For a large proportion of turned and milled brass components — particularly plumbing fittings, valve bodies, electrical terminals, and decorative hardware — H62 (CuZn37) is the cost-effective workhorse. It delivers a tensile strength above 290 MPa in the annealed condition (per GB/T 4423), machines with short, manageable chips far easier than stainless steels, and takes nickel or chrome plating without blistering. The trade-off: if your part needs the extreme free-cutting behavior of leaded brass, H62 is noticeably tougher on the tool, though you gain significantly better cold formability and weldability.
Grade Identity and Standards
H62 is a binary copper-zinc brass defined by Chinese standard GB/T 5231, with a nominal composition of 62% copper and 38% zinc. At room temperature H62 exists as a single-phase alpha brass — the zinc content is low enough that no brittle beta phase precipitates, which is what gives it its excellent cold-working behavior.
Several international equivalents exist, but they are approximations, not drop-in replacements (see also our copper alloy machining guide for broader material selection context):
- UNS C28000 (Muntz metal): nominally 60% Cu / 40% Zn — slightly lower copper than H62. C28000 is a two-phase alpha+beta brass at room temperature, so its cold formability and corrosion behavior differ from H62.
- EN CW507L / CuZn37: the closest European equivalent, at 62-64% Cu.
- JIS C3712: Japanese designation for a 58-62% Cu brass, overlapping the lower end of H62’s range.
Do not treat these as drop-in material substitutions without checking the exact specification revision, delivery condition, and the part’s forming and service requirements. A component qualified on CW507L may fall outside H62’s permitted impurity limits for elements like iron or lead, and vice versa.
Chemical Composition (GB/T 5231)
H62 is a tightly specified binary alloy. The zinc content is high enough to lower the material cost compared to higher-copper brasses such as H68 or C26000, but not so high that it pushes the microstructure into the two-phase zone under normal processing conditions.
| Element | Weight % | Standard |
|---|---|---|
| Cu | 60.5 – 63.5 | GB/T 5231 |
| Zn | Balance | — |
| Pb | ≤ 0.08 | GB/T 5231 |
| Fe | ≤ 0.15 | GB/T 5231 |
| Sb | ≤ 0.005 | GB/T 5231 |
| Bi | ≤ 0.002 | GB/T 5231 |
| P | ≤ 0.01 | GB/T 5231 |
| Total impurities | ≤ 0.5 | GB/T 5231 |
The low lead limit (< 0.08%) is what separates H62 from free-cutting brass grades like C36000 (CuZn36Pb3), which deliberately adds 2.5-3.7% lead for chip-breaking — a small composition difference that dramatically changes how the material behaves on a CNC lathe.
Supply Conditions and Mechanical Properties
H62 bar, rod, plate, and strip are supplied in several standard tempers per GB/T 4423 and GB/T 2040. The condition you order changes mechanical properties dramatically:
| Condition | Designation | Tensile Strength (MPa) | Elongation (%) | Hardness (HB) |
|---|---|---|---|---|
| Annealed | M (O60) | ≥ 290 | ≥ 40 | — |
| Half-hard | Y2 (H02) | ≥ 350 | ≥ 20 | — |
| Hard | Y (H04) | ≥ 410 | ≥ 10 | — |
| Extra hard | T | ≥ 590 | ≥ 2.5 | — |
Data source: GB/T 4423-2007, typical minima for rod/bar. Sheet values per GB/T 2040 may differ slightly. Always specify product form and applicable standard.
Key physical properties at 20°C, annealed condition:
- Density: ~8.43 g/cm³ (slightly lower than pure copper at 8.96)
- Melting range: ~899 – 906°C
- Electrical conductivity: ~27% IACS (international annealed copper standard)
- Thermal conductivity: ~116 W/(m·K)
- Modulus of elasticity: ~105 GPa
Service Behavior: Corrosion, Wear, and Temperature
H62 offers adequate atmospheric corrosion resistance for indoor and mild outdoor environments, but it is not marine-grade. In the presence of ammonia, amines, or moist sulfur compounds, H62 can suffer stress corrosion cracking (SCC) — a failure mode that catches engineers who assume “brass is corrosion-proof” without checking the service atmosphere.
Dezincification — selective leaching of zinc from the alloy, leaving a porous copper-rich surface — can occur in stagnant waters below pH 7.5. For fittings exposed to aggressive water, DZR brasses or bronze may be necessary. H62 itself is not classified as DZR.
Above approximately 200°C, H62 begins to soften as cold-work anneals out rapidly. Creep becomes measurable above ~150°C under sustained load. It is not for high-temperature structural applications.
CNC Machining H62: What to Expect
H62 machines well compared to most nonferrous alloys — far easier to cut than our 304 stainless steel or titanium — but it is not a free-cutting brass. The absence of lead means the chips are continuous, ductile spirals rather than the short, crumbly fragments you get from C36000. On a CNC lathe, chip control is the #1 practical challenge.
Specific behaviors to anticipate:
- Chip wrapping: Long stringy chips can wrap around the tool holder, turret, or workpiece. A chip breaker geometry on the insert is essential; high-pressure coolant directed at the cutting zone helps snap chips.
- Built-up edge (BUE): At low-to-moderate cutting speeds, brass can deposit material on the rake face of the tool, degrading surface finish and dimensional accuracy. A sharp, polished, positive-rake carbide insert largely eliminates BUE once you are above the critical speed threshold for the specific tool-workpiece pair.
- Thermal softening: H62’s thermal conductivity is high (~116 W/(m·K)), so heat dissipates into the chip rather than the workpiece — a net positive for dimensional stability. However, at aggressive parameters the chip itself can become hot enough to degrade the cutting edge if coolant is insufficient.
- Burr formation: H62 is ductile and tends to form burrs at entry/exit edges during milling and drilling. Sharp tools, peck drilling cycles for deep holes, and edge-breaking chamfers programmed into the toolpath all mitigate this.
Starting-Point Machining Parameters
The values below are conditional starting references only. Machine rigidity, spindle power, tool holder balance, coolant pressure, workpiece clamping, and the specific H62 temper (annealed, half-hard, or hard) all shift the practical range. These are not guaranteed recipes and should be verified on a test piece before production.
| Operation | Tool | Speed (m/min) | Feed (mm/rev) | DOC (mm) |
|---|---|---|---|---|
| Turning | Carbide, uncoated polished (K10/K20) | 150 – 250 | 0.08 – 0.30 | 0.5 – 4.0 |
| Milling | Solid carbide end mill, 2–3 flute | 120 – 200 | 0.05 – 0.15 mm/tooth | 0.3 – 2.0 (radial) |
| Drilling | Carbide twist drill, 118° point | 80 – 150 | 0.08 – 0.25 | — |
| Tapping | Spiral-flute HSS tap | 8 – 15 | — | — |
Coolant: Water-soluble semi-synthetic coolant at 5-8% concentration, high-pressure delivery. Flood coolant works for lighter cuts; MQL only for short finishing passes.
Tool coating: Uncoated polished carbide often gives the best surface finish on brass by minimizing friction and BUE. TiN or CrN slightly degrade edge sharpness. TiAlN is reasonable for tool-life priority at higher speeds.
Surface Finishing and Plating
H62 accepts a range of surface treatments without blistering or adhesion failure, which is one reason it dominates decorative and sanitary fitting applications:
- Nickel plating: Provides a hard, corrosion-resistant base layer. Electroless nickel offers uniform thickness on complex geometries. Electrolytic nickel is faster for simple shapes.
- Chromium plating: Applied over a nickel undercoat for decorative bright finishes on faucets, handles, and trim.
- Clear lacquer: Preserves the natural golden brass color while preventing tarnish. Common for architectural hardware.
- Natural patina: Over months to years, H62 darkens to a brownish hue. Some designers specify pre-aged patina for aesthetic effect.
- Polishing and brushing: Mechanical surface finishing to a mirror polish or satin brush is straightforward on H62. Note that a polished surface will show fingerprints and handling marks.
Post-machining cleaning is critical before plating: residual cutting fluid must be removed with an alkaline degrease followed by an acid dip (typically 5-10% sulfuric acid at room temperature) to activate the surface.
Typical Applications
H62 is most commonly specified where the combination of moderate strength, good machinability, excellent cold formability, and low material cost aligns:
- Plumbing and fluid handling: Valve bodies, pipe fittings, water meter housings, pump impellers.
- Electrical: Terminal blocks, switch components, busbar connectors (where conductivity requirements are modest).
- Automotive: Radiator tanks and cores, thermostat housings, sensor bodies.
- Hardware: Locks, hinges, handles, decorative trim, lamp parts.
- Heat exchangers: Tube sheets, baffles, shell-side components in HVAC and industrial heat exchangers.
H62 vs. Common Alternatives
| Property | H62 (CuZn37) | C36000 (CuZn36Pb3) | C26000 (CuZn30) |
|---|---|---|---|
| Copper content | 60.5–63.5% | 60.0–63.0% | 68.5–71.5% |
| Lead content | ≤ 0.08% | 2.5–3.7% | ≤ 0.07% |
| Machinability rating | ~40% (relative to C36000 = 100%) | 100% | ~30% |
| Cold formability | Good | Poor (lead embrittlement) | Excellent |
| Weldability | Good (brazing, resistance welding) | Poor (lead vaporizes) | Good |
| Cost index (relative) | 1.0 | ~1.05–1.15 | ~1.20–1.35 |
| Typical tensile (annealed) | ≥ 290 MPa | ≥ 330 MPa | ≥ 280 MPa |
H62 vs. C36000: C36000 is the go-to free-cutting brass for high-volume CNC turning. It produces short, crumbly chips and extends tool life. However, cold forming (bending, flaring, swaging) on C36000 is severely limited by lead embrittlement, and welding is impractical. Choose H62 when the part will be cold-worked, welded, or brazed after machining.
H62 vs. C26000 (cartridge brass): C26000, with ~30% zinc, is the classic deep-drawing brass for cartridge cases, eyelets, and thin-walled stampings. Its higher copper content makes it more expensive. For general-purpose turned parts that don’t need extreme drawability, H62 is more economical.
Drawing and RFQ Checklist for H62 Parts
When you send an RFQ for CNC-machined H62 components, include the following to receive an accurate quotation:
- Applicable standard: GB/T 5231 (composition), GB/T 4423 (bar/rod), or GB/T 2040 (sheet/strip).
- Material condition: M (annealed), Y2 (half-hard), or Y (hard). This changes machinability, achievable surface finish, and post-machining deformation behavior.
- Complete dimensional drawing: With tolerances per feature, not just a default block tolerance.
- Surface finish requirements: Ra value and measurement standard. As-machined, polished, brushed, or plated.
- Plating specification (if applicable): Type (Ni, Cr, electroless Ni), thickness (per ASTM B733 or equivalent), and any underplate requirement.
- Quantity: Prototype (1-50 pcs), small batch (50-500), or production (500+). The machining strategy and fixturing approach differ significantly between these.
- Inspection requirements: Dimensional inspection plan, material certification (mill test certificate to EN 10204 3.1 or equivalent), and any additional NDT needs.
Submit your drawing, material specification, condition, quantity, tolerances, and surface finish requirements and we will provide a technical evaluation and quotation within one business day.
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