RFQ Today
Certifications: EN 10204 3.1 / 3.2 material test certificates, dezincification resistance test reports (DZR grades), and complete export documentation packages.
Brass
(CuZn)
A world-class technical reference for EPC contractors, mechanical and piping engineers, procurement heads, and TPI inspection agencies specifying brass (copper-zinc alloy) bar, fittings, and machined components — covering alloy composition and grade selection, the two defining brass-specific failure modes (dezincification and stress corrosion “season cracking”), governing standards, machinability, and the QC and documentation discipline required for EPC and general industrial project supply.
Key Properties
& Grade Selection
Brass — a copper-zinc alloy family — is the default material for the majority of plumbing fittings, valve bodies, hose and pneumatic connectors, and general machined components requiring excellent machinability, good general corrosion resistance, and moderate cost, across a wide range of specific compositions tailored to particular performance and manufacturing requirements.
1.1 — What Brass Is and the Zinc Content Spectrum
Brass is a copper-zinc alloy, with zinc content typically ranging from approximately 5% (gilding metal, primarily used for decorative and coinage applications) up to approximately 40% (Muntz metal and high-zinc structural brasses), with the specific zinc percentage driving the alloy’s mechanical properties, machinability, and corrosion behaviour. Brasses with zinc content up to approximately 35–37% form a single-phase alpha (face-centred cubic) crystal structure, offering excellent ductility and cold-forming characteristics; brasses with higher zinc content (above ~37–39%) develop a two-phase alpha-beta structure, which improves strength and hot-workability but introduces the specific dezincification vulnerability discussed in detail in Section 3.1. For EPC and general engineering fastener, fitting, and machined component applications, the most commercially significant brass grades fall in the 60–70% copper / 30–40% zinc range, discussed by specific grade below.
1.2 — Common Engineering Brass Grades
Free-Cutting Brass (CZ121 / CW614N / C36000)
The workhorse general-engineering brass — approximately 58–61% copper, 35–38% zinc, and 2–3% lead (in the leaded variant), engineered specifically for exceptional machinability. The lead addition forms discrete, soft inclusions that act as internal chip-breakers during machining, dramatically improving tool life and surface finish compared to lead-free brass. The standard material for pneumatic fittings, hose connectors, valve stems, and general machined brass components where high-volume, high-speed CNC machining is the manufacturing route.
Naval Brass (C46400 / CW719R)
Approximately 60% copper, 39.25% zinc, and 0.75% tin — the tin addition significantly improves corrosion resistance in seawater and marine environments compared to standard free-cutting brass, at some cost to machinability. Specified for marine hardware, propeller shafts, and general marine fastener and fitting applications where saltwater exposure is a design consideration.
Admiralty Brass (C44300 / CW706R)
Approximately 71% copper, 28% zinc, 1% tin, with a small arsenic addition (0.02–0.10%) specifically to inhibit dezincification (Section 3.1) — historically the standard material for condenser and heat exchanger tube in marine and power plant applications, now often superseded by more corrosion-resistant alloys (copper-nickel, stainless, titanium) for the most demanding heat exchanger service but still specified in appropriate moderate-severity applications.
Dezincification-Resistant (DZR/CR) Brass (CW602N)
A specifically formulated free-cutting-type brass with controlled, low residual arsenic addition and tightly controlled manufacturing process (including specific annealing treatment) to prevent dezincification even in aggressive water conditions — mandated by many plumbing codes and water utility specifications for potable water fittings and valves in regions with aggressive (soft, chlorinated, or high-temperature) water supply, discussed further in Section 3.1.
1.3 — Key General Properties
| Property | Characteristic |
|---|---|
| Machinability | Excellent (leaded free-cutting grades) — among the best machining ratings of any engineering metal, supporting high-speed, high-volume CNC production |
| Corrosion resistance | Good general atmospheric and freshwater resistance; specific limitations against dezincification and ammonia-induced stress corrosion cracking (Section 3) |
| Thermal/electrical conductivity | Good, though lower than pure copper — brass retains useful thermal/electrical conductivity while offering substantially improved strength and machinability over pure copper |
| Antimicrobial/biostatic properties | Copper-based alloys including brass exhibit natural antimicrobial surface properties, relevant for some hygiene-critical fitting applications |
| Cost | Moderate — generally lower than bronze or nickel alloys, higher than carbon steel, competitive with or below stainless steel depending on market copper/zinc pricing |
Product Forms
& Mechanical Reference
Brass bar, rod, and fitting stock is governed by specific ASTM, EN, and DIN standards, each defining chemical composition, temper, and dimensional requirements. Full detail on related copper-family materials is available in RR Hydraulic’s Copper C110 reference.
Submit grade, form, size, and quantity to sales@rrhydraulics.com for a certified offer.
2.1 — Governing Standards
ASTM B16 — Free-Cutting Brass Rod, Bar, and Shapes
The primary US standard for leaded free-cutting brass bar stock — defines composition (including the lead content range), mechanical properties by temper, and dimensional tolerances for the CZ121/C36000-equivalent material used extensively in machined fitting and component manufacture.
ASTM B121 / B171 — Naval and Admiralty Brass
B121 governs naval brass rod, bar, and shapes; B171 governs admiralty and related brass flat products — the specifications for the marine-grade and dezincification-resistant brass variants discussed in Section 1.2.
EN 12164 / EN 12165
EN 12164 governs copper and copper alloy rod for free machining purposes (the European equivalent to ASTM B16), including the CW602N dezincification-resistant grade; EN 12165 governs wrought and pre-formed copper alloy forging stock — the primary European standards for brass bar and forging stock.
DIN 17660 / DIN 50930-6
DIN 17660 governs wrought copper alloy chemical composition (the German national standard, largely harmonised into EN 12164/12165); DIN 50930-6 specifically addresses dezincification resistance test methodology for copper alloys in contact with drinking water, referenced for DZR/CR brass qualification.
ISO 6957 — Dezincification Resistance Test Method
The international standard test method for evaluating a brass alloy’s resistance to dezincification — immersion in a specified corrosive test solution followed by metallographic examination for dezincification depth, the standard qualification test for DZR/CR brass grades discussed in Section 3.1.
2.2 — Mechanical Properties by Grade and Temper
| Grade | Copper % | Zinc % | Tensile Strength (MPa) | Elongation (%) |
|---|---|---|---|---|
| Free-cutting brass (CZ121/C36000) | 58–61% | 35–38% | 340–420 (as-drawn/machining temper) | 18–30 |
| Naval brass (C46400) | ~60% | ~39.25% (+0.75% Sn) | 380–480 | 25–35 |
| Admiralty brass (C44300) | ~71% | ~28% (+1% Sn, arsenical) | 325–400 | 45–65 |
| DZR brass (CW602N) | ~63% | ~34–35% (+ arsenic) | 360–430 | 18–28 |
Season Cracking
& Design Implications
Brass’s two most distinctive and specification-critical engineering failure modes — dezincification and ammonia-induced stress corrosion cracking (“season cracking”) — are unique to the copper-zinc alloy system and require deliberate design and material selection countermeasures.
3.1 — Dezincification
3.2 — How Dezincification-Resistant (DZR/CR) Brass Prevents the Mechanism
DZR/CR brass grades achieve dezincification resistance primarily through a controlled small addition of arsenic (typically 0.02–0.15%), which inhibits the selective zinc dissolution mechanism, combined with a specific manufacturing process (including a controlled annealing heat treatment step) that produces a particular microstructure less susceptible to the dezincification reaction. This is not simply a matter of composition — the specific combination of controlled arsenic content, correct manufacturing process, and verified performance through standardised testing (ISO 6957 or DIN 50930-6) together define a genuine DZR/CR qualification; a brass alloy with arsenic present but not manufactured and tested to the DZR/CR standard should not be assumed to provide equivalent dezincification resistance without specific verification.
3.3 — Stress Corrosion Cracking (“Season Cracking”)
Stress Relief Annealing as the Primary Countermeasure
Because season cracking requires both sustained tensile stress AND ammonia exposure, removing the residual stress component (through a controlled stress-relief anneal, typically at 250–350°C, well below the temperature that would cause full recrystallisation and loss of the material’s cold-worked strength) after cold forming, machining, or assembly substantially reduces season cracking susceptibility even where some ammonia exposure risk exists.
Avoiding Ammonia-Contact Environments
Where practical, avoiding brass component specification in known ammonia-exposure environments (certain industrial refrigeration systems using ammonia refrigerant, some agricultural and waste-handling environments, and specific cleaning chemical exposure scenarios) is the most direct countermeasure — substituting a non-susceptible material (bronze, stainless steel) where ammonia exposure is a known, unavoidable service condition.
Lower-Zinc Alloys Offer Improved Resistance
Season cracking susceptibility generally increases with zinc content — lower-zinc brasses (closer to the gilding metal end of the composition spectrum) and bronze alloys (copper-tin, with no zinc) offer improved resistance compared to the higher-zinc brasses (35–40% Zn) most commonly used for free-cutting fitting applications, providing an alternative material selection route where season cracking risk is a specific design concern.
Industry Applications
& Documentation
RR Hydraulic maintains full traceability from certified brass billet heat to finished, tested, and packed component shipment. Chemical composition, mechanical, and dezincification resistance verification are standard on all project-grade supply.
4.1 — Inspection & QC Protocol
4.2 — EN 10204 / Documentation Requirements
| Certificate | Content | EPC Requirement | When Mandatory |
|---|---|---|---|
| 2.1 / 2.2 | Declaration / non-specific | Not acceptable for critical potable water/pressure supply | Never for plumbing/pressure-critical brass supply |
| 3.1 (EN 10204) | Heat-traceable chemical + mechanical test report | Mandatory — all EPC supply | All fitting, valve, and general component supply |
| DZR test certificate | ISO 6957 / DIN 50930-6 dezincification test result | Mandatory — potable water / plumbing DZR grade supply | All CW602N/DZR grade fitting and valve supply |
| 3.2 (EN 10204) | 3.1 + TPI countersign | Critical / owner-specified critical items | Safety-critical pressure-boundary components |
4.3 — Applications by Industry
Plumbing and Potable Water Fittings
DZR/CR brass fittings, valve bodies, and connectors for potable water distribution systems where local plumbing codes or water utility specifications mandate dezincification resistance — an increasingly universal requirement across European and many international plumbing standards for water-contact brass components, reflecting the documented, serious consequence of dezincification failure in pressurised water systems.
Pneumatic and Hydraulic Hose Fittings
Free-cutting brass fittings and connectors for compressed air, pneumatic control, and general hydraulic hose connection applications — leveraging the material’s excellent machinability for cost-effective, high-volume CNC production of the varied thread and connection geometries required across this product category.
Marine Hardware
Naval brass fasteners, fittings, and hardware for marine and coastal applications, and admiralty brass for appropriate moderate-severity heat exchanger and condenser tube service — leveraging the tin addition’s specific seawater corrosion resistance improvement over standard free-cutting brass.
4.4 — Export Packaging Specification
- Brass components packed with attention to preventing surface tarnishing during transit — light protective oil or wrap for bright-finish decorative or precision components
- Heat/lot number marked or tagged on each bundle/batch for traceability to the accompanying material test certificate, with clear grade identification (standard vs. DZR/CR) to avoid confusion at site receiving inspection
- Documentation in a waterproof pocket: EN 10204 3.1/3.2 MTC, chemical composition report, mechanical properties report, DZR test certificate (where applicable), and packing list with grade/form/size breakdown per item
- ISPM-15 timber or export cartons for international shipment, with country of origin and HS tariff code documentation matched to the brass product category
Submit your grade, form, size, and quantity to RR Hydraulic for a complete, certified commercial offer.