the forming and annealing schedule.
Q: What is the density of H59 and H62 brass?
Approximately 8.4 g/cm³ for H59 and 8.43 g/cm³ for H62 at room temperature, both of which are used directly for calculating strip and plate weight.
Q: Which grade is easier to machine?
Both ordinary grades machine less freely than leaded free-cutting brass. Of the two, H62 machines somewhat better because its duplex structure promotes cleaner chip formation.
Q: Are H59 and H62 suitable for hot working?
Yes. Both are duplex brasses with good hot deformability. H62 is typically hot worked around 700 to 750 degrees Celsius, and H59 tolerates a broad hot working range, which is one reason it is common in hot-forged fittings.
Q: How should the delivered grade be verified?
By chemical analysis on the certificate of analysis, covering copper, iron, lead and total impurities against the GB/T 5231 limits for the ordered grade.
