C68800 Brass

Grade Name

Item	Specification
UNS Number	C68800
Common Name	Nickel-Aluminum Brass, High-Strength Brass
Chinese Designation	HAl77-2 (GB/T 5231)
European Standard	CuZn21Al4Ni (DIN 17660)
Primary Standards	ASTM B592, SAE J463, DIN 17672-1

Product Features

Exceptional Corrosion Resistance: Resists dezincification in seawater/chloride environments (salt spray >720 hrs with coating).
High Strength & Wear Resistance: Tensile strength ≥600 MPa (hard temper), hardness ≥260 HB.
Superior Workability: Hot working range 750–870°C; cold elongation ≥35%.
Spark-Resistant: Safe for explosive environments (ISO 80079 compliant).
Thermal Stability: Thermal conductivity 58.6–120 W/m·K; service temp ≤400°C.

Common Product Forms & Dimensions

Form	Thickness/Dia. (mm)	Width/Length (mm)	Special Specifications
Bar	Φ3–200	Cut-to-length: 0.5–6m	Hex/Square/Forged rounds
Plate	0.5–500	Width: 200–2000	Max. single plate: 5 tons
Strip	0.08–2.5	Coil width: 10–600	Slitting tolerance ±0.1mm
Tube	Wall: 0.5–50	OD: 6–530	Seamless/Welded
Wire	Φ0.1–12.0	Coil	Precision grade (±0.01mm)

Note: Custom shapes available (MOQ: 500kg).

Chemical Composition

Element	Standard Range (wt%)	Typical (wt%)	Impurities ≤ (wt%)
Cu	Balance	64.0–67.0	–
Zn	21.3–24.1	Balance	Sn 0.50
Al	3.0–3.8	3.5	Ni 0.50
Co	0.25–0.55	0.4	Si 0.25
Pb	≤0.05	0.03	Fe 0.15
Total Impurities	≤0.3	–	–

*Standard: ASTM B592 (Co/Ni substitution allowed).*

Physical Properties

Property	Value Range	Test Condition
Density (g/cm³)	7.4–8.5	20°C
Melting Point (°C)	900–1000	–
Thermal Conductivity (W/m·K)	58.6–120	20°C
Electrical Conductivity (%IACS)	24–29.5	Annealed
Thermal Expansion (×10⁻⁶/K)	17.6–20.7	20–300°C

Note: Thermal conductivity decreases with higher Al content.

Mechanical Properties

Condition	Tensile Strength (MPa)	Yield Strength (MPa)	Elongation (%)	Hardness
Annealed (O)	294–360	110–140	35–45	70–90 HRB
¼ Hard (H02)	400–460	250–310	18–25	100–125 HV
Hard (H04)	≥490	≥390	≥5	≥150 HV
Hot Rolled	450–550	350–400	10–20	120–150 HV

Data per ASTM E8 (thickness ≤15mm).

Core Advantages

1. Corrosion Resistance Leader: Dezincification rate <0.1 mm/year in seawater.

2. Multi-Process Compatibility: Hot forging yield >95%; cold forming LDR ≥2.0.

3. Intrinsic Safety: Spark-free properties certified to ISO 80079.

4. Cost Efficiency: 20–30% lower cost than stainless steel/bronze alternatives.

Product Applications

Marine Engineering: Seawater valves, propeller shafts, condenser tubes.
Automotive: Fuel injector housings, sensor components (machining tolerance ±0.01mm).
Aerospace: Bearing bushings, hydraulic flanges (high-cycle fatigue resistance).
Electrical: Relay springs, deep-drawn contacts (conductivity ≥24% IACS).
Construction: Corrosion-resistant fasteners for coastal structures.

Processing Guidelines

Process	Key Parameters	Risk Control
Hot Working	750–870°C (finish >550°C)	Control O₂ at 0.5–1.5% to prevent Zn loss
Welding	TIG: 80–120A	Argon purity ≥99.99% + preheat 150°C
Annealing	600–650°C (full)/300°C (stress relief)	N₂ atmosphere anti-oxidation
Surface Treatment	Electroless Ni ≥15μm + Cr 0.3μm	Mandatory for seawater exposure
Machining	Speed: 200–300 m/min	K10 carbide tools + coolant

Key Application Scenarios

Ship Propulsion Systems: 100k DWT vessel seawater pump valves (Ni-Cr coated).
EV Thermal Management: Battery cooling seals (brazing compatible).
Aviation Hydraulics: Landing gear bushings (>500k impact cycles).
Chemical Processing: Acid-resistant agitators in pickling tanks.

FAQs

Q1: Is it RoHS compliant for electronics?

A: Yes (Pb ≤0.05%), but not suitable for potable water systems. Use C26800 instead.

Q2: How to prevent porosity during welding?

A: Increase argon purity to 99.99%, preheat to 150–200°C, post-weld stress relieve at 260°C×1h.

Q3: Corrosion protection for seawater?

A: Electroless Ni (≥15μm) + chromium (0.3μm) coating required. Unprotected dezincification >0.5 mm/year.

Q4: Hot cracking prevention?

A: Limit heating time ≤2h with slightly oxidizing atmosphere (O₂: 0.5–1.5%).

Standard References

Standard System	Code	Scope
US Standard	ASTM B592	Extruded Al-Brass Bars/Shapes
International	SAE J463	Mechanical Properties of Wrought Cu Alloys
European	DIN 17672-1	Tolerances for Forged Cu Alloys
Chinese	GB/T 5231	Wrought Brass Specifications
Japanese	JIS H3250	Cu/Cu-Alloy Rods General Requirements

Technical Note

1. Data based on ASTM standard specimens. Actual properties subject to mill test certificates (MTC).

2. Critical applications require validation testing (e.g., ISO 9227 salt spray, ASME welding qualifications).
Document Version: V2.1
Revision Date: 29 May 2025
Disclaimer: This document does not replace material test reports. FMEA analysis required for high-risk projects.

"C68800 achieves the golden balance of strength and corrosion resistance in marine/aerospace engineering – a benchmark for industrial brass."
— Advanced Copper Alloy Design Handbook, 2024 Edition

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